Powered by Deep Web Technologies
Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Time in quantum mechanics  

E-Print Network [OSTI]

OF CONTENTS I. INTRODUCTION II. HISTORICAL DEVELOPMENT A. Classical Mechanics B. Quantum Theory . C. The Problem 3 4 6 III. TIME ATOMS AND DISCRETE TIME A. The Earliest Applications of Atomistic and Discrete Time . . . . . B. The Radiating Electron... . C. Quantum Field Theory 8 10 l2 IV. TIME OPERATOR FORMULATIONS 16 A. Advocates Against a Time Operator . B. The Possibility of a Time Operator C, Advocates in Favor of a Time Operator D. A Restricted Time Delay Operator: Scattering Theory...

Chapin, Kimberly R.

2012-06-07T23:59:59.000Z

2

Fields and Quantum Mechanics  

E-Print Network [OSTI]

The quantum field theories (QFT) constructed in [1,2] include phenomenology of interest. The constructions approximate: scattering by $1/r$ and Yukawa potentials in non-relativistic approximations; and the first contributing order of the Feynman series for Compton scattering. To have a semi-norm, photon states are constrained to transverse polarizations and for Compton scattering, the constructed cross section deviates at large momentum exchanges from the cross section prediction of the Feynman rules. Discussion includes the incompatibility of canonical quantization with the constructed interacting fields, and the role of interpretations of quantum mechanics in realizing QFT.

Glenn Eric Johnson

2014-12-21T23:59:59.000Z

3

Nonlinear friction in quantum mechanics  

E-Print Network [OSTI]

The effect of nonlinear friction forces in quantum mechanics is studied via dissipative Madelung hydrodynamics. A new thermo-quantum diffusion equation is derived, which is solved for the particular case of quantum Brownian motion with a cubic friction. It is extended also by a chemical reaction term to describe quantum reaction-diffusion systems with nonlinear friction as well.

Roumen Tsekov

2010-03-01T23:59:59.000Z

4

Quo Vadis Quantum Mechanics?  

Science Journals Connector (OSTI)

Quantum mechanics is one of the most successful theoretical structures in all of science. Developed between 1925-26 to explain the optical spectrum of atoms, the theory over the succeeding 80 years has been extended, first to quantum field theories, gauge field theories, and now even string theory. It is used every day by thousands of physicists to calculate physical phenomena to exquisite precision, with no ambiguity in the results. To claim that this is a theory which is not understood by those physicists is absurd. And yet, as eminent a physicist as Richard Feynman, who did as much as anyone else to extend quantum theory to field theories and was a master at producing those exquisite calculations, could say that anyone who claimed they understood quantum theory clearly did not understand quantum theory. One hundred years ago Einstein postulated one of the most unsettling features of the theory, the wave-particle duality, with his particulate explanation for light of the photoelectric effect, and an explanation which was in direct conflict with Maxwell's brilliant development of a wave, or field, theory of light. Einstein believed that the particulate nature would ultimately be explainable by some sort of non-linear theory of electromagnetism, and was outraged by the acceptance of the community of the probabilistic quantum theory. His programme was of course dealt a (near?) fatal blow by Bell's discovery that the three desiderata - a theory which agrees with experiment, a theory which is local in its effects, and a theory in which nature, at its heart, is not probabilistic - are incompatible. That discomfort felt by Einstein and by Feynman is felt by numerous other people as well. This discomfort is heightened by the fact that the theory of gravity, another of Einstein's great achievements, has resisted all efforts at reconciliation with quantum mechanics. This book explores that discomfort, and tries to pin down what the locus of that discomfort is. For many, the locus is in the probabilistic nature at the heart of the theory. Nature should surely, at some fundamental level, know what it is doing. The photon, despite our inability to measure it, should know where it is and how fast it is going. The papers by t'Hooft, Hiley, and Smolin fall into this camp. Some suspect that the macroscopic world of our immediate sense experiences, and the microscopic world of quantum phenomena, are genuinely different, that the fundamental conceptual nature of physics changes from one to the other, with some unknown boundary between them. Penrose, in his preface alludes to his speculations on this, as does Leggett to his own speculations in his paper. And a number of articles (e.g., by Hartle, Rovelli, and others) opine that if only everyone looked at quantum mechanics in the right way (their way), it would lose its mystery, and be as natural as Newton's world view. (I myself tend to this position, which is however somewhat tempered by the realization that the clarity and naturalness of my viewpoint is not shared by the others who believe equally firmly in their own natural, clear, but radically different, viewpoint). A number of articles simply examine the counterintuitive nature of quantum theory in general, using it to make sense of time travel (Greenberger and Svozil) and demonstrating the unusual features of induction about the past from present observations within quantum theory (Aharonov and Dolev). The book is not free from rather overblown titles (e.g., 'Liberation and Purification from Classical Prejudice', or 'A Quantum Theory of the Human Person') but those articles nevertheless contain at least amusing speculations. In quantum gravity, the incompatibilities between the two masterstrokes of the twentieth century are highlighted. There is a strong suspicion amongst many in this field that progress in understanding quantum gravity demands a deeper understanding of the great mystery of quantum theory which this book explores. This book is a useful and, at times, fascinating introduction to the flounderings which are taking pla

W G Unruh

2006-01-01T23:59:59.000Z

5

MiniDFT  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

MiniDFT MiniDFT MiniDFT Description MiniDFT is a plane-wave denstity functional theory (DFT) mini-app for modeling materials. Given an set of atomic coordinates and pseudopotentials, MiniDFT computes self-consistent solutions of the Kohn-Sham equations using either the LDA or PBE exchange-correlation functionals. For each iteration of the self-consistent field cycle, the Fock matrix is constructed and then diagonalized. To build the Fock matrix, Fast Fourier Transforms are used to tranform orbitals from the plane wave basis ( where the kinetic energy is most readily compted ) to real space (where the potential is evaluated ) and back. Davidson diagonalization is used to compute the orbital energies and update the orbital coefficients. The MiniDFT mini-app was excised from the general-purpose Quantum Espresso

6

First principles DFT study of dye-sensitized CdS quantum dots  

SciTech Connect (OSTI)

Dye-sensitized quantum dots (QDs) are considered promising candidates for dye-sensitized solar cells. In order to maximize their efficiency, detailed theoretical studies are important. Here, we report a first principles density functional theory (DFT) investigation of experimentally realized dye - sensitized QD / ligand systems, viz., Cd{sub 16}S{sub 16}, capped with acetate molecules and a coumarin dye. The hybrid B3LYP functional and a 6?311+G(d,p)/LANL2dz basis set are used to study the geometric, energetic and electronic properties of these clusters. There is significant structural rearrangement in all the clusters studied - on the surface for the bare QD, and in the positions of the acetate / dye ligands for the ligated QDs. The density of states (DOS) of the bare QD shows states in the band gap, which disappear on surface passivation with the acetate molecules. Interestingly, in the dye-sensitised QD, the HOMO is found to be localized mainly on the dye molecule, while the LUMO is on the QD, as required for photo-induced electron injection from the dye to the QD.

Jain, Kalpna; Singh, Kh. S. [Department of Physics, D. J. College, Baraut -250611, U.P. (India); Kishor, Shyam, E-mail: shyam387@gmail.com [Department of Chemistry, J. V. College, Baraut -250611, U.P. (India); Josefesson, Ida; Odelius, Michael [Fysikum, Albanova University Center, Stockholm University, S-106 91 Stockholm (Sweden); Ramaniah, Lavanya M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

2014-04-24T23:59:59.000Z

7

Free will and quantum mechanics  

E-Print Network [OSTI]

A simple example is provided showing that violation of free will allows to reproduce the quantum mechanical predictions, and that the Clauser-Horne parameter can take the maximum value 4 for a proper choice.

Antonio Di Lorenzo

2011-05-05T23:59:59.000Z

8

Combined Quantum Mechanical and Molecular Mechanics Studies of...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Mechanical and Molecular Mechanics Studies of the Electron-Transfer Reactions Involving Carbon Tetrachloride in Combined Quantum Mechanical and Molecular Mechanics Studies of the...

9

Effective equations for the quantum pendulum from momentous quantum mechanics  

SciTech Connect (OSTI)

In this work we study the quantum pendulum within the framework of momentous quantum mechanics. This description replaces the Schroedinger equation for the quantum evolution of the system with an infinite set of classical equations for expectation values of configuration variables, and quantum dispersions. We solve numerically the effective equations up to the second order, and describe its evolution.

Hernandez, Hector H.; Chacon-Acosta, Guillermo [Universidad Autonoma de Chihuahua, Facultad de Ingenieria, Nuevo Campus Universitario, Chihuahua 31125 (Mexico); Departamento de Matematicas Aplicadas y Sistemas, Universidad Autonoma Metropolitana-Cuajimalpa, Artificios 40, Mexico D. F. 01120 (Mexico)

2012-08-24T23:59:59.000Z

10

Quantum mechanical effects from deformation theory  

SciTech Connect (OSTI)

We consider deformations of quantum mechanical operators by using the novel construction tool of warped convolutions. The deformation enables us to obtain several quantum mechanical effects where electromagnetic and gravitomagnetic fields play a role. Furthermore, a quantum plane can be defined by using the deformation techniques. This in turn gives an experimentally verifiable effect.

Much, A. [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)] [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig, Germany and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)

2014-02-15T23:59:59.000Z

11

Inertial Force, Equivalence Principle and Quantum Mechanics  

E-Print Network [OSTI]

On the basis of a manifestly covariant formalism of non-relativistic quantum mechanics in general coordinate systems, proposed by us recently, we derive general expressions for inertial forces. The results enable us further to discuss, and to explain the validity of, the equivalence principle in non-relativistic quantum mechanics.

Minoru Omote; Susumu Kamefuchi

2000-05-10T23:59:59.000Z

12

STOPPING TIMES IN QUANTUM MECHANICS  

E-Print Network [OSTI]

(Stinespring, Kraus). 3". Time-dependant case General time evolution of an open quantum sys- tem = (Pt)t0

Attal, Stéphane

13

Operational Axioms for Quantum Mechanics  

E-Print Network [OSTI]

The mathematical formulation of Quantum Mechanics in terms of complex Hilbert space is derived for finite dimensions, starting from a general definition of "physical experiment" and from five simple Postulates concerning "experimental accessibility and simplicity". For the infinite dimensional case, on the other hand, a C*-algebra representation of physical transformations is derived, starting from just four of the five Postulates via a Gelfand-Naimark-Segal (GNS) construction. The present paper simplifies and sharpens the previous derivation in version 1. The main ingredient of the axiomatization is the postulated existence of "faithful states" that allows one to calibrate the experimental apparatus. Such notion is at the basis of the operational definitions of the scalar product and of the "transposed" of a physical transformation. What is new in the present paper with respect to quant-ph/0603011 is the operational deduction of an involution corresponding to the "complex-conjugation" for effects, whose extension to transformations allows to define the "adjoint" of a transformation when the extension is composition-preserving.

Giacomo Mauro D'Ariano

2006-11-08T23:59:59.000Z

14

Topological Strings from Quantum Mechanics  

E-Print Network [OSTI]

We propose a general correspondence which associates a non-perturbative quantum-mechanical operator to a toric Calabi-Yau manifold, and we conjecture an explicit formula for its spectral determinant in terms of an M-theoretic version of the topological string free energy. As a consequence, we derive an exact quantization condition for the operator spectrum, in terms of the vanishing of a generalized theta function. The perturbative part of this quantization condition is given by the Nekrasov-Shatashvili limit of the refined topological string, but there are non-perturbative corrections determined by the conventional topological string. We analyze in detail the cases of local P2, local P1xP1 and local F1. In all these cases, the predictions for the spectrum agree with the existing numerical results. We also show explicitly that our conjectured spectral determinant leads to the correct spectral traces of the corresponding operators, which are closely related to topological string theory at orbifold points. Phys...

Grassi, Alba; Marino, Marcos

2014-01-01T23:59:59.000Z

15

Topological Strings from Quantum Mechanics  

E-Print Network [OSTI]

We propose a general correspondence which associates a non-perturbative quantum-mechanical operator to a toric Calabi-Yau manifold, and we conjecture an explicit formula for its spectral determinant in terms of an M-theoretic version of the topological string free energy. As a consequence, we derive an exact quantization condition for the operator spectrum, in terms of the vanishing of a generalized theta function. The perturbative part of this quantization condition is given by the Nekrasov-Shatashvili limit of the refined topological string, but there are non-perturbative corrections determined by the conventional topological string. We analyze in detail the cases of local P2, local P1xP1 and local F1. In all these cases, the predictions for the spectrum agree with the existing numerical results. We also show explicitly that our conjectured spectral determinant leads to the correct spectral traces of the corresponding operators, which are closely related to topological string theory at orbifold points. Physically, our results provide a Fermi gas picture of topological strings on toric Calabi-Yau manifolds, which is fully non-perturbative and background independent. They also suggest the existence of an underlying theory of M2 branes behind this formulation. Mathematically, our results lead to precise, surprising conjectures relating the spectral theory of functional difference operators to enumerative geometry.

Alba Grassi; Yasuyuki Hatsuda; Marcos Marino

2014-10-13T23:59:59.000Z

16

Fully quantum mechanical description of proteins in solution. Combining linear scaling quantum mechanical methodologies with the Poisson-Boltzmann equation  

SciTech Connect (OSTI)

In this paper the authors report a method for solving the Schroedinger equation for large molecules in solution which involved merging a linear scaling divide and conquer (D and C) semiempirical algorithm with the Poisson-Boltzmann (PB) equation. They then assess the performance of their self-consistent reaction field (SCRF) approach by comparing the D and C-PB calculations for a set of 29 neutral and 36 charged molecules with those obtained by ab initio GVB and DFT (B3LYP) methods, Cramer and Truhlar`s semiempirical generalized-Born SM5 model, and with the experimental solvation free energies. Furthermore, the authors show that their SCRF method can be used to perform fully quantum mechanical calculations of proteins in solution in a reasonable amount of time on a modern workstation. They believe that all electrostatic interactions in biological systems require a quantum mechanical description in order to obtain an accurate representation. Thus, their new SCRF method should have an impact on the computational study of physical and chemical phenomena occurring in proteins and nuclei acids, which are, in general, strongly influenced by electrostatic interactions. Moreover, this may lead to novel insights into classic problems like protein folding or drug design.

Gogonea, V.; Merz, K.M. Jr. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemistry] [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemistry

1999-07-01T23:59:59.000Z

17

From Quantum Mechanics to Quantum Field Theory: The Hopf route  

E-Print Network [OSTI]

From Quantum Mechanics to Quantum Field Theory: The Hopf route A. I. Solomon1 2, G. E. H. Duchamp3. Eliasza-Radzikowskiego 152, PL 31-342 Krak´ow, Poland E-mail: a.i.solomon@open.ac.uk, gduchamp2@free solvable model (at least in the free boson case). On the basis of a combinatorial methodology, we show

Paris-Sud XI, Université de

18

From Quantum Mechanics to Quantum Field Theory: The Hopf route  

E-Print Network [OSTI]

From Quantum Mechanics to Quantum Field Theory: The Hopf route A. I. Solomon 1 2 , G. E. H. Duchamp. Eliasza­Radzikowskiego 152, PL 31­342 Krak??ow, Poland E­mail: a.i.solomon@open.ac.uk, gduchamp2@free solvable model (at least in the free boson case). On the basis of a combinatorial methodology, we show

Recanati, Catherine

19

DFT study on cysteine adsorption mechanism on Au(111) and Au(110)  

SciTech Connect (OSTI)

Periodic density functional theory calculations were used to investigate relevant aspects of adsorption mechanisms of cysteine dimers in protonated form on Au(111) and Au(110) surfaces. The projected densities of states are explicitly discussed for all main chemical groups of cysteine, i.e. the amino group (NH2), the thiol group (SH) and the carboxylic group (COOH) to identify differences in adsorption mechanism. Special emphasis is put on the analysis of changes in the electronic structure of molecules adsorbed on Au(111) and Au(110) surfaces as well as the accompanying charge transfer mechanisms at molecule-substrate interaction.

Buimaga-Iarinca, Luiza; Floare, Calin G.; Calborean, Adrian; Turcu, Ioan [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)

2013-11-13T23:59:59.000Z

20

Quantum Mechanical Search and Harmonic Perturbation  

E-Print Network [OSTI]

Perturbation theory in quantum mechanics studies how quantum systems interact with their environmental perturbations. Harmonic perturbation is a rare special case of time-dependent perturbations in which exact analysis exists. Some important technology advances, such as masers, lasers, nuclear magnetic resonance, etc., originated from it. Here we add quantum computation to this list with a theoretical demonstration. Based on harmonic perturbation, a quantum mechanical algorithm is devised to search the ground state of a given Hamiltonian. The intrinsic complexity of the algorithm is continuous and parametric in both time T and energy E. More precisely, the probability of locating a search target of a Hamiltonian in N-dimensional vector space is shown to be 1/(1+ c N E^{-2} T^{-2}) for some constant c. This result is optimal. As harmonic perturbation provides a different computation mechanism, the algorithm may suggest new directions in realizing quantum computers.

Jie-Hong R. Jiang; Dah-Wei Chiou; Cheng-En Wu

2007-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Scale symmetry in classical and quantum mechanics  

E-Print Network [OSTI]

In this paper we address again the issue of the scale anomaly in quantum mechanical models with inverse square potential. In particular we examine the interplay between the classical and quantum aspects of the system using in both cases an operatorial approach.

E. Gozzi; D. Mauro

2005-07-15T23:59:59.000Z

22

Quantum mechanical stabilization of Minkowski signature wormholes  

SciTech Connect (OSTI)

When one attempts to construct classical wormholes in Minkowski signature Lorentzian spacetimes violations of both the weak energy hypothesis and averaged weak energy hypothesis are encountered. Since the weak energy hypothesis is experimentally known to be violated quantum mechanically, this suggests that a quantum mechanical analysis of Minkowski signature wormholes is in order. In this note I perform a minisuperspace analysis of a simple class of Minkowski signature wormholes. By solving the Wheeler-de Witt equation for pure Einstein gravity on this minisuperspace the quantum mechanical wave function of the wormhole is obtained in closed form. The wormhole is shown to be quantum mechanically stabilized with an average radius of order the Planck length. 8 refs.

Visser, M.

1989-05-19T23:59:59.000Z

23

Nonequilibrium quantum statistical mechanics and thermodynamics  

E-Print Network [OSTI]

The purpose of this work is to discuss recent progress in deriving the fundamental laws of thermodynamics (0th, 1st and 2nd-law) from nonequilibrium quantum statistical mechanics. Basic thermodynamic notions are clarified and different reversible and irreversible thermodynamic processes are studied from the point of view of quantum statistical mechanics. Special emphasis is put on new adiabatic theorems for steady states close to and far from equilibrium, and on investigating cyclic thermodynamic processes using an extension of Floquet theory.

Walid K. Abou Salem

2006-01-23T23:59:59.000Z

24

On the missing axiom of Quantum Mechanics  

E-Print Network [OSTI]

The debate on the nature of quantum probabilities in relation to Quantum Non Locality has elevated Quantum Mechanics to the level of an "Operational Epistemic Theory". In such context the quantum superposition principle has an extraneous non epistemic nature. This leads us to seek purely operational foundations for Quantum Mechanics, from which to derive the current mathematical axiomatization based on Hilbert spaces. In the present work I present a set of axioms of purely operational nature, based on a general definition of "the experiment", the operational/epistemic archetype of information retrieval from reality. As we will see, this starting point logically entails a series of notions [state, conditional state, local state, pure state, faithful state, instrument, propensity (i.e. "effect"), dynamical and informational equivalence, dynamical and informational compatibility, predictability, discriminability, programmability, locality, a-causality, rank of the state, maximally chaotic state, maximally entangled state, informationally complete propensity, etc. ], along with a set of rules (addition, convex combination, partial orderings, ...), which, far from being of quantum origin as often considered, instead constitute the universal "syntactic manual" of the operational/epistemic approach. The missing ingredient is, of course, the quantum superposition axiom for probability amplitudes: for this I propose some substitute candidates of purely operational/epistemic nature.

Giacomo Mauro D'Ariano

2005-06-03T23:59:59.000Z

25

Multichannel framework for singular quantum mechanics  

SciTech Connect (OSTI)

A multichannel S-matrix framework for singular quantum mechanics (SQM) subsumes the renormalization and self-adjoint extension methods and resolves its boundary-condition ambiguities. In addition to the standard channel accessible to a distant (asymptotic) observer, one supplementary channel opens up at each coordinate singularity, where local outgoing and ingoing singularity waves coexist. The channels are linked by a fully unitary S-matrix, which governs all possible scenarios, including cases with an apparent nonunitary behavior as viewed from asymptotic distances. -- Highlights: A multichannel framework is proposed for singular quantum mechanics and analogues. The framework unifies several established approaches for singular potentials. Singular points are treated as new scattering channels. Nonunitary asymptotic behavior is subsumed in a unitary multichannel S-matrix. Conformal quantum mechanics and the inverse quartic potential are highlighted.

Camblong, Horacio E., E-mail: camblong@usfca.edu [Department of Physics and Astronomy, University of San Francisco, San Francisco, CA 94117-1080 (United States); Epele, Luis N., E-mail: epele@fisica.unlp.edu.ar [Laboratorio de Fsica Terica, Departamento de Fsica, IFLP, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 671900 La Plata (Argentina); Fanchiotti, Huner, E-mail: huner@fisica.unlp.edu.ar [Laboratorio de Fsica Terica, Departamento de Fsica, IFLP, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 671900 La Plata (Argentina)] [Laboratorio de Fsica Terica, Departamento de Fsica, IFLP, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 671900 La Plata (Argentina); Garca Canal, Carlos A., E-mail: garcia@fisica.unlp.edu.ar [Laboratorio de Fsica Terica, Departamento de Fsica, IFLP, CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 671900 La Plata (Argentina); Ordez, Carlos R., E-mail: ordonez@uh.edu [Department of Physics, University of Houston, Houston, TX 77204-5506 (United States)

2014-01-15T23:59:59.000Z

26

Electromagnetic angular momentum and quantum mechanics  

Science Journals Connector (OSTI)

A quick way of arriving at the Dirac quantization condition between electric and magnetic charges is to require that the electromagnetic field angular momentum of a Thomson dipole (a magnetic monopole and an electric charge) equal some integer multiple of the fundamental unit of quantum mechanical angular momentum ?/2. Applying this same type of argument to the electromagnetic field angular momentum carried by a magnetic dipoleelectric charge system leads to an infinite number of different quantization conditions and an apparent incompatibility between quantum mechanics and the dipolecharge system. However a more careful analysis shows that the particle plus field angular momentum of this system does satisfy the standard angular momentum commutation relationships and is therefore a good quantum mechanical angular momentum. This emphasizes that caution must be taken when applying such semiclassical quantization arguments. Finally a possible connection between this dipolecharge field angular momentum and the nucleon spin crisis is given.

D. Singleton

1998-01-01T23:59:59.000Z

27

Rovelli' s relational quantum mechanics, monism and quantum becoming  

E-Print Network [OSTI]

In this paper I present and defend Rovelli's relation quantum mechanics from some foreseeable objections, so as to clarify its philosophical implications vis a vis rival interpretations. In particular I ask whether RQM presupposes a hidden recourse to both a duality of evolutions and of ontology (the relationality of quantum world and the intrinsicness of the classical world, which in the limit must be recovered from the former). I then concentrate on the pluralistic, antimonistic metaphysical consequences of the theory, due to the impossibility of assigning a state to the quantum universe. Finally, in the last section I note interesting consequences of RQM with respect to the possibility of defining a local, quantum relativistic becoming (in flat spacetimes).Given the difficulties of having the cosmic form of becoming that would be appropriate for priority monism, RQM seems to present an important advantage with respect to monistic views, at least as far as the possibility of explaining our experience of time is concerned.

Mauro Dorato

2013-08-31T23:59:59.000Z

28

On Time in Quantum Mechanics  

E-Print Network [OSTI]

Although time measurements are routinely performed in laboratories, their theoretical description is still an open problem. Correspondingly, the status of the energy-time uncertainty relation is unsettled. In the first part of this work the necessity of positive operator valued measures (POVM) as descriptions of every quantum experiment is reviewed, as well as the suggestive role played by the probability current in time measurements. Furthermore, it is shown that no POVM exists, which approximately agrees with the probability current on a very natural set of wave functions; nevertheless, the choice of the set is crucial, and on more restrictive sets the probability current does provide a good arrival time prediction. Some ideas to experimentally detect quantum effects in time measurements are discussed. In the second part of the work the energy-time uncertainty relation is considered, in particular for a model of alpha decay for which the variance of the energy can be calculated explicitly, and the variance of time can be estimated. This estimate is tight for systems with long lifetimes, in which case the uncertainty relation is shown to be satisfied. Also the linewidth-lifetime relation is shown to hold, but contrary to the common expectation, it is found that the two relations behave independently, and therefore it is not possible to interpret one as a consequence of the other. To perform the mentioned analysis quantitative scattering estimates are necessary. To this end, bounds of the form $\\|1_Re^{-iHt}\\psi\\|_2^2 \\leq C t^{-3}$ have been derived, where $\\psi$ denotes the initial state, $H$ the Hamiltonian, $R$ a positive constant, and $C$ is explicitly known. As intermediate step, bounds on the derivatives of the $S$-matrix in the form $\\|1_K S^{(n)}\\|_\\infty \\leq C_{n,K} $ have been established, with $n=1,2,3$, and the constants $C_{n,K}$ explicitly known.

Nicola Vona

2014-03-11T23:59:59.000Z

29

Quantum mechanics and the time travel paradox  

E-Print Network [OSTI]

The closed causal chains arising from backward time travel do not lead to paradoxes if they are self consistent. This raises the question as to how physics ensures that only self-consistent loops are possible. We show that, for one particular case at least, the condition of self consistency is ensured by the interference of quantum mechanical amplitudes associated with the loop. If this can be applied to all loops then we have a mechanism by which inconsistent loops eliminate themselves.

David T. Pegg

2005-06-17T23:59:59.000Z

30

WEAK MEASUREMENT IN QUANTUM MECHANICS ABRAHAM NEBEN  

E-Print Network [OSTI]

WEAK MEASUREMENT IN QUANTUM MECHANICS ABRAHAM NEBEN PHYS 342 Final Project March 10, 2011 Contents of Postselection 4 4. Impossible Spin Measurements 5 5. Hardy's Paradox 5 6. Controversy over Weak Measurement 8 7 of a Measurement of a Component of the Spin of a Spin-1/2 Particle Can Turn Out to be 100." [1] The topic

Rosner, Jonathan L.

31

Anomalies in conservation laws in quantum mechanics  

Science Journals Connector (OSTI)

It has been pointed out that a simple quantum-mechanical system, involving a charged particle moving in a uniform magnetic field, can exhibit what looks like an anomaly. This note analyzes the problem, and shows that in such cases the anomaly is (in some sense) already present at the classical level.

R. S. Ward

1987-07-15T23:59:59.000Z

32

Quantum Mechanical Effects in Gravitational Collapse  

E-Print Network [OSTI]

In this thesis we investigate quantum mechanical effects to various aspects of gravitational collapse. These quantum mechanical effects are implemented in the context of the Functional Schr\\"odinger formalism. The Functional Schr\\"odinger formalism allows us to investigate the time-dependent evolutions of the quantum mechanical effects, which is beyond the scope of the usual methods used to investigate the quantum mechanical corrections of gravitational collapse. Utilizing the time-dependent nature of the Functional Schr\\"odinger formalism, we study the quantization of a spherically symmetric domain wall from the view point of an asymptotic and infalling observer, in the absence of radiation. To build a more realistic picture, we then study the time-dependent nature of the induced radiation during the collapse using a semi-classical approach. Using the domain wall and the induced radiation, we then study the time-dependent evolution of the entropy of the domain wall. Finally we make some remarks about the possible inclusion of backreaction into the system.

Eric Greenwood

2010-01-12T23:59:59.000Z

33

Spin Glass: A Bridge between quantum computation and statistical mechanics  

E-Print Network [OSTI]

We show two fascinating topics lying between quantum information processing and statistical mechanics. First, we introduce an elaborated technique, the surface code, to prepare the particular quantum state with robustness against decoherence. Second, we show another interesting technique to employ quantum nature, quantum annealing. Through both of the topics, we would shed light on the birth of the interdisciplinary field between quantum mechanics and statistical mechanics.

Masayuki Ohzeki

2012-04-13T23:59:59.000Z

34

Symmetry and Covariance of Non-relativistic Quantum Mechanics  

E-Print Network [OSTI]

On the basis of a 5-dimensional form of space-time transformations non-relativistic quantum mechanics is reformulated in a manifestly covariant manner. The resulting covariance resembles that of the conventional relativistic quantum mechanics.

Minoru Omote; Susumu Kamefuchi

2000-05-10T23:59:59.000Z

35

1/N expansion in noncommutative quantum mechanics  

SciTech Connect (OSTI)

We study the 1/N expansion in noncommutative quantum mechanics for the anharmonic and Coulombian potentials. The expansion for the anharmonic oscillator presented good convergence properties, but for the Coulombian potential, we found a divergent large N expansion when using the usual noncommutative generalization of the potential. We proposed a modified version of the noncommutative Coulombian potential which provides a well-behaved 1/N expansion.

Ferrari, A. F. [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas, Rua Santa Adelia, 166, 09210-170, Santo Andre, SP (Brazil); Gomes, M.; Stechhahn, C. A. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo - SP (Brazil)

2010-08-15T23:59:59.000Z

36

Hybrid Quantum Mechanical/Molecular Mechanics Study of the SN2 Reaction of CH3Cl+OH? in Water  

SciTech Connect (OSTI)

The SN2 mechanism for the reaction of CH3Cl + OH? in aqueous solution was investigated using combined quantum mechanical and molecular mechanics methodology. We analyzed structures of reactant, transition and product states along the reaction pathway. The free energy profile was calculated using the multi-layered representation with the DFT and CCSD(T) level of theory for the quantum-mechanical description of the reactive region. Our results show that the aqueous environment has a significant impact on the reaction process. We find that solvation energy contribution raises the reaction barrier by ~18.9 kcal/mol and the reaction free energy by ~24.5 kcal/mol. The presence of the solvent also induces perturbations in the electronic structure of the solute leading to an increase of 3.5 kcal/mol for the reaction barrier and a decrease of 5.6 kcal/mol for the reaction free energy respectively. Combining the results of two previous calculation results on CHCl3 + OH? and CH2Cl2 + OH? reactions in water, we demonstrate that increase in the chlorination of the methyl group (from CH3Cl to CHCl3) is accompanied by the decrease in the free energy reaction barrier, with the CH3Cl + OH? having the largest barrier among the three reactions.

Yin, Hongyun; Wang, Dunyou; Valiev, Marat

2011-11-03T23:59:59.000Z

37

Quantum Entanglement and Decoherence: Beyond Particle Models. A Farewell to Quantum Mechanics's Weirdness  

E-Print Network [OSTI]

Combining abstract to laboratory projected quantum states a general analysis of headline quantum phenomena is presented. Standard representation mode is replaced; instead quantum states sustained by elementary material constituents occupy its place. Renouncing to assign leading roles to language originated in classical physics when describing genuine quantum processes, together with sustainment concept most, if not all weirdness associated to Quantum Mechanics vanishes.

O. Tapia

2014-04-02T23:59:59.000Z

38

Neutrino oscillations: Quantum mechanics vs. quantum field theory  

SciTech Connect (OSTI)

A consistent description of neutrino oscillations requires either the quantum-mechanical (QM) wave packet approach or a quantum field theoretic (QFT) treatment. We compare these two approaches to neutrino oscillations and discuss the correspondence between them. In particular, we derive expressions for the QM neutrino wave packets from QFT and relate the free parameters of the QM framework, in particular the effective momentum uncertainty of the neutrino state, to the more fundamental parameters of the QFT approach. We include in our discussion the possibilities that some of the neutrino's interaction partners are not detected, that the neutrino is produced in the decay of an unstable parent particle, and that the overlap of the wave packets of the particles involved in the neutrino production (or detection) process is not maximal. Finally, we demonstrate how the properly normalized oscillation probabilities can be obtained in the QFT framework without an ad hoc normalization procedure employed in the QM approach.

Akhmedov, Evgeny Kh.; Kopp, Joachim; ,

2010-01-01T23:59:59.000Z

39

To Principles of Quantum Mechanics Development  

E-Print Network [OSTI]

New insight to the principles of the quantum physics development is given. The correct ways for the construction of new versions of quantum mechanics on the second main postulate base are discussed. The conclusion on the status of the second main postulate is given. Its formulation in all textbooks has to be represented in the form of statement, since the hypothesis of Schr\\"odinger on the existance of the field scalar function, being to be observable quantity, just charge density, is strictly proved for the case of EM-field, the role of which is argued to be decisive for the dynamics of the atomic systems. It is shown, that the field scalar function, being to be the function the only of coordinates and time, actually describes the state of the system. The second main postulate in Schr\\"odinger formulation is mathematically strictly grounded, but in the popular probabilistic form used in modern textbooks on quantum theory it cannot be proved. The probabilistic theatise, proposed by Born is true in a number of special cases, quite correctly indicated by Dirac. The possible ways of the development of quantum theory, based on clear understanding of the origin of corpuscular-wave dualism are analysed.

Dmitri Yerchuck; Alla Dovlatova; Felix Borovik; Yauhen Yerchak; Vyacheslav Stelmakh

2014-07-09T23:59:59.000Z

40

Quantum mechanics with coordinate dependent noncommutativity  

SciTech Connect (OSTI)

Noncommutative quantum mechanics can be considered as a first step in the construction of quantum field theory on noncommutative spaces of generic form, when the commutator between coordinates is a function of these coordinates. In this paper we discuss the mathematical framework of such a theory. The noncommutativity is treated as an external antisymmetric field satisfying the Jacobi identity. First, we propose a symplectic realization of a given Poisson manifold and construct the Darboux coordinates on the obtained symplectic manifold. Then we define the star product on a Poisson manifold and obtain the expression for the trace functional. The above ingredients are used to formulate a nonrelativistic quantum mechanics on noncommutative spaces of general form. All considered constructions are obtained as a formal series in the parameter of noncommutativity. In particular, the complete algebra of commutation relations between coordinates and conjugated momenta is a deformation of the standard Heisenberg algebra. As examples we consider a free particle and an isotropic harmonic oscillator on the rotational invariant noncommutative space.

Kupriyanov, V. G. [CMCC, Universidade Federal do ABC, Santo Andr, SP (Brazil)] [CMCC, Universidade Federal do ABC, Santo Andr, SP (Brazil)

2013-11-15T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Adenosine Triphosphate Hydrolysis Mechanism in Kinesin Studied by Combined Quantum-Mechanical/Molecular-Mechanical Metadynamics Simulations  

Science Journals Connector (OSTI)

Adenosine Triphosphate Hydrolysis Mechanism in Kinesin Studied by Combined Quantum-Mechanical/Molecular-Mechanical Metadynamics Simulations ... Future extensive molecular mechanical MD simulations exploring the stability of the various states would be very beneficial, although they are outside the scope of the present work. ... Here, we discuss the functions and mechanisms of action of three such crosslinkers: the motors kinesin-5 and kinesin-14, and the non-motor MAPs of the Ase1p family. ...

Matthew J. McGrath; I.-F. Will Kuo; Shigehiko Hayashi; Shoji Takada

2013-05-23T23:59:59.000Z

42

5.74 Introductory Quantum Mechanics II, Spring 2005  

E-Print Network [OSTI]

Time-dependent quantum mechanics and spectroscopy. Topics covered include perturbation theory, two-level systems, light-matter interactions, relaxation in quantum systems, correlation functions and linear response theory, ...

Tokmakoff, Andrei

43

A Global Optimization Approach to Quantum Mechanics  

E-Print Network [OSTI]

This paper presents a global optimization approach to quantum mechanics, which describes the most fundamental dynamics of the universe. It suggests that the wave-like behavior of (sub)atomic particles could be the critical characteristic of a global optimization method deployed by nature so that (sub)atomic systems can find their ground states corresponding to the global minimum of some energy function associated with the system. The classic time-independent Schrodinger equation is shown to be derivable from the global optimization method to support this argument.

Xiaofei Huang

2006-05-25T23:59:59.000Z

44

Quantum Mechanics associated with a Finite Group  

E-Print Network [OSTI]

I describe, in the simplified context of finite groups and their representations, a mathematical model for a physical system that contains both its quantum and classical aspects. The physically observable system is associated with the space containing elements fxf for f an element in the regular representation of a given finite group G. The Hermitian portion of fxf is the Wigner distribution of f whose convolution with a test function leads to a mathematical description of the quantum measurement process. Starting with the Jacobi group that is formed from the semidirect product of the Heisenberg group with its automorphism group SL(2,F{N}) for N an odd prime number I show that the classical phase space is the first order term in a series of subspaces of the Hermitian portion of fxf that are stable under SL(2,F{N}). I define a derivative that is analogous to a pseudodifferential operator to enable a treatment that parallels the continuum case. I give a new derivation of the Schrodinger-Weil representation of the Jacobi group. Keywords: quantum mechanics, finite group, metaplectic. PACS: 03.65.Fd; 02.10.De; 03.65.Ta.

Robert W. Johnson

2006-04-20T23:59:59.000Z

45

To Principles of Quantum Mechanics Development  

E-Print Network [OSTI]

New insight to the principles of the quantum physics development is given. The correct ways for the construction of new versions of quantum mechanics on the second main postulate base are discussed. The conclusion on the status of the second main postulate is given. Its formulation in all textbooks has to be represented in the form of statement, since the hypothesis of Schr\\"odinger on the existance of the field scalar function, being to be observable quantity, just charge density, is strictly proved for the case of EM-field, the role of which is argued to be decisive for the dynamics of the atomic systems. It is shown, that the field scalar function, being to be the function the only of coordinates and time, actually describes the state of the system. The second main postulate in Schr\\"odinger formulation is mathematically strictly grounded, but in the popular probabilistic form used in modern textbooks on quantum theory it cannot be proved. The probabilistic theatise, proposed by Born is true in a number of...

Yerchuck, Dmitri; Borovik, Felix; Yerchak, Yauhen; Stelmakh, Vyacheslav; Dodin, Ilya

2014-01-01T23:59:59.000Z

46

A Foundation Theory of Quantum Mechanics  

E-Print Network [OSTI]

The nRules are empirical regularities that were discovered in macroscopic situations where the outcome is known. When they are projected theoretically into the microscopic domain they predict a novel ontology including the frequent collapse of an atomic wave function, thereby defining an nRule based foundation theory. Future experiments can potentially discriminate between this and other foundation theories of (non-relativistic) quantum mechanics. Important features of the nRules are: (1) they introduce probability through probability current rather than the Born rule, (2) they are valid independent of size (micro or macroscopic), (3) they apply to individual trials, not just to ensembles of trials. (4) they allow all observers to be continuously included in the system without ambiguity, (5) they account for the collapse of the wave function without introducing new or using old physical constants, and (6) in dense environments they provide a high frequency of stochastic localizations of quantum mechanical objects. Key words: measurement, stochastic choice, state reduction.

Richard A Mould

2006-07-10T23:59:59.000Z

47

Fundamental phenomena of quantum mechanics explored with neutron interferometers  

E-Print Network [OSTI]

Ongoing fascination with quantum mechanics keeps driving the development of the wide field of quantum-optics, including its neutron-optics branch. Application of neutron-optical methods and, especially, neutron interferometry and polarimetry has a long-standing tradition for experimental investigations of fundamental quantum phenomena. We give an overview of related experimental efforts made in recent years.

J. Klepp; S. Sponar; Y. Hasegawa

2014-07-09T23:59:59.000Z

48

On some hydrodynamical aspects of quantum mechanics  

E-Print Network [OSTI]

In this note we first set up an analogy between spin and vorticity of a perfect 2d-fluid flow, based on the Borel-Weil contruction of the irreducible unitary representations of SU(2), and looking at the Madelung-Bohm velocity attached to the ensuing spin wave functions. We also show that, in the framework of finite dimensional geometric quantum mechanics, the Schr\\"odinger velocity field on projective Hilbert space is divergence-free (being Killing with respect to the Fubini-Study metric) and fulfils the stationary Euler equation, with pressure proportional to the Hamiltonian uncertainty (squared). We explicitly compute the pressure gradient of this "Schr\\"odinger fluid" and determine its critical points. Its vorticity is also calculated and shown to depend on the spacings of the energy levels. These results follow from hydrodynamical properties of Killing vector fields valid in any (finite dimensional) Riemannian manifold, of possible independent interest.

Mauro Spera

2009-02-04T23:59:59.000Z

49

Is Quantum Mechanics the Whole Truth?  

SciTech Connect (OSTI)

Quantum mechanics has been enormously successful in describing nature at the atomic level and most physicists believe it is, in principle, the 'whole truth' about the world even at the everyday level. However, such a view, at first glance, leads to a severe problem. In certain circumstances, the most natural interpretation of the theory implies that no definite outcome of an experiment occurs until the act of observation. For many decades this problem was regarded as merely philosophical-it was thought it had no consequences that could be tested in experiment. However, in the last dozen years or so, the situation has changed dramatically in this respect. The problem, some popular resolutions of it, the current experimental situation and prospects for the future are discussed.

Leggett, Anthony J. [University of Illinois at Urbana-Champaign (United States)

2008-05-29T23:59:59.000Z

50

Twist deformation of rotationally invariant quantum mechanics  

SciTech Connect (OSTI)

Noncommutative quantum mechanics in 3D is investigated in the framework of an abelian Drinfeld twist which deforms a given Hopf algebra structure. Composite operators (of coordinates and momenta) entering the Hamiltonian have to be reinterpreted as primitive elements of a dynamical Lie algebra which could be either finite (for the harmonic oscillator) or infinite (in the general case). The deformed brackets of the deformed angular momenta close the so(3) algebra. On the other hand, undeformed rotationally invariant operators can become, under deformation, anomalous (the anomaly vanishes when the deformation parameter goes to zero). The deformed operators, Taylor-expanded in the deformation parameter, can be selected to minimize the anomaly. We present the deformations (and their anomalies) of undeformed rotationally invariant operators corresponding to the harmonic oscillator (quadratic potential), the anharmonic oscillator (quartic potential), and the Coulomb potential.

Chakraborty, B. [S.N. Bose National Center for Basic Sciences, JD Block, Sector III, Salt-Lake, Kolkata-700098 (India); Kuznetsova, Z. [UFABC, Rua Catequese 242, Bairro Jardim, cep 09090-400, Santo Andre (Brazil); Toppan, F. [CBPF, Rua Dr. Xavier Sigaud 150, cep 22290-180, Rio de Janeiro (Brazil)

2010-11-15T23:59:59.000Z

51

New methods for quantum mechanical reaction dynamics  

SciTech Connect (OSTI)

Quantum mechanical methods are developed to describe the dynamics of bimolecular chemical reactions. We focus on developing approaches for directly calculating the desired quantity of interest. Methods for the calculation of single matrix elements of the scattering matrix (S-matrix) and initial state-selected reaction probabilities are presented. This is accomplished by the use of absorbing boundary conditions (ABC) to obtain a localized (L{sup 2}) representation of the outgoing wave scattering Green`s function. This approach enables the efficient calculation of only a single column of the S-matrix with a proportionate savings in effort over the calculation of the entire S-matrix. Applying this method to the calculation of the initial (or final) state-selected reaction probability, a more averaged quantity, requires even less effort than the state-to-state S-matrix elements. It is shown how the same representation of the Green`s function can be effectively applied to the calculation of negative ion photodetachment intensities. Photodetachment spectroscopy of the anion ABC{sup -} can be a very useful method for obtaining detailed information about the neutral ABC potential energy surface, particularly if the ABC{sup -} geometry is similar to the transition state of the neutral ABC. Total and arrangement-selected photodetachment spectra are calculated for the H{sub 3}O{sup -} system, providing information about the potential energy surface for the OH + H{sub 2} reaction when compared with experimental results. Finally, we present methods for the direct calculation of the thermal rate constant from the flux-position and flux-flux correlation functions. The spirit of transition state theory is invoked by concentrating on the short time dynamics in the area around the transition state that determine reactivity. These methods are made efficient by evaluating the required quantum mechanical trace in the basis of eigenstates of the Boltzmannized flux operator.

Thompson, W.H. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States)

1996-12-01T23:59:59.000Z

52

Quantum Mechanics Summary/Review Spring 2009 Compton Lecture Series  

E-Print Network [OSTI]

Quantum Mechanics Summary/Review Spring 2009 Compton Lecture Series: From Quantum Mechanics is a constant of nature known as "Planck's constant." ­ The larger is, the more like a wave the object behaves a magnetic field around the particle and interacts with external magnetic fields. (This is the cause

53

Green's Functions and Their Applications to Quantum Mechanics  

E-Print Network [OSTI]

Green's Functions and Their Applications to Quantum Mechanics Jeff Schueler June 2, 2011 Contents 1 Green's Functions in Quantum Mechanics and Many-body Theory 8 3.1 Time Independent Green's Fuctions . . . . . . . . . . . . . . 8 3.2 Solving the Schr¨odinger Equation Using Green's Functions . . 12 4 Conclusion 13 1 #12

Morrow, James A.

54

Evolution of Schrodinger Uncertainty Relation in Quantum Mechanics  

E-Print Network [OSTI]

In the present article, we discuss one of the basic relations of Quantum Mechanics - the Uncertainty Relation (UR). In 1930, few years after Heisenberg, Erwin Schrodinger generalized the famous Uncertainty Relation in Quantum Mechanics, making it more precise than the original. The present study discusses recent generalizations of Schrodinger's work and explains why his paper remains almost forgotten in the last century.

A Angelow

2008-06-07T23:59:59.000Z

55

Lattice Boltzmann equation for relativistic quantum mechanics  

Science Journals Connector (OSTI)

...V. Coveney and S. Succi Lattice Boltzmann equation for relativistic quantum...Relativistic versions of the quantum lattice Boltzmann equation are discussed. It...by a multicomponent complex lattice Boltzmann equation. Lattice Boltzmann...

2002-01-01T23:59:59.000Z

56

Highlighting the mechanism of the quantum speedup by time-symmetric and relational quantum mechanics  

E-Print Network [OSTI]

Bob hides a ball in one of four drawers. Alice is to locate it. Classically she has to open up to three drawers, quantally just one. The fundamental reason for this quantum speedup is not known. We explain it by extending the usual representation of the quantum algorithm, limited to the process of solving the problem, to the process of setting the problem. The number of the drawer with the ball becomes a unitary transformation of the random outcome of the preparation measurement. This brings in relational quantum mechanics: the extension is with respect to Bob and cannot be with respect to Alice. It would tell her the drawer number before she opens any drawer. To Alice, the projection of the quantum state due to the preparation measurement should be retarded at the end of her search; in the input state of the search, the drawer number is determined to Bob and undetermined to Alice. A second consequence is the emergence of an ambiguity. Either the preparation measurement or the final one required to read the solution selects the solution. For reasons of symmetry, we assume that the selection shares evenly between the two measurements. All is as if Alice, by reading the solution, selected half of the information that specifies the drawer number. This selection leaves the input state to Bob unaltered and projects that to Alice on a state of lower entropy where she knows that half in advance. The quantum algorithm is a sum over histories in each of which Alice knows in advance that the ball is in a pair of drawers and locates it by opening one of the two. More in general, given an oracle problem, this explanation of the speedup predicts the number of queries required to solve it in an optimal quantum way.

Giuseppe Castagnoli

2014-12-11T23:59:59.000Z

57

Potentiality and Contradiction in Quantum Mechanics  

E-Print Network [OSTI]

Following J.-Y.B\\'eziau in his pioneer work on non-standard interpretations of the traditional square of opposition, we have applied the abstract structure of the square to study the relation of opposition between states in superposition in orthodox quantum mechanics in \\cite{are14}. Our conclusion was that such states are \\ita{contraries} (\\ita{i.e.} both can be false, but both cannot be true), contradicting previous analyzes that have led to different results, such as those claiming that those states represent \\ita{contradictory} properties (\\ita{i. e.} they must have opposite truth values). In this chapter we bring the issue once again into the center of the stage, but now discussing the metaphysical presuppositions which underlie each kind of analysis and which lead to each kind of result, discussing in particular the idea that superpositions represent potential contradictions. We shall argue that the analysis according to which states in superposition are contrary rather than contradictory is still more plausible.

Jonas R. B. Arenhart; Dcio Krause

2014-06-07T23:59:59.000Z

58

Mechanism of Selective Oxidation of Propene to Acrolein on Bismuth Molybdates from Quantum Mechanical Calculations  

E-Print Network [OSTI]

Mechanism of Selective Oxidation of Propene to Acrolein on Bismuth Molybdates from Quantum for understanding the fundamental chemical mechanisms underlying the selective oxidation of propene to acrolein to form acrolein, and acrolein desorption. The formation of -allyl intermediate is reversible

Goddard III, William A.

59

A small Handbook of Quantum Mechanics A. Nony Mous  

E-Print Network [OSTI]

A small Handbook of Quantum Mechanics A. Nony Mous "Seek simplicity and distrust it.". . . Alfred Spaces And All That 1.1 Introduction This handbook is meant to be a short introduction to Quantum of the mathematical formalism in a conceptual way. Among the major "discoveries" of physics in the twentieth century

Hart, Gus

60

Quantum Mechanics, Group Theory, and C60 Frank Rioux  

E-Print Network [OSTI]

production in macroscopic amounts2 has generated a tremendous amount of research activity in chemistry and the angular momentum quantum number. (1) Just as the quantum mechanical solution for the one-electron hydrogen all other levels are completely filled. Using traditional group theoretical methods6 , it can be shown that

Rioux, Frank

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

24.111 Philosophy of Quantum Mechanics, Spring 2002  

E-Print Network [OSTI]

Quantum mechanics is said to describe a world in which physical objects often lack "definite" properties, indeterminism creeps in at the point of "observation," ordinary logic does not apply, and distant events are perfectly ...

Hall, Edward J. (Edward Jonathon), 1966-

62

Quantum mechanics helps in learning for more intelligent robot  

E-Print Network [OSTI]

A learning algorithm based on state superposition principle is presented. The physical implementation analysis and simulated experiment results show that quantum mechanics can give helps in learning for more intelligent robot.

Dao-Yi Dong; Chun-Lin Chen; Zong-Hai Chen; Chen-Bin Zhang

2005-06-18T23:59:59.000Z

63

EPR, Bell, GHZ, and Hardy theorems, and quantum mechanics  

E-Print Network [OSTI]

We review the theorems of Einstein-Podolsky-Rosen (EPR), Bell, Greenberger-Horne-Zeilinger (GHZ), and Hardy, and present arguments supporting the idea that quantum mechanics is a complete, causal, non local, and non separable theory.

Miguel Socolovsky

2005-08-09T23:59:59.000Z

64

Nonlinear Phenomenology from Quantum Mechanics: Soliton in a Lattice  

E-Print Network [OSTI]

We study a soliton in an optical lattice holding bosonic atoms quantum mechanically using both an exact numerical solution and quantum Monte Carlo simulations. The computation of the state is combined with an explicit account of the measurements of the numbers of the atoms at the lattice sites. In particular, importance sampling in the quantum Monte Carlo method arguably produces faithful simulations of individual experiments. Even though the quantum state is invariant under lattice translations, an experiment may show a noisy version of the localized classical soliton.

Juha Javanainen; Uttam Shrestha

2009-03-29T23:59:59.000Z

65

Electron exchange-correlation in quantum mechanics  

SciTech Connect (OSTI)

It is shown that Fermi-Dirac statistics is guaranteed by the Dirac current, from which spin-dependent quantum velocity fields and spin-dependent quantum trajectories can be inferred. Pauli's exclusion principle is demonstrated using the spin-dependent quantum trajectories. The Dirac current, unlike the Schroedinger current, is nonzero for stationary bound states due to the permanent magnetic moment of the electron. It is of order c{sup 0} in agreement with observation that Fermi-Dirac statistics is independent of electronic velocity. In summary the physical basis for exchange-correlation is found in Dirac's equation, although Schroedinger's equation may be used to evaluate the Dirac current in the nonrelativistic regime of electronic velocity.

Ritchie, B

2009-01-30T23:59:59.000Z

66

Comment on 'Nonlocality, Counterfactuals and Quantum Mechanics'  

SciTech Connect (OSTI)

A recent proof [H. P. Stapp, Am. J. Phys. 65, 300 (1997)], formulated in the symbolic language of modal logic, claims to show that contemporary quantum theory, viewed as a set of rules that allow us to calculate statistical predictions among certain kinds of observations, cannot be imbedded in any rational framework that conforms to the principles that (1) the experimenters' choices of which experiments they will perform can be considered to be free choices, (2) outcomes of measurements are unique, and (3) the free choices just mentioned have no backward-in-time effects of any kind. This claim is similar to Bell's theorem, but much stronger, because no reality assumption alien to quantum philosophy is used. The paper being commented on [W. Unruh, Phys. Rev. A 59, 126 (1999)] argues that some such reality assumption has been ''smuggled'' in. That argument is examined here and shown, I believe, to be defective.

Stapp, H.P.

1999-04-14T23:59:59.000Z

67

Transition From Quantum To Classical Mechanics As Information Localization  

E-Print Network [OSTI]

Quantum parallelism implies a spread of information over the space in contradistinction to the classical mechanical situation where the information is "centered" on a fixed trajectory of a classical particle. This means that a quantum state becomes specified by more indefinite data. The above spread resembles, without being an exact analogy, a transfer of energy to smaller and smaller scales observed in the hydrodynamical turbulence. There, in spite of the presence of dissipation (in a form of kinematic viscosity), energy is still conserved. The analogy with the information spread in classical to quantum transition means that in this process the information is also conserved. To illustrate that, we show (using as an example a specific case of a coherent quantum oscillator) how the Shannon information density continuously changes in the above transition . In a more general scheme of things, such an analogy allows us to introduce a "dissipative" term (connected with the information spread) in the Hamilton-Jacobi equation and arrive in an elementary fashion at the equations of classical quantum mechanics (ranging from the Schr\\"{o}dinger to Klein-Gordon equations). We also show that the principle of least action in quantum mechanics is actually the requirement for the energy to be bounded from below.

A. Granik

2005-03-18T23:59:59.000Z

68

Large Scale Quantum-mechanical Calculations of Proteins, Nanomaterials and  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Large Scale Quantum-mechanical Calculations of Proteins, Nanomaterials and Large Scale Quantum-mechanical Calculations of Proteins, Nanomaterials and Other Large Systems Event Sponsor: Leadership Computing Facility Seminar Start Date: Dec 5 2013 - 2:00pm Building/Room: Building 240/Room 4301 Location: Argonne National Laboratory Speaker(s): Dmitri G. Fedorov Speaker(s) Title: National Institute of Advanced Industrial Science and Technology (AIST) Host: Yuri Alexeev Our approach to large scale calculations is based on fragmenting a molecular system into pieces, and performing quantum-mechanical calculations of these fragments and their pairs in the fragment molecular orbital method (FMO). After a brief summary of the methodology, some typical applications to protein-ligand complexes, chemical reactions in explicit solvent, and nanomaterials (silicon nanowires, zeolites.

69

Quantum-mechanical description of in-medium fragmentation  

E-Print Network [OSTI]

We present a quantum-mechanical description of quark-hadron fragmentation in a nuclear environment. It employs the path-integral formulation of quantum mechanics, which takes care of all phases and interferences, and which contains all relevant time scales, like production, coherence, formation, etc. The cross section includes the probability of pre-hadron (colorless dipole) production both inside and outside the medium. Moreover, it also includes inside-outside production, which is a typical quantum-mechanical interference effect (like twin-slit electron propagation). We observe a substantial suppression caused by the medium, even if the pre-hadron is produced outside the medium and no energy loss is involved. This important source of suppression is missed in the usual energy-loss scenario interpreting the effect of jet quenching observed in heavy ion collisions. This may be one of the reasons of a too large gluon density, reported by such analyzes.

B. Z. Kopeliovich; H. -J. Pirner; I. K. Potashnikova; Ivan Schmidt; A. V. Tarasov; O. O. Voskresenskaya

2008-09-27T23:59:59.000Z

70

A New Look at the Quantum Mechanical Problem of Measurement  

Science Journals Connector (OSTI)

According to orthodox quantum mechanics state vectors change in two incompatible ways: deterministically in accordance with Schr0?dinger's time-dependent equation and probabilistically if and only if a measurement is made. It is argued here that the problem of measurement arises because the precise mutually exclusive conditions for these two types of transitions to occur are not specified within orthodox quantum mechanics. Fundamentally this is due to an inevitable ambiguity in the notion of measurement itself. Hence if the problem of measurement is to be resolved a new fully objective version of quantum mechanics needs to be developed which does not incorporate the notion of measurement in its basic postulates at all.

Nicholas Maxwell

1972-01-01T23:59:59.000Z

71

About the notion of truth in quantum mechanics  

SciTech Connect (OSTI)

The meaning of truth in quantum mechanics is considered in order to respond to some objections raised by B. d'Espagnat against a logical interpretation of quantum mechanics recently proposed by the author. A complete answer is given. It is shown that not only can factual data be said to be true, but also some of their logical consequences, so that the definition of truth given by Heisenberg is both extended and refined. Some nontrue but reliable propositions may also be used, but they are somewhat arbitrary because of the complementarity principle. For instance, the propositions expressing wave packet reduction can be either true or reliable, according to the case under study. Separability is also discussed: as far as the true properties of an individual system are concerned, quantum mechanics is separable.

Omnes, R. (Univ. de Paris-Sud, Orsay (France))

1991-02-01T23:59:59.000Z

72

Quantum Mechanics and Discrete Time from "Timeless" Classical Dynamics  

E-Print Network [OSTI]

We study classical Hamiltonian systems in which the intrinsic proper time evolution parameter is related through a probability distribution to the physical time, which is assumed to be discrete. - This is motivated by the ``timeless'' reparametrization invariant model of a relativistic particle with two compactified extradimensions. In this example, discrete physical time is constructed based on quasi-local observables. - Generally, employing the path-integral formulation of classical mechanics developed by Gozzi et al., we show that these deterministic classical systems can be naturally described as unitary quantum mechanical models. The emergent quantum Hamiltonian is derived from the underlying classical one. It is closely related to the Liouville operator. We demonstrate in several examples the necessity of regularization, in order to arrive at quantum models with bounded spectrum and stable groundstate.

H. -T. Elze

2003-07-03T23:59:59.000Z

73

Can the photosynthesis first step quantum mechanism be explained?  

E-Print Network [OSTI]

Photosynthesis first step mechanism concerns the sunlight absorption and both negative and positive charges separation. Recent and important photosynthesis literature claims that this mechanism is quantum mechanics controlled, however without presenting qualitative or quantitative scientifically based mechanism. The present accepted and old-fashioned photosynthesis mechanism model suffers from few drawbacks and an important issue is the absence of driving force for negative and positive charges separation. This article presents a new qualitative model for this first step mechanism in natural catalytic systems such as photosynthesis in green leaves. The model uses a concept of semiconductor band gap engineering, such as the staggered energy band gap line-up in semiconductors. To explain the primary mechanism in natural photosynthesis the proposal is the following: incident light is absorbed inside the leaves causing charges separation. The only energetic configuration that allows charges separation under illum...

Sacilotti, Marco; Mota, Claudia C B O; Nunes, Frederico Dias; Gomes, Anderson S L

2010-01-01T23:59:59.000Z

74

Graphene and Quantum Mechanics University of California, Berkeley  

E-Print Network [OSTI]

Graphene and Quantum Mechanics Minjae Lee University of California, Berkeley lee.minjae@math.berkeley.edu March 31, 2014 Minjae Lee (UC Berkeley) Graphene March 31, 2014 1 / 9 #12;Carbon structures Graphite 3 Berkeley) Graphene March 31, 2014 2 / 9 #12;Graphene Graphene A single layer of graphite The thinnest 2D

Zworski, Maciej

75

The bridge between classical and quantum mechanics from Fisher information  

E-Print Network [OSTI]

Fisher information measures a disorder system, which is specified by a corresponding probability, the likelihood. In this article, we provide a bridge to connect classical and quantum mechanics by using Fisher information. Following the principle of minimum Fisher information, we can derive the time-dependent Schr\\"odinger equation from Hamilton-Jacobi equation.

Tzu-Chao Hung

2014-07-31T23:59:59.000Z

76

DISCRETE QUANTUM MECHANICS AND THE SPEED OF LIGHT JOSEPH TOLES  

E-Print Network [OSTI]

DISCRETE QUANTUM MECHANICS AND THE SPEED OF LIGHT JOSEPH TOLES From S. McAdam, Unknowable Matters that nothing can travel faster than the speed of light. So instead of showing that it's impossible to determine the speed of light. 2. Associated Physics Photons are the smallest single unit of transverse electromagnetic

Morrow, James A.

77

E-Print Network 3.0 - accurate quantum mechanical Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

quantum mechanical Search Powered by Explorit Topic List Advanced Search Sample search results for: accurate quantum mechanical Page: << < 1 2 3 4 5 > >> 1 Special Session 3B New...

78

The Free-Will Postulate in Quantum Mechanics  

E-Print Network [OSTI]

The so-called "free will axiom" is an essential ingredient in many discussions concerning hidden variables in quantum mechanics. In this paper we argue that "free will" can be defined in different ways. The definition usually employed is clearly invalid in strictly deterministic theories. A different, more precise formulation is proposed here, defining a condition that may well be a more suitable one to impose on theoretical constructions and models. Our axiom, to be referred to as the `unconstrained initial state' condition, has consequences similar to "free will", but does not clash with determinism, and appears to lead to different conclusions concerning causality and locality in quantum mechanics. Models proposed earlier by this author fall in this category. Imposing our `unconstrained initial state' condition on a deterministic theory underlying Quantum Mechanics, appears to lead to a restricted free-will condition in the quantum system: an observer has the free will to modify the setting of a measuring device, but has no control over the phase of its wave function. The dismissal of the usual "free will" concept does not have any consequences for our views and interpretations of human activities in daily life, and the way our minds function, but it requires a more careful discussion on what, in practice, free will actually amounts to.

Gerard 't Hooft

2007-01-15T23:59:59.000Z

79

Developing the Deutsch-Hayden approach to quantum mechanics  

E-Print Network [OSTI]

The formalism of Deutsch and Hayden is a useful tool for describing quantum mechanics explicitly as local and unitary, and therefore quantum information theory as concerning a "flow" of information between systems. In this paper we show that these physical descriptions of flow are unique, and develop the approach further to include the measurement interaction and mixed states. We then give an analysis of entanglement swapping in this approach, showing that it does not in fact contain non-local effects or some form of superluminal signalling.

Clare Hewitt-Horsman; Vlatko Vedral

2006-09-12T23:59:59.000Z

80

The Inverse-Cube Central Force Field in Quantum Mechanics  

Science Journals Connector (OSTI)

The problem of the motion of a particle in an inverse-cube central force field is fully treated by quantum mechanics and the results compared with the classical theory. Taking the effective radial potential energy as Sr2, although the solutions for negative energy for 0?S?-h232?2? satisfy the usual boundary conditions, they can not be admitted because the Hamiltonian is not Hermitian in these solutions. This corresponds to taking (l+12)2 in place of l(l+1) as the analogue of the square of the classical angular momentum. If we do this, we get a complete analogy between the classical and quantum mechanically allowed solutions, with no quantization. The solutions involve Bessel functions of both real and imaginary orders with both real and imaginary arguments.

George H. Shortley

1931-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

ABOUT A HUNDRED YEARS HAVE PASSED since quantum mechanics was first developed. Quantum  

E-Print Network [OSTI]

is happening when an ob- servation is made on a system on the atomic level. In quantum mechanics a particle a point particle, but a wave, or something like a rip- pling of the water in a pond; a rippling that is si to Einstein's famous remark that "God does not play dice." Richard Feynman, in his 1967 book, The Character

Bier, Martin

82

Where the mathematical structure of Quantum Mechanics coms from  

E-Print Network [OSTI]

The mathematical formulation of Quantum Mechanics is derived from purely operational axioms based on a general definition of "experiment" as a set of transformations. The main ingredient of the mathematical construction is the postulated existence of "faithful states" that allows one to calibrate the experimental apparatus. Such notion is at the basis of the operational definitions of the scalar product and of the "adjoint" of a transformation.

Giacomo Mauro D'Ariano

2006-12-19T23:59:59.000Z

83

Toward quantum opto-mechanics in a gram-scale suspended mirror interferometer  

E-Print Network [OSTI]

A new generation of interferometric gravitational wave detectors, currently under construction, will closely approach the fundamental quantum limits of measurement, serving as a prominent example of quantum mechanics at ...

Wipf, Christopher (Christopher Conrad)

2013-01-01T23:59:59.000Z

84

Density Functional Theory (DFT) Simulated Annealing (SA)  

E-Print Network [OSTI]

. . . . . . . . 9 2009 #12;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory) % Lattice-Boltzmann (LBM) #12;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory (DFT;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory (DFT) Simulated Annealing (SA) Monte Carlo &$ ' ' (GCMC

85

Converting fructose to 5-hydroxymethylfurfural: A quantum mechanics/molecular mechanics study of the mechanism and energetics  

SciTech Connect (OSTI)

We studied the energetics of the closed-ring mechanism of the acid-catalysed dehydration of D-fructose to 5-hydroxymethylfurfural (HMF) by carrying out canonical ensemble free-energy calculations using bias-sampling, hybrid Quantum Mechanics/Molecular Mechanics Molecular Dynamics simulations with explicit water solvent at 363 K. The quantum mechanical calculations are performed at the PM3 theory level. We find that the reaction proceeds via intramolecular proton and hydride transfers. Solvent dynamics effects are analysed, and we show that the activation energy for the hydride transfers is due to re-organization of the polar solvent environment. We also find that in some instances intramolecular proton transfer is facilitated by mediating water, whereas in others the presence of quantum mechanical water has no effect. From a micro-kinetic point of view, we find that the rate-determining step of the reaction involves a hydride transfer prior to the third dehydration step, requiring an activation free energy of 31.8 kcal/mol, and the respective rate is found in good agreement with reported experimental values in zeolites. Thermodynamically, the reaction is exothermic by ?F=20.5kcal/mol.

Caratzoulas, S.; Vlachos, Dion G.

2011-01-01T23:59:59.000Z

86

Quantum Chemical Simulations Reveal Acetylene-Based Growth Mechanisms in the Chemical Vapor Deposition Synthesis of Carbon Nanotubes  

SciTech Connect (OSTI)

Nonequilibrium quantum chemical molecular dynamics (QM/MD) simulation of early stages in the nucleation process of carbon nanotubes from acetylene feedstock on an Fe38 cluster was performed based on the density-functional tight-binding (DFTB) potential. Representative chemical reactions were studied by complimentary static DFTB and density functional theory (DFT) calculations. Oligomerization and cross-linking reactions between carbon chains were found as the main reaction pathways similar to that suggested in previous experimental work. The calculations highlight the inhibiting effect of hydrogen for the condensation of carbon ring networks, and a propensity for hydrogen disproportionation, thus enriching the hydrogen content in already hydrogen-rich species and abstracting hydrogen content in already hydrogen-deficient clusters. The ethynyl radical C2H was found as a reactive, yet continually regenerated species, facilitating hydrogen transfer reactions across the hydrocarbon clusters. The nonequilibrium QM/MD simulations show the prevalence of a pentagon-first nucleation mechanism where hydrogen may take the role of one arm of an sp2 carbon Y-junction. The results challenge the importance of the metal carbide formation for SWCNT cap nucleation in the VLS model and suggest possible alternative routes following hydrogen-abstraction acetylene addition (HACA)-like mechanisms commonly discussed in combustion synthesis.

Eres, Gyula [ORNL] [ORNL; Wang, Ying [Nagoya University, Japan] [Nagoya University, Japan; Gao, Xingfa [Institute of High Energy Physics, Chinese Academy of Sciences, China] [Institute of High Energy Physics, Chinese Academy of Sciences, China; Qian, Hu-Jun [Jilin University, Changchun] [Jilin University, Changchun; Ohta, Yasuhito [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan] [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan; Wu, Xiaona [Nagoya University, Japan] [Nagoya University, Japan; Morokuma, Keiji [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan] [Fukui Institute of Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan; Irle, Stephan [WPI-Institute of Transformative Bio-Molecules and Department of Chemistry, Nagoya University, Japan] [WPI-Institute of Transformative Bio-Molecules and Department of Chemistry, Nagoya University, Japan

2014-01-01T23:59:59.000Z

87

Considering relativistic symmetry as the first principle of quantum mechanics  

E-Print Network [OSTI]

On the basis of the relativistic symmetry of Minkowski space, we derive a Lorentz invariant equation for a spread electron. This equation slightly differs from the Dirac equation and includes additional terms originating from the spread of an electron. Further, we calculate the anomalous magnetic moment based on these terms. These calculations do not include any divergence; therefore, renormalization procedures are unnecessary. In addition, the relativistic symmetry existing among coordinate systems will provide a new prospect for the foundations of quantum mechanics like the measurement process.

T. Kawahara

2007-04-20T23:59:59.000Z

88

The Hamilton-Jacobi Theory, Quantum Mechanics and General Relativity  

E-Print Network [OSTI]

The Hamilton-Jacobi theory of Classical Mechanics can be extended in a novel manner to systems which are fuzzy in the sense that they can be represented by wave functions. A constructive interference of the phases of the wave functions then gives us back Classical systems. In a suitable description this includes both Quantum Theory and General Relativity in the well known superspace formulation. However, there are several nuances which provide insight into these latter systems. All this is considered in this paper together with suitable generalization, to cascades of super universes.

B. G. Sidharth

2005-10-12T23:59:59.000Z

89

N + 1 dimensional quantum mechanical model for a closed universe  

E-Print Network [OSTI]

A quantum mechanical model for an N + 1 dimensional universe arising from a quantum fluctuation is outlined. (3 + 1) dimensions are a closed infinitely-expanding universe and the remaining N - 3 dimensions are compact. The (3 + 1) non-compact dimensions are modeled by quantizing a canonical Hamiltonian description of a homogeneous isotropic universe. It is assumed gravity and the strong-electro-weak (SEW) forces had equal strength in the initial state. Inflation occurred when the compact N -3 dimensional space collapsed after a quantum transition from the initial state of the univers, during its evolution to the present state where gravity is much weaker than the SEW force. The model suggests the universe has no singularities and the large size of our present universe is determined by the relative strength of gravity and the SEW force today. A small cosmological constant, resulting from the zero point energy of the scalar field corresponding to the compact dimensions, makes the model universe expand forever.

T. R. Mongan

1999-02-10T23:59:59.000Z

90

Hamilton relativity group for noninertial states in quantum mechanics  

E-Print Network [OSTI]

Physical states in quantum mechanics are rays in a Hilbert space. Projective representations of a relativity group transform between the quantum physical states that are in the admissible class. The physical observables of position, time, energy and momentum are the Hermitian representation of the Weyl-Heisenberg algebra. We show that there is a consistency condition that requires the relativity group to be a subgroup of the group of automorphisms of the Weyl-Heisenberg algebra. This, together with the requirement of the invariance of classical time, results in the inhomogeneous Hamilton group that is the relativity group for noninertial frames in classical Hamilton's mechanics. The projective representation of a group is equivalent to unitary representations of its central extension. The central extension of the inhomogeneous Hamilton group and its corresponding Casimir invariants are computed. One of the Casimir invariants is a generalized spin that is invariant for noninertial states. It is the familiar inertial Galilean spin with additional terms that may be compared to noninertial experimental results.

Stephen G. Low

2007-10-18T23:59:59.000Z

91

Mini-Proceedings ECT*: Speakable in quantum mechanics: atomic, nuclear and subnuclear physics tests  

E-Print Network [OSTI]

Mini-Proceedings ECT*: Speakable in quantum mechanics: atomic, nuclear and subnuclear physics tests, ECT*-Trento, 29 August - 2 September, 2011

C. Curceanu; J. Marton; E. Milotti

2011-12-06T23:59:59.000Z

92

Electronic structure of unsaturated ethers and thioethers by uv photoelectron spectroscopy andab initio quantum mechanical calculations  

Science Journals Connector (OSTI)

Ab initio quantum mechanical calculations and photoelectron (PE) spectroscopy measurements of ... and thioethers provided a reliable description of the electronic structure, in particular as far ...

G. Modena; F. Marcuzzi; E. Tondello; D. Aj

1988-12-01T23:59:59.000Z

93

The modern tools of quantum mechanics (A tutorial on quantum states, measurements, and operations)  

E-Print Network [OSTI]

This tutorial is devoted to review the modern tools of quantum mechanics, which are suitable to describe states, measurements, and operations of realistic, not isolated, systems in interaction with their environment, and with any kind of measuring and processing devices. We underline the central role of the Born rule and and illustrate how the notion of density operator naturally emerges, together the concept of purification of a mixed state. In reexamining the postulates of standard quantum measurement theory, we investigate how they may formally generalized, going beyond the description in terms of selfadjoint operators and projective measurements, and how this leads to the introduction of generalized measurements, probability operator-valued measures (POVM) and detection operators. We then state and prove the Naimark theorem, which elucidates the connections between generalized and standard measurements and illustrates how a generalized measurement may be physically implemented. The "impossibility" of a jo...

Paris, Matteo G A

2011-01-01T23:59:59.000Z

94

Quantum Mechanics and the Principle of Least Radix Economy  

E-Print Network [OSTI]

A new variational method, the principle of least radix economy, is formulated. The mathematical and physical relevance of the radix economy, also called digit capacity, is established, showing how physical laws can be derived from this concept in a unified way. The principle reinterprets and generalizes the principle of least action yielding two classes of physical solutions: least action paths and quantum wavefunctions. A new physical foundation of the Hilbert space of quantum mechanics is then accomplished and it is used to derive the Schr\\"odinger and Dirac equations and the breaking of the commutativity of spacetime geometry. The formulation provides an explanation of how determinism and random statistical behavior coexist in spacetime and a framework is developed that allows dynamical processes to be formulated in terms of chains of digits. These methods lead to a new (pre-geometrical) foundation for Lorentz transformations and special relativity. The Parker-Rhodes combinatorial hierarchy is encompassed within our approach and this leads to an estimate of the interaction strength of the electromagnetic and gravitational forces that agrees with the experimental values to an error of less than one thousandth. Finally, it is shown how the principle of least-radix economy naturally gives rise to Boltzmann's principle of classical statistical thermodynamics. A new expression for a general (path-dependent) nonequilibrium entropy is proposed satisfying the Second Law of Thermodynamics.

Vladimir Garcia-Morales

2015-01-08T23:59:59.000Z

95

Ad hoc physical Hilbert spaces in Quantum Mechanics  

E-Print Network [OSTI]

The overall principles of what is now widely known as PT-symmetric quantum mechanics are listed, explained and illustrated via a few examples. In particular, models based on an elementary local interaction V(x) are discussed as motivated by the naturally emergent possibility of an efficient regularization of an otherwise unacceptable presence of a strongly singular repulsive core in the origin. The emphasis is put on the constructive aspects of the models. Besides the overall outline of the formalism we show how the low-lying energies of bound states may be found in closed form in certain dynamical regimes. Finally, once these energies are found real we explain that in spite of a manifest non-Hermiticity of the Hamiltonian the time-evolution of the system becomes unitary in a properly amended physical Hilbert space.

Francisco M. Fernndez; Javier Garcia; Iveta Semordov; Miloslav Znojil

2014-05-28T23:59:59.000Z

96

Formal similarity between mathematical structures of electrodynamics and quantum mechanics  

E-Print Network [OSTI]

Electromagnetic phenomena can be described by Maxwell equations written for the vectors of electric and magnetic field. Equivalently, electrodynamics can be reformulated in terms of an electromagnetic vector potential. We demonstrate that the Schr\\"odinger equation admits an analogous treatment. We present a Lagrangian theory of a real scalar field $\\phi$ whose equation of motion turns out to be equivalent to the Schr\\"odinger equation with time independent potential. After introduction the field into the formalism, its mathematical structure becomes analogous to those of electrodynamics. The field $\\phi$ is in the same relation to the real and imaginary part of a wave function as the vector potential is in respect to electric and magnetic fields. Preservation of quantum-mechanics probability is just an energy conservation law of the field $\\phi$.

A. A. Deriglazov

2011-05-07T23:59:59.000Z

97

Testing axioms for Quantum Mechanics on Probabilistic toy-theories  

E-Print Network [OSTI]

In Ref. [1] one of the authors proposed postulates for axiomatizing Quantum Mechanics as a "fair operational framework", namely regarding the theory as a set of rules that allow the experimenter to predict future events on the basis of suitable tests, having local control and low experimental complexity. In addition to causality, the following postulates have been considered: PFAITH (existence of a pure preparationally faithful state), and FAITHE (existence of a faithful effect). These postulates have exhibited an unexpected theoretical power, excluding all known nonquantum probabilistic theories. Later in Ref. [2] in addition to causality and PFAITH, postulate LDISCR (local discriminability) and PURIFY (purifiability of all states) have been considered, narrowing the probabilistic theory to something very close to Quantum Mechanics. In the present paper we test the above postulates on some nonquantum probabilistic models. The first model, "the two-box world" is an extension of the Popescu-Rohrlich model, which achieves the greatest violation of the CHSH inequality compatible with the no-signaling principle. The second model "the two-clock world" is actually a full class of models, all having a disk as convex set of states for the local system. One of them corresponds to the "the two-rebit world", namely qubits with real Hilbert space. The third model--"the spin-factor"--is a sort of n-dimensional generalization of the clock. Finally the last model is "the classical probabilistic theory". We see how each model violates some of the proposed postulates, when and how teleportation can be achieved, and we analyze other interesting connections between these postulate violations, along with deep relations between the local and the non-local structures of the probabilistic theory.

Giacomo Mauro D'Ariano; Alessandro Tosini

2009-11-29T23:59:59.000Z

98

A fully 3D atomistic quantum mechanical study on random dopant induced effects in 25nm MOSFETs  

E-Print Network [OSTI]

A Fully 3D Atomistic Quantum Mechanical Study on RandomWang* Abstract We present a fully 3D atomistic quantum me-Dopant ?uctuation, MOSFETs, 3D, threshold, LCBB, quantum

Jiang, Xiang-Wei

2008-01-01T23:59:59.000Z

99

Quantum Mechanics Action of ELF Electromagnetic Fields on Living Organisms  

Science Journals Connector (OSTI)

There is presently an intense discussion if extremely low frequency electromagnetic field (ELF?EMF) exposure has consequences for human health. This include exposure to structures and appliances from this range of frequency in the electromagnetic (EM) spectrum. Biological effects of such exposures have been noted frequently although the implications for specific health effects is not that clear. The basic interactions mechanisms between such fields and living matter is unknown. Numerous hypotheses have been suggested although none is convincingly supported by experimental data. Various cellular components processes and systems can be affected by EMF exposure. Since it is unlikely that EMF can induce DNA damage directly most studies have examined EMF effects on the cell membrane level general and specific gene expression and signal transduction pathways. Even more a large number of studies have been performed regarding cell proliferation cell cycle regulation cell differentiation metabolism and various physiological characteristics of cells. The aim of this letter is present the hypothesis of a possible quantum mechanic effect generated by the exposure of ELF EMF an event which is compatible with the multitude of effects observed after exposure. Based on an extensive literature review we suggest that ELF EMF exposure is able to perform such activation restructuring the electronic level of occupancy of free radicals in molecules interacting with DNA structures.

J. J. Godina?Nava

2010-01-01T23:59:59.000Z

100

Probabilistic theories: what is special about Quantum Mechanics?  

E-Print Network [OSTI]

Quantum Mechanics (QM) is a very special probabilistic theory, yet we don't know which operational principles make it so. All axiomatization attempts suffer at least one postulate of a mathematical nature. Here I will analyze the possibility of deriving QM as the mathematical representation of a "fair operational framework", i.e. a set of rules which allows the experimenter to make predictions on future "events" on the basis of suitable "tests", e.g. without interference from uncontrollable sources. Two postulates need to be satisfied by any fair operational framework: NSF: "no-signaling from the future"--for the possibility of making predictions on the basis of past tests; PFAITH: "existence of a preparationally faithful state"--for the possibility of preparing any state and calibrating any test. I will show that all theories satisfying NSF admit a C*-algebra representation of events as linear transformations of effects. Based on a very general notion of dynamical independence, it is easy to see that all such probabilistic theories are "non-signaling without interaction" ("non-signaling" for short)--another requirement for a fair operational framework. Postulate PFAITH then implies the "local observability principle", the tensor-product structure for the linear spaces of states and effects, the impossibility of bit commitment and additional features, such an operational definition of transpose, a scalar product for effects, weak-selfduality of the theory, and more. Dual to Postulate PFAITH an analogous postulate for effects would give additional quantum features, such as teleportation. However, all possible consequences of these postulates still need to be investigated, and it is not clear yet if we can derive QM from the present postulates only. [CONTINUES on manuscript

Giacomo Mauro D'Ariano

2008-07-28T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

The Superposition Principle in Quantum Mechanics - did the rock enter the foundation surreptitiously?  

E-Print Network [OSTI]

The superposition principle forms the very backbone of quantum theory. The resulting linear structure of quantum theory is structurally so rigid that tampering with it may have serious, seemingly unphysical, consequences. This principle has been succesful at even the highest available accelerator energies. Is this aspect of quantum theory forever then? The present work is an attempt to understand the attitude of the founding fathers, particularly of Bohr and Dirac, towards this principle. The Heisenberg matrix mechanics on the one hand, and the Schrodinger wave mechanics on the other, are critically examined to shed light as to how this principle entered the very foundations of quantum theory.

N. D. Hari Dass

2013-11-18T23:59:59.000Z

102

The Superposition Principle in Quantum Mechanics - did the rock enter the foundation surreptitiously?  

E-Print Network [OSTI]

The superposition principle forms the very backbone of quantum theory. The resulting linear structure of quantum theory is structurally so rigid that tampering with it may have serious, seemingly unphysical, consequences. This principle has been succesful at even the highest available accelerator energies. Is this aspect of quantum theory forever then? The present work is an attempt to understand the attitude of the founding fathers, particularly of Bohr and Dirac, towards this principle. The Heisenberg matrix mechanics on the one hand, and the Schrodinger wave mechanics on the other, are critically examined to shed light as to how this principle entered the very foundations of quantum theory.

Dass, N D Hari

2013-01-01T23:59:59.000Z

103

Renninger's Thought Experiment: Implications for Quantum Ontology and for Quantum Mechanic's Interpretation  

E-Print Network [OSTI]

It is argued that the conclusions obtained by Renninger (Zeitschrift fur Physik 136, 251 (1953)), by means of an interferometer thought experiment, have important implications for a number of still ongoing discussions about quantum mechanics (QM). To these belong the ontology underlying QM, Bohr's complementarity principle, the significance of QM's wave function, the "elements of reality" introduced by Einstein, Podolsky and Rosen (EPR), and Bohm's version of QM (BQM). A slightly extended setup is used to make a physical prediction at variance with the mathematical prediction of QM. An english translation of Renninger's paper, which was originally published in german language, follows the present paper. This should facilitate access to that remarkable, apparently overlooked and forgotten, paper.

De Baere, W

2005-01-01T23:59:59.000Z

104

Frequency-domain multiscale quantum mechanics/electromagnetics simulation method  

SciTech Connect (OSTI)

A frequency-domain quantum mechanics and electromagnetics (QM/EM) method is developed. Compared with the time-domain QM/EM method [Meng et al., J. Chem. Theory Comput. 8, 11901199 (2012)], the newly developed frequency-domain QM/EM method could effectively capture the dynamic properties of electronic devices over a broader range of operating frequencies. The system is divided into QM and EM regions and solved in a self-consistent manner via updating the boundary conditions at the QM and EM interface. The calculated potential distributions and current densities at the interface are taken as the boundary conditions for the QM and EM calculations, respectively, which facilitate the information exchange between the QM and EM calculations and ensure that the potential, charge, and current distributions are continuous across the QM/EM interface. Via Fourier transformation, the dynamic admittance calculated from the time-domain and frequency-domain QM/EM methods is compared for a carbon nanotube based molecular device.

Meng, Lingyi; Yin, Zhenyu; Yam, ChiYung, E-mail: yamcy@yangtze.hku.hk, E-mail: ghc@everest.hku.hk; Koo, SiuKong; Chen, GuanHua, E-mail: yamcy@yangtze.hku.hk, E-mail: ghc@everest.hku.hk [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong)] [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong); Chen, Quan; Wong, Ngai [Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong)] [Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong)

2013-12-28T23:59:59.000Z

105

The symmetry groups of noncommutative quantum mechanics and coherent state quantization  

SciTech Connect (OSTI)

We explore the group theoretical underpinning of noncommutative quantum mechanics for a system moving on the two-dimensional plane. We show that the pertinent groups for the system are the two-fold central extension of the Galilei group in (2+1)-space-time dimensions and the two-fold extension of the group of translations of R{sup 4}. This latter group is just the standard Weyl-Heisenberg group of standard quantum mechanics with an additional central extension. We also look at a further extension of this group and discuss its significance to noncommutative quantum mechanics. We build unitary irreducible representations of these various groups and construct the associated families of coherent states. A coherent state quantization of the underlying phase space is then carried out, which is shown to lead to exactly the same commutation relations as usually postulated for this model of noncommutative quantum mechanics.

Chowdhury, S. Hasibul Hassan; Ali, S. Twareque [Department of Mathematics and Statistics, Concordia University, Montreal, Quebec H3G 1M8 (Canada)] [Department of Mathematics and Statistics, Concordia University, Montreal, Quebec H3G 1M8 (Canada)

2013-03-15T23:59:59.000Z

106

Density matrix and dynamical aspects of Quantum Mechanics with Fundamental Length  

E-Print Network [OSTI]

In this paper Quantum Mechanics with Fundamental Length is built as a deformation of Quantum Mechanics. To this aim an approach is used which does not take into account commutator deformation as usually it is done, but density matrix deformation. The corresponding deformed density matrix, which is called density pro-matrix is given explicitly. It properties have been investigated as well as some dynamical aspects of the theory. In particular, the deformation of Liouville equation is analyzed in detail. It was shown that Liouville equation in Quantum Mechanics appears as a low energy limit of deformed Liouville equation in Quantum Mechanics with Fundamental Length. Some implications of obtained results are presented as well as their application to the calculation of black hole entropy.

A. E. Shalyt-Margolin; J. G. Suarez

2002-11-25T23:59:59.000Z

107

Quantum-mechanical description of Lense-Thirring effect for relativistic scalar particles  

E-Print Network [OSTI]

Exact expression for the Foldy-Wouthuysen Hamiltonian of scalar particles is used for a quantum-mechanical description of the relativistic Lense-Thirring effect. The exact evolution of the angular momentum operator in the Kerr field approximated by a spatially isotropic metric is found. The quantum-mechanical description of the full Lense-Thirring effect based on the Laplace-Runge-Lenz vector is given in the nonrelativistic and weak-field approximation. Relativistic quantum-mechanical equations for the velocity and acceleration operators are obtained. The equation for the acceleration defines the Coriolis-like and centrifugal-like accelerations and presents the quantum-mechanical description of the frame-dragging effect.

Alexander J. Silenko

2014-08-10T23:59:59.000Z

108

Quantum mechanical analogue of the zeroth law of thermodynamics. (On the problem of incorporating Thermodynamics into Quantum Theory)  

E-Print Network [OSTI]

This approach to the incorporation of stochastic thermodynamics into quantum theory is based on the conception of consistent inclusion of the holistic stochastic environmental influence described by wave functions of the arbitrary vacuum, which was proposed in our paper previously. In this study, we implement the possibility of explicitly incorporating the zeroth law of stochastic thermodynamics in the form of the saturated Schr\\"odinger uncertainty relation into quantum theory. This allows comparatively analyzing the sets of states of arbitrary vacuums, namely, squeezed coherent states (SCSs) and correlated coherent states (CCSs). In addition, we compare the results of the construction of stochastic thermodynamics using SCSs and TCCSs with the versions involving the incorporation of thermodynamics into quantum theory developed previously and based on thermofield dynamics and quantum statistical mechanics.

O. N. Golubjeva; A. D. Sukhanov

2013-03-25T23:59:59.000Z

109

Calculus for Functions of Noncommuting Operators and General Phase-Space Methods in Quantum Mechanics. II. Quantum Mechanics in Phase Space  

Science Journals Connector (OSTI)

In Paper I of this investigation a new calculus for functions of noncommuting operators was developed, based on the notion of mapping of operators onto c-number functions. With the help of this calculus, a general theory is formulated, in the present paper, of phase-space representation of quantum-mechanical systems. It is shown that there is a whole class of such representations, one associated with each type of mapping, the simplest one being the well-known representation due to Weyl. For each representation, the quantum-mechanical expectation value of an operator is found to be expressible in the form of a phase-space average of classical statistical mechanics. The phase-space distribution functions are, however, not true probabilities, in general. The phase-space forms of the main quantum-mechanical equations of motion are obtained and are found to have the form of a generalized Liouville equation. The phase-space form of the Bloch equation for the density operator of a quantum system in thermal equilibrium is also derived. The generalized characteristic functions of boson systems are defined and their main properties are studied. The equations of motion for the characteristic functions are also derived. As an illustration of the theory, a generalized stochastic description of a quantized electromagnetic field is obtained.

G. S. Agarwal and E. Wolf

1970-11-15T23:59:59.000Z

110

The Role of Magnesium for Geometry and Charge in GTP Hydrolysis, Revealed by Quantum Mechanics/Molecular Mechanics Simulations  

E-Print Network [OSTI]

The Role of Magnesium for Geometry and Charge in GTP Hydrolysis, Revealed by Quantum Mechanics, People's Republic of China ABSTRACT The coordination of the magnesium ion in proteins by triphosphates conversion. For example, in Ras the magnesium ion contributes to the catalysis of GTP hydrolysis

Gerwert, Klaus

111

Hybrid Quantum Mechanical and Molecular Mechanics Study of the SN2 Reaction of CCl4 + OH? in Aqueous Solution: The Potential of Mean Force, Reaction Energetics, and Rate Constants  

SciTech Connect (OSTI)

The bimolecular nucleophilic substitution reaction of CCl{sub 4} and OH{sup -} in aqueous solution was investigated on the basis of a combined quantum mechanical and molecular mechanics method. A multilayered representation approach is employed to achieve high accuracy results at the CCSD(T) level of theory. The potential of mean force calculations at the DFT level and CCSD(T) level of theory yield reaction barrier heights of 22.7 and 27.9 kcal/mol, respectively. Both the solvation effects and the solvent-induced polarization effect have significant contributions to the reaction energetics, for example, the solvation effect raises the saddle point by 10.6 kcal/mol. The calculated rate constant coefficient is 8.6 x 10{sup -28} cm{sup 3} molecule{sup -1} s{sup -1} at the standard state condition, which is about 17 orders magnitude smaller than that in the gas phase. Among the four chloromethanes (CH{sub 3}Cl, CH{sub 2}Cl{sub 2}, CHCl{sub 3}, and CCl{sub 4}), CCl{sub 4} has the lowest free energy activation barrier for the reaction with OH{sup -1} in aqueous solution, confirming the trend that substitution of Cl by H in chloromethanes diminishes the reactivity.

Wang, Ting; Yin, Hongyun; Wang, Dunyou; Valiev, Marat

2012-02-16T23:59:59.000Z

112

Quantum mechanical aspects of friction and electric resistance in microscopic problems with applications to radiation physics  

E-Print Network [OSTI]

Friction incorporates the close connection between classical mechanics in irreversible thermodynamics. The translation to a quantum mechanical foundation is not trivial and requires a generalization of the Lagrange function. A change to electromagnetic circuits appears to more adequate, since the electric analogue (Ohms law) is related to scatter of electrons at lattice vibrations.

Ulmer, W

2015-01-01T23:59:59.000Z

113

Self-field and magnetic-flux quantum mechanics  

E-Print Network [OSTI]

Self-field and quantized magnetic-flux are employed to generate the quantum numbers n, m, and l of atomic physics. Wave-particle duality is shown to be a natural outcome of having a particle and its self-field.

Paul Harris

2005-04-06T23:59:59.000Z

114

http://chem.ps.uci.edu/~kieron/dft/book/ The ABC of DFT  

E-Print Network [OSTI]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 II Basics 55 6 Density functional theory 57 6.1 One electron1 http://chem.ps.uci.edu/~kieron/dft/book/ The ABC of DFT Kieron Burke and friends Department.6 Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2 Functionals 27 2

Burke, Kieron

115

The Hydrogen Atom: a Review on the Birth of Modern Quantum Mechanics  

E-Print Network [OSTI]

The purpose of this work is to retrace the steps that were made by scientists of XIX century, like Bohr, Schrodinger, Heisenberg, Pauli, Dirac, for the formulation of what today represents the modern quantum mechanics and that, within two decades, put in question the classical physics. In this context, the study of the electronic structure of hydrogen atom has been the main starting point for the formulation of the theory and, till now, remains the only real case for which the quantum equation of motion can be solved exactly. The results obtained by each theory will be discussed critically, highlighting limits and potentials that allowed the further development of the quantum theory.

Nanni, Luca

2015-01-01T23:59:59.000Z

116

Probing mechanical quantum coherence with an ultracold-atom meter  

SciTech Connect (OSTI)

We propose a scheme to probe quantum coherence in the state of a nanocantilever based on its magnetic coupling (mediated by a magnetic tip) with a spinor Bose Einstein condensate (BEC). By mapping the BEC into a rotor, its coupling with the cantilever results in a gyroscopic motion whose properties depend on the state of the cantilever: the dynamics of one of the components of the rotor angular momentum turns out to be strictly related to the presence of quantum coherence in the state of the cantilever. We also suggest a detection scheme relying on Faraday rotation, which produces only a very small back-action on the BEC and is thus suitable for a continuous detection of the cantilever's dynamics.

Lo Gullo, N.; Busch, Th. [Department of Physics, University College Cork, Cork (Ireland); Palma, G. M. [NEST Istituto Nanoscienze-CNR and Dipartimento di Fisica, Univerisita' degli Studi di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Paternostro, M. [Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN (United Kingdom)

2011-12-15T23:59:59.000Z

117

Point Transformations in Quantum Mechanics. II. Solving for the Generators  

Science Journals Connector (OSTI)

We generalize the method and the results of paper I (G. Carmi, preceding paper) to find the generators of a point transformation which maps the xi, i=1,,n, into any set of functions ?i(x1,,xn), i=1,,n, within a certain, quite wide family, for which these generators can be written in closed form, with the object of applications to a quantum many-body method developed by Gross et al.

Gideon Carmi

1973-02-15T23:59:59.000Z

118

Modelling Quantum Mechanics by the Quantumlike Description of the Electric Signal Propagation in Transmission Lines  

E-Print Network [OSTI]

It is shown that the transmission line technology can be suitably used for simulating quantum mechanics. Using manageable and at the same time non-expensive technology, several quantum mechanical problems can be simulated for significant tutorial purposes. The electric signal envelope propagation through the line is governed by a Schrodinger-like equation for a complex function, representing the low-frequency component of the signal, In this preliminary analysis, we consider two classical examples, i.e. the Frank-Condon principle and the Ramsauer effect.

R. Fedele; M. A. Man'ko; V. I. Man'ko; V. G. Vaccaro

2002-07-30T23:59:59.000Z

119

Parametric self pulsing in a quantum opto-mechanical system  

E-Print Network [OSTI]

We describe an opto-mechanical system in which the coupling between optical and mechanical degrees of freedom takes the form of a fully quantised third-order parametric interaction. Two physical realisations are proposed: a harmonically trapped atom in a standing wave and the `membrane in the middle' model. The dominant resonant interaction corresponds to a stimulated Raman process in which two phonons are converted into a single cavity photon. We show that this system can exhibit a stable limit cycle in which energy is periodically exchanged between optical and mechanical degrees of freedom. This is equivalently described as a parametric self-pulsing.

Holmes, C A

2009-01-01T23:59:59.000Z

120

Near quantitative agreement of model free DFT- MD predictions...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Near quantitative agreement of model free DFT- MD predictions with XAFS observations of the hydration structure of highly Near quantitative agreement of model free DFT- MD...

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Chemical dynamics in the gas phase: Time-dependent quantum mechanics of chemical reactions  

SciTech Connect (OSTI)

A major goal of this research is to obtain an understanding of the molecular reaction dynamics of three and four atom chemical reactions using numerically accurate quantum dynamics. This work involves: (i) the development and/or improvement of accurate quantum mechanical methods for the calculation and analysis of the properties of chemical reactions (e.g., rate constants and product distributions), and (ii) the determination of accurate dynamical results for selected chemical systems, which allow one to compare directly with experiment, determine the reliability of the underlying potential energy surfaces, and test the validity of approximate theories. This research emphasizes the use of recently developed time-dependent quantum mechanical methods, i.e. wave packet methods.

Gray, S.K. [Argonne National Laboratory, IL (United States)

1993-12-01T23:59:59.000Z

122

Is Bell's theorem relevant to quantum mechanics? On locality and non-commuting observables  

E-Print Network [OSTI]

Bell's theorem is a statement by which averages obtained from specific types of statistical distributions must conform to a family of inequalities. These models, in accordance with the EPR argument, provide for the simultaneous existence of quantum mechanically incompatible quantities. We first recall several contradictions arising between the assumption of a joint distribution for incompatible observables and the probability structure of quantum-mechanics, and conclude that Bell's theorem is not expected to be relevant to quantum phenomena described by non-commuting observables, irrespective of the issue of locality. Then, we try to disentangle the locality issue from the existence of joint distributions by introducing two models accounting for the EPR correlations but denying the existence of joint distributions. We will see that these models do not need to resort explicitly to non-locality: the first model relies on conservation laws for ensembles, and the second model on an equivalence class by which different configurations lead to the same physical predictions.

A. Matzkin

2009-01-12T23:59:59.000Z

123

Energy Down Conversion between Classical Electromagnetic Fields via a Quantum Mechanical SQUID Ring  

E-Print Network [OSTI]

We consider the interaction of a quantum mechanical SQUID ring with a classical resonator (a parallel $LC$ tank circuit). In our model we assume that the evolution of the ring maintains its quantum mechanical nature, even though the circuit to which it is coupled is treated classically. We show that when the SQUID ring is driven by a classical monochromatic microwave source, energy can be transferred between this input and the tank circuit, even when the frequency ratio between them is very large. Essentially, these calculations deal with the coupling between a single macroscopic quantum object (the SQUID ring) and a classical circuit measurement device where due account is taken of the non-perturbative behaviour of the ring and the concomitant non-linear interaction of the ring with this device.

M. J. Everitt; T. D. Clark; P. B. Stiffell; C. J. Harland; J. F. Ralph

2005-05-16T23:59:59.000Z

124

Prog. Theor. Phys. Suppl. 138, 489 -494 (2000) Quantum Statistical Mechanics on a Quantum Computer  

E-Print Network [OSTI]

the eigenvalues of the model Hamiltonian may be determined. We test our QA on a software implemention of a 21 by running this algorithm on a software implementation of a 21-qubit quantum computer for the case phenomena.11) For future applications it is clearly of interest to address the question how to program a QC

125

Quantum mechanics of the free Dirac electrons and Einstein photons, and the Cauchy process  

E-Print Network [OSTI]

Fundamental solutions for the free Dirac electron and Einstein photon equations in position coordinates are constructed as matrix valued functionals on the space of bump functions. It is shown that these fundamental solutions are related by a unitary transform via the Cauchy distribution in imaginary time. We study the way the classical relativistic mechanics of the free particle comes from the quantum mechanics of the free Dirac electron.

A. A. Beilinson

2014-12-03T23:59:59.000Z

126

Non-locality and gauge freedom in Deutsch and Hayden's formulation of quantum mechanics  

E-Print Network [OSTI]

Deutsch and Hayden have proposed an alternative formulation of quantum mechanics which is completely local. We argue that their proposal must be understood as having a form of `gauge freedom' according to which mathematically distinct states are physically equivalent. Once this gauge freedom is taken into account, their formulation is no longer local.

David Wallace; Chris Timpson

2005-03-16T23:59:59.000Z

127

Operational axioms for a C*-algebraic formulation of Quantum Mechanics  

E-Print Network [OSTI]

A C*-algebra formulation of Quantum Mechanics is derived from purely operational axioms in which the primary role is played by the "transformations" that the system undergoes in the course of an "experiment". The notion of the {\\em adjoint} of a transformation is based on the postulated existence of "faithful states" that allows one to calibrate the experimental apparatus.

Giacomo Mauro D'Ariano

2007-01-29T23:59:59.000Z

128

Neutron Interferometry: Lessons in Experimental Quantum Mechanics Helmut Rauch and Samuel A. Werner  

E-Print Network [OSTI]

Neutron Interferometry: Lessons in Experimental Quantum Mechanics Helmut Rauch and Samuel A. Werner Today, 55, 52 (2002). The copious availability of thermalized neutrons makes them an ideal probe of choice for many fundamental physics investigations. A prime example is the field of neutron

Lynn, Jeffrey W.

129

Philosophy of mind and the problem of free will in the light of quantum mechanics  

E-Print Network [OSTI]

Defects occasioned by the advent of quantum mechanics are described in detail of recent arguments by John Searle and by Jaegwon Kim pertaining to the question of the complete reducibility to the physical of the apparent capacity of a person's conscious thoughts to affect the behaviour of that person's physically described brain.

Henry P. Stapp

2008-05-01T23:59:59.000Z

130

Philosophy of Mind and the Problem of FreeWill in the Light of Quantum Mechanics.  

SciTech Connect (OSTI)

Arguments pertaining to the mind-brain connection and to the physical effectiveness of our conscious choices have been presented in two recent books, one by John Searle, the other by Jaegwon Kim. These arguments are examined, and it is argued that the difficulties encountered arise from a defective understanding and application of a pertinent part of contemporary science, namely quantum mechanics.

Stapp, Henry; Stapp, Henry P

2008-04-01T23:59:59.000Z

131

The third law of thermodynamics, the unattainability of absolute zero, and quantum mechanics  

Science Journals Connector (OSTI)

The third law of thermodynamics, the unattainability of absolute zero, and quantum mechanics ... Usual statements of the third law may cause many students to draw the erroneous conclusion that the third law is a very weak statement of general applicability or a strong positive statement that applies in only a vanishingly small number of cases. ... Thermodynamics ...

Ernest M. Loebl

1960-01-01T23:59:59.000Z

132

Carbon 40 (2002) 429436 Quantum-mechanical simulations of field emission from carbon  

E-Print Network [OSTI]

Carbon 40 (2002) 429­436 Quantum-mechanical simulations of field emission from carbon nanotubes *A simulations of field emission from 2-nm long open (5,5), closed (5,5) and open (10,0) carbon nanotubes recently where the carbon nanotubes [1,2], a vast literature has appeared on field-emission current from

Mayer, Alexandre

133

Orthogonal-state-based cryptography in quantum mechanics and local post-quantum theories  

E-Print Network [OSTI]

In contrast to the well-known quantum key distribution (QKD) protocols, which encode secret bits in non-orthogonal states, orthogonal-state-based protocols for QKD transmit secret bits deterministically. Even though secure, such a protocol cannot be used to transmit a secret message directly, because an eavesdropper is not prevented from learning something about the direct message before being detected. A quantum secure direct communication (QSDC) scheme satisfies this stronger security requirement. In this work, we study the relationship between security in QKD and QSDC. We show that replacing qubit streaming in a QKD scheme by block-encoding of qubits, we can construct a QSDC scheme. This forms the basis for reducing the security of a QSDC scheme to that of aQKD scheme, in the sense that if the latter is secure, then so is the QSDC scheme built on top of it. We refer to this as \\textit{block reduction}. Further, we show that the security of QKD reduces to that of QSDC, in the sense that if a QSDC protocol is secure, then by sending a random key as the direct message, the corresponding QKD protocol is also secure. This procedure we call as \\textit{key reduction}. Finally, we propose an orthogonal-state-based deterministic key distribution (KD) protocol which is secure in some local post-quantum theories. Its security arises neither from geographic splitting of a code state nor from Heisenberg uncertainty, but from post-measurement disturbance.

S. Arvinda; Anindita Banerjee; Anirban Pathak; R. Srikanth

2014-09-30T23:59:59.000Z

134

Quantum discord is Bohr's notion of non-mechanical disturbance introduced in his answer to EPR  

E-Print Network [OSTI]

By rigorously formalizing the Einstein-Podolsky-Rosen (EPR) argument, and Bohr's reply, one can appreciate that both arguments were technically correct. Their opposed conclusions about the completeness of quantum mechanics hinged upon an explicit difference in their criteria for when a measurement on Alice's system can be regarded as not disturbing Bob's system. The EPR criteria allow their conclusion (incompletness) to be reached by establishing the physical reality of just a single observable $q$ (not a conjugate pair $q$ and $p$), but I show that Bohr's definition of disturbance prevents the EPR chain of reasoning from establishing even this. Moreover, I show that Bohr's definition is intimately related to the asymmetric concept of quantum discord from quantum information theory: if and only if the joint state has no Alice-discord, she can measure any observable without disturbing (in Bohr's sense) Bob's system. Discord can be present even when systems are unentangled, and this has implications for our und...

Wiseman, Howard M

2013-01-01T23:59:59.000Z

135

Structure/Function Studies of Proteins Using Linear Scaling Quantum Mechanical Methodologies  

SciTech Connect (OSTI)

We developed a linear-scaling semiempirical quantum mechanical (QM) program (DivCon). Using DivCon we can now routinely carry out calculations at the fully QM level on systems containing up to about 15 thousand atoms. We also implemented a Poisson-Boltzmann (PM) method into DivCon in order to compute solvation free energies and electrostatic properties of macromolecules in solution. This new suite of programs has allowed us to bring the power of quantum mechanics to bear on important biological problems associated with protein folding, drug design and enzyme catalysis. Hence, we have garnered insights into biological systems that have been heretofore impossible to obtain using classical simulation techniques.

Merz, K. M.

2004-07-19T23:59:59.000Z

136

Growth Mechanisms and Kinetics of Gibbsite Crystallization: Experimental and Quantum Chemical Study  

Science Journals Connector (OSTI)

Growth Mechanisms and Kinetics of Gibbsite Crystallization: Experimental and Quantum Chemical Study ... A central, 4 blade, 45, pitch turbine impeller driven by a 70 W, multispeed motor provided a constant agitation speed of 400 rpm and a fully developed axial flow with a high degree of suspension uniformity in the crystallizer. ... The exact role of the oleate ion with respect to surface bonding needs further study and will be pursued in future investigations. ...

Jun Li; Jonas Addai-Mensah; Alagu Thilagam; Andrea R. Gerson

2012-05-17T23:59:59.000Z

137

How to Derive the Hilbert-Space Formulation of Quantum Mechanics From Purely Operational Axioms  

E-Print Network [OSTI]

In the present paper I show how it is possible to derive the Hilbert space formulation of Quantum Mechanics from a comprehensive definition of "physical experiment" and assuming "experimental accessibility and simplicity" as specified by five simple Postulates. This accomplishes the program presented in form of conjectures in the previous paper quant-ph/0506034. Pivotal roles are played by the "local observability principle", which reconciles the holism of nonlocality with the reductionism of local observation, and by the postulated existence of "informationally complete observables" and of a "symmetric faithful state". This last notion allows one to introduce an operational definition for the real version of the "adjoint"--i. e. the transposition--from which one can derive a real Hilbert-space structure via either the Mackey-Kakutani or the Gelfand-Naimark-Segal constructions. Here I analyze in detail only the Gelfand-Naimark-Segal construction, which leads to a real Hilbert space structure analogous to that of (classes of generally unbounded) selfadjoint operators in Quantum Mechanics. For finite dimensions, general dimensionality theorems that can be derived from a local observability principle, allow us to represent the elements of the real Hilbert space as operators over an underlying complex Hilbert space (see, however, a still open problem at the end of the paper). The route for the present operational axiomatization was suggested by novel ideas originated from Quantum Tomography.

Giacomo Mauro D'Ariano

2006-03-02T23:59:59.000Z

138

Screened Hybrid and DFT + U Studies of the Structural, Electronic...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Screened Hybrid and DFT + U Studies of the Structural, Electronic, and Optical Properties of U3O8. Screened Hybrid and DFT + U Studies of the Structural, Electronic, and Optical...

139

Finding way to bridge the gap between quantum and classical mechanics  

E-Print Network [OSTI]

We have calculated the momentum distributions of nanoparticles in diffraction and interference dependent on the effective screening mass parameter or size parameter and presented the calculations for a nanoparticle inside an infinite square potential well and for a tunnelling nanoparticle through a square potential barrier. These results display the transition from quantum to classical mechanics and the simultaneous wave-particle duality of nanoparticles. The concept that the effective screening effect increases with increasing size of an object paves way for development of nanomechanics and nanotechnology.

Wang Guowen

2005-12-12T23:59:59.000Z

140

Quantum mechanical constraints on the measurement of the density of the electromagnetic energy  

E-Print Network [OSTI]

It is considered constraints imposed by the quantum mechanics on the measurement of the density of the electromagnetic energy. First, the energy of the electromagnetic wave and the volume (time) are bound with the Heisenberg uncertainty principle. It reduces from double to ordinary the relativistic effect for the density of the electromagnetic energy. Second, the frequency of photons and the number of photons are bound with the Heisenberg uncertainty principle. Then relativistic effects for the frequency of photons and for the number of photons are incompatible.

D. L. Khokhlov

2004-02-05T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Probing the quantum-mechanical equivalent-photon spectrum for electromagnetic dissociation of relativistic uranium projectiles  

E-Print Network [OSTI]

Electromagnetic fission cross sections for the reactions U + (Be, C, Al, Cu, In, Au, U) at E/A = 0.6 and 1.0 GeV are compared to theoretical calculations using recently proposed quantum-mechanical equivalent-photon spectra. In contrast to semi-classical calculations, systematically lower cross sections are obtained that cannot reproduce the experimental results. Furthermore, we point out that the study of electromagnetic fission cross sections or electromagnetic 1-neutron removal cross sections alone cannot provide unambiguous information on the excitation of the double giant dipole resonance.

Th. Rubehn; W. F. J. Mueller; W. Trautmann

1996-12-06T23:59:59.000Z

142

Quantum mechanics forbids an initial or final singularity in a closed FRW universe  

E-Print Network [OSTI]

The existence of singularities in a closed FRW universe depends on the assumption that general relativity is valid for distances less than the Planck length. However, stationary state wave functions of the Schrodinger equation for a closed radiation-dominated FRW universe derived by Elbaz et al (General Relativity and Gravitation 29, 481, 1997) are zero at zero radius of curvature. Thus, even if general relativity is assumed valid at distances less than the Planck length, quantum mechanics seems to forbid singularities in a closed FRW universe.

T. R. Mongan

1999-03-07T23:59:59.000Z

143

Effect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed and on-the-fly kinetic  

E-Print Network [OSTI]

viewpoints, is futile. Among several mechanisms proposed for hydrogen embrittlement (HE) of metals, hydrogenEffect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed-assisted diffusion and trapping of hydrogen by crystalline defects in iron. Given an embedded atom (EAM) potential

Ortiz, Michael

144

Spin Matrix Theory: A quantum mechanical model of the AdS/CFT correspondence  

E-Print Network [OSTI]

We introduce a new quantum mechanical theory called Spin Matrix theory (SMT). The theory is interacting with a single coupling constant g and is based on a Hilbert space of harmonic oscillators with a spin index taking values in a Lie algebra representation as well as matrix indices for the adjoint representation of U(N). We show that SMT describes N=4 super-Yang-Mills theory (SYM) near zero-temperature critical points in the grand canonical phase diagram. Equivalently, SMT arises from non-relativistic limits of N=4 SYM. Even though SMT is a non-relativistic quantum mechanical theory it contains a variety of phases mimicking the AdS/CFT correspondence. Moreover, the infinite g limit of SMT can be mapped to the supersymmetric sector of string theory on AdS_5 x S^5. We study SU(2) SMT in detail. At large N and low temperatures it is a theory of spin chains that for small g resembles planar gauge theory and for large g a non-relativistic string theory. When raising the temperature a partial deconfinement transit...

Harmark, Troels

2014-01-01T23:59:59.000Z

145

Visualization and dimensional scaling for some three-body problems in atomic and molecular quantum mechanics  

SciTech Connect (OSTI)

Three-body problems in atomic and molecular quantum mechanics, comprising one electron-two nuclei and two electron-one nucleus, are studied from their Schroedinger-Born-Oppenheimer models. The following are main topics of interest in this paper: (1) review of foundational mathematical properties of the multiparticle Schroedinger operator, (2) visualization of H{sub 2}{sup +} (hydrogen molecular ion)-like and He (helium)-like molecular and atomic states, and (3) spectrum of He obtained by the large-dimension scaling limit. The authors begin with topic (1) for the tutorial purpose and devote topics (2) and (3) to new contributions of the analytical, numerical, and visualization nature. Relevant heuristics, graphics, proofs, and calculations are presented.

Chen Goong [Department of Mathematics and Institute for Quantum Studies, Texas A and M University, College Station, Texas 77843 (United States); Ding Zhonghai [Department of Mathematical Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada 89154-4020 (United States); Perronnet, Alain [Laboratoire J.-L. Lions, Universite Pierre et Marie Curie, Paris Cedex 05 (France); Zhang Zhigang [Department of Mathematics, University of Houston, Houston, Texas 77004 (United States)

2008-06-15T23:59:59.000Z

146

Controlling the dynamics of quantum mechanical systems sustaining dipole-forbidden transitions via optical nanoantennas  

Science Journals Connector (OSTI)

We suggest to excite dipole-forbidden transitions in quantum mechanical systems by using appropriately designed optical nanoantennas. The antennas are tailored such that their near field contains sufficiently strong contributions of higher-order multipole moments. The strengths of these moments exceed their free-space analogs by several orders of magnitude. The impact of such excitation enhancement is exemplarily investigated by studying the dynamics of a three-level system. It decays upon excitation by an electric quadrupole transition via two electric dipole transitions. Since one dipole transition is assumed to be radiative, the enhancement of this emission serves as a figure of merit. Such self-consistent treatment of excitation, emission, and internal dynamics as developed in this contribution is the key to predict any observable quantity. The suggested scheme may represent a blueprint for future experiments and will find many obvious spectroscopic and sensing applications.

Robert Filter; Stefan Mhlig; Toni Eichelkraut; Carsten Rockstuhl; Falk Lederer

2012-07-05T23:59:59.000Z

147

A quantitative quantum-chemical analysis tool for the distribution of mechanical force in molecules  

SciTech Connect (OSTI)

The promising field of mechanochemistry suffers from a general lack of understanding of the distribution and propagation of force in a stretched molecule, which limits its applicability up to the present day. In this article, we introduce the JEDI (Judgement of Energy DIstribution) analysis, which is the first quantum chemical method that provides a quantitative understanding of the distribution of mechanical stress energy among all degrees of freedom in a molecule. The method is carried out on the basis of static or dynamic calculations under the influence of an external force and makes use of a Hessian matrix in redundant internal coordinates (bond lengths, bond angles, and dihedral angles), so that all relevant degrees of freedom of a molecule are included and mechanochemical processes can be interpreted in a chemically intuitive way. The JEDI method is characterized by its modest computational effort, with the calculation of the Hessian being the rate-determining step, and delivers, except for the harmonic approximation, exact ab initio results. We apply the JEDI analysis to several example molecules in both static quantum chemical calculations and Born-Oppenheimer Molecular Dynamics simulations in which molecules are subject to an external force, thus studying not only the distribution and the propagation of strain in mechanically deformed systems, but also gaining valuable insights into the mechanochemically induced isomerization of trans-3,4-dimethylcyclobutene to trans,trans-2,4-hexadiene. The JEDI analysis can potentially be used in the discussion of sonochemical reactions, molecular motors, mechanophores, and photoswitches as well as in the development of molecular force probes.

Stauch, Tim; Dreuw, Andreas, E-mail: dreuw@uni-heidelberg.de [Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg (Germany)] [Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg (Germany)

2014-04-07T23:59:59.000Z

148

Proton diffusion pathways and rates in Y-doped BaZrO3 solid oxide electrolyte from quantum mechanics  

E-Print Network [OSTI]

solid oxide fuel cells based on yttria-stabilized zirconia. In addition, doped perovskite oxides oftenProton diffusion pathways and rates in Y-doped BaZrO3 solid oxide electrolyte from quantum solid oxide proton conductors the principal fea- tures of the proton transport mechanism are generally

Goddard III, William A.

149

Calculation of the electron two-slit experiment using a quantum mechanical variational principle  

E-Print Network [OSTI]

A nonlocal relativistic variational principle (VP) has recently been proposed as an alternative to the Dirac wave equation of standard quantum mechanics. We apply that principle to the electron two-slit experiment. The detection system is modelled as a screen made of atoms, any one of which can be excited by the incident electron, but we avoid restricting the detection mechanism further. The VP is shown to predict that, at the time the electron reaches the screen, its wavefunction will be localized to the neighborhood of a single atom, resulting in a position-type measurement. In an ensemble of such experiments ("identically prepared" except that the initial phase of the wavefunction--the hidden variable in the VP formulation--is sampled over the expected uniform distribution), the distribution of measured positions will reproduce the interference pattern predicted by the Dirac equation. We also demonstrate that with a detection system designed fundamentally to detect the electron's transverse wavelength rather than its position, the VP predicts that one such mode will be detected, that is, a wavelength measurement will result. Finally, it is shown that these results are unchanged in the "delayed choice" variant of the experiment.

Alan K. Harrison

2012-08-02T23:59:59.000Z

150

Session #1: Cutting Edge Methodologies--Beyond Current DFT  

Broader source: Energy.gov [DOE]

Benchmarking state-of-the-art approaches, accurate energy landscape. Identify problems with the current DFT-LDA and GGA approaches and possible pathways to overcome these problems.

151

Mechanical Behaviors of Alloys From First Principles  

E-Print Network [OSTI]

Some Backgrounds on The Quantum Mechanical Stresses . . .3.2.2 The Quantum Mechanical Stresses and The Generalized3.2.3 Quantum-Mechanical

Hanlumyuang, Yuranan

2011-01-01T23:59:59.000Z

152

Interaction of the cesium cation with calix[4]arene-bis(t-octylbenzo-18-crown-6): Extraction and DFT study  

Science Journals Connector (OSTI)

From extraction experiments and ?-activity measurements, the extraction constant corresponding to the equilibrium Cs+ (aq)+I? (aq)+1 (org)?1?Cs+ (org)+I? (org) taking place in the two-phase water-phenyltrifluoromethyl sulfone (abbrev. FS 13) system (1=calix[4]arene-bis(t-octylbenzo-18-crown-6); aq=aqueous phase, org=FS 13 phase) was evaluated as logKex(1?Cs+,I?)=2.10.1. Further, the stability constant of the 1?Cs+ complex in FS 13 saturated with water was calculated for a temperature of 25C: log?org(1?Cs+)=9.90.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1?Cs+ was derived. In the resulting 1?Cs+ complex, the central cation Cs+ is bound by eight bond interactions to six oxygen atoms of the respective 18-crown-6 moiety and to two carbons of the corresponding two benzene rings of the parent ligand 1 via cation? interaction.

Emanuel Makrlk; Petr Toman; Petr Va?ura; Bruce A. Moyer

2013-01-01T23:59:59.000Z

153

Erasing the traces of classical mechanics in ionization of H{sub 2} by quantum interferences  

SciTech Connect (OSTI)

The single ionization of hydrogen molecules by fast electron impact is studied theoretically for transitions from the ground (gerade) state to final ground (gerade) and first-excited (ungerade) states of H{sub 2}{sup +}. It is shown that under definite conditions and for particular orientations of the molecule, the main physical features of the ionization reaction, which are the binary and recoil peaks usually associated with classical mechanisms, are completely erased by quantum interference effects that resemble the ones predicted previously for photoionization reactions. However, these new effects cannot be derived from photoionization results, as the electromagnetic field cannot transfer momentum. In addition, it is found that the emission spectra of transitions leading to the final gerade and ungerade states of the H{sub 2}{sup +} residual target are analogous in certain cases to the patterns of two sources emitting waves in phase or antiphase, respectively. Finally, we show how an average of the emission from randomly oriented molecules produces a binary peak at the classical expected position, in agreement with experiments.

Fojon, O. A.; Stia, C. R.; Rivarola, R. D. [Laboratorio de Colisiones Atomicas and Instituto de Fisica Rosario, CONICET-UNR, Avenida Pellegrini 250, 2000 Rosario (Argentina)

2011-09-15T23:59:59.000Z

154

Quantum dynamics of two-optical modes and a single mechanical mode optomechanical system: selective energy exchange  

E-Print Network [OSTI]

We study the quantum dynamics of an optomechanical setup comprising two optical modes and one mechanical mode. We show that the same system can undergo a Dicke-Hepp-Lieb superradiant type phase transition. We found that the coupling between the momentum quadratures of the two optical fields give rise to a new critical point. We show that selective energy exchange between any two modes is possible by coherent control of the coupling parameters. In addition we also demonstrate the occurrence of Normal Mode Splitting (NMS) in the mechanical displacement spectrum.

Neha Aggarwal; Aranya B Bhattacherjee

2013-02-06T23:59:59.000Z

155

Session #1: Cutting Edge Methodologies--Beyond Current DFT  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Session #1: Cutting Edge Methodologies (beyond Current DFT) Moderator: Shengbai Zhang (RPI/ REL) Topics to be addressed: Benchmarking state-of-the-art approaches, accurate energy landscape. Identify problems with the current DFT-LDA and GGA approaches and possible pathways to overcome these problems. PBE PBE How Bad is DFT for vdW Interactions? fcc Ar Benzene dimer PBE LDA Exp CCSD(T) LDA PBE vdW Interaction between H 2 and Carbon � PBE Graphene CCSD(T) LDA Benzene omitted in the LDA and GGA van der Walls (vdW)-DFT: Langreth, Kohn � Fully nonlocal � functional: � � Long-range nonlocal correlation energy functional (omitted in the LDA and GGA) ) ( � Computational cost considerably more than GGA � Added as post-GGA energy correction but force

156

Session #1: Cutting Edge Methodologies--Beyond Current DFT  

Broader source: Energy.gov (indexed) [DOE]

dimer PBE LDA Exp CCSD(T) LDA PBE vdW Interaction between H 2 and Carbon PBE Graphene CCSD(T) LDA Benzene omitted in the LDA and GGA van der Walls (vdW)-DFT: Langreth,...

157

Quantum discord  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Quantum discord Quantum discord 1663 Los Alamos science and technology magazine Latest Issue:November 2013 All Issues » submit Quantum discord A distinguishing aspect of quantum mechanics discovered at Los Alamos that may be critical to building a quantum computer March 25, 2013 Spinning coins turning into binary numbers Quantum computing Quantum computing can be carried out without the delicate entanglement of qubits previously believed to be necessary Quantum computing, in which quantum bits of information (or qubits) juggle a "superposition" of multiple values simultaneously, offers to unleash tremendous computational power if the qubits can be effectively isolated to prevent decoherence: information describing quantum states dispersing into the environment. But recent research has shown that quantum computing can be carried out

158

Quantum Simulation  

E-Print Network [OSTI]

Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry and cosmology. Quantum simulation could be implemented using quantum computers, but also with simpler, analog devices that would require less control, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar molecules, electrons in semiconductors, superconducting circuits, nuclear spins and photons have been proposed as quantum simulators. This review outlines the main theoretical and experimental aspects of quantum simulation and emphasizes some of the challenges and promises of this fast-growing field.

I. M. Georgescu; S. Ashhab; Franco Nori

2014-03-13T23:59:59.000Z

159

Propagation of uncertainties in the nuclear DFT models  

E-Print Network [OSTI]

Parameters of the nuclear density functional theory (DFT) models are usually adjusted to experimental data. As a result they carry certain theoretical error, which, as a consequence, carries out to the predicted quantities. In this work we address the propagation of theoretical error, within the nuclear DFT models, from the model parameters to the predicted observables. In particularly, the focus is set on the Skyrme energy density functional models.

Markus Kortelainen

2014-09-04T23:59:59.000Z

160

Properties of few-body systems in relativistic quantum mechanics and constraints from transformations under Poincar space-time translations  

E-Print Network [OSTI]

Different approaches have been applied to the calculation of form factors of various hadronic systems within relativistic quantum mechanics. In a one-body current approximation, they can lead to results evidencing large discrepancies. Looking for an explanation of this spreading, it is shown that, for the largest part, these discrepancies can be related to a violation of Poincar\\'e space-time translation invariance. Beyond energy-momentum conservation, which is generally assumed, fulfilling this symmetry implies specific relations that are generally ignored. Their relevance within the present context is discussed in detail both to explain the differences between predictions and to remove them.

B. Desplanques

2006-11-17T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

GRADUATE QUANTUM MECHANICS: 502 Spring 2002 Assignment 5: due Mon April 8th.  

E-Print Network [OSTI]

is the ground-state energy? What is the Fermi energy? (b) What are the ground-state and Fermi energies if we the properties of your environment depend on the Pauli Exclusion principle. In each case, describe how the world statistics considerations, obtain restrictions on the magnetic quantum numbers corresponding to Jz. 1 #12;

Coleman, Piers

162

Advances in Quantum Chemistry, 43, 95-117 (2003) Differentiability in density-functional theory  

E-Print Network [OSTI]

Advances in Quantum Chemistry, 43, 95-117 (2003) Differentiability in density-functional theory in density-functional theory (DFT) is investigated, and it is shown that the so-called Levy- Lieb functional The differentiability of density functionals is of fundamental importance in Density-Functional Theory (DFT) and forms

Lindgren, Ingvar

163

Controlling the transport of an ion: Classical and quantum mechanical solutions  

E-Print Network [OSTI]

We investigate the performance of different control techniques for ion transport in state-of-the-art segmented miniaturized ion traps. We employ numerical optimization of classical trajectories and quantum wavepacket propagation as well as analytical solutions derived from invariant based inverse engineering and geometric optimal control. We find that accurate shuttling can be performed with operation times below the trap oscillation period. The maximum speed is limited by the maximum acceleration that can be exerted on the ion. When using controls obtained from classical dynamics for wavepacket propagation, wavepacket squeezing is the only quantum effect that comes into play for a large range of trapping parameters. We show that this can be corrected by a compensating force derived from invariant based inverse engineering, without a significant increase in the operation time.

H. A. Frst; M. H. Goerz; U. G. Poschinger; M. Murphy; S. Montangero; T. Calarco; F. Schmidt-Kaler; K. Singer; C. P. Koch

2013-12-15T23:59:59.000Z

164

Mechanism of terahertz photoconductivity in semimetallic HgTe/CdHgTe quantum wells  

SciTech Connect (OSTI)

Terahertz photoconductivity in magnetic fields in semimetallic HgTe/CdHgTe quantum wells has been studied. The main contribution to photoconductivity comes from a signal that appears as a result of electron-gas heating. It is shown that, with the cyclotron resonance conditions satisfied, the photoconductivity signal is composed of cyclotron-resonance and bolometric components. However, in this case too, the bolometric contribution predominates.

Vasilyev, Yu. B., E-mail: yu.vasilyev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Mikhailov, N. N. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Gouider, F. [Institut fuer Angewandte Physik (Germany); Vasilyeva, G. Yu. [St. Petersburg State Polytechnic University (Russian Federation); Nachtwei, G. [Institut fuer Angewandte Physik (Germany)

2012-05-15T23:59:59.000Z

165

Modeling Excited States in TiO2 Nanoparticles: On the Accuracy of a TD-DFT Based Description  

SciTech Connect (OSTI)

We have investigated the suitability of Time-Dependent Density Functional Theory (TD-DFT) to describe vertical low-energy excitations in naked and hydrated titanium dioxide nanoparticles through a comparison with results from Equation-of-Motion Coupled Cluster (EOM-CC) quantum chemistry methods. We demonstrate that for most TiO2 nanoparticles TD-DFT calculations with commonly used exchange-correlation (XC-)potentials (e.g. B3LYP) and EOM-CC methods give qualitatively similar results. Importantly, however, we also show that for an important subset of structures, TD-DFT gives qualitatively different results depending upon the XC-potential used and that in this case only TD-CAM-B3LYP and TD-BHLYP calculations yield results that are consistent with those obtained using EOM-CC theory. Moreover, we demonstrate that the discrepancies for such structures arise from a particular combination of defects, excitations involving which are charge-transfer excitations and hence are poorly described by XC-potentials that contain no or low fractions of Hartree-Fock like exchange. Finally, we discuss that such defects are readily healed in the presence of ubiquitously present water and that as a result the description of vertical low-energy excitations for hydrated TiO2 nanoparticles is hence non-problematic.

Berardo, Enrico; Hu, Hanshi; Shevlin, S. A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

2014-03-11T23:59:59.000Z

166

The Conventionality of Synchronization and the Causal Structure of Quantum Mechanics  

E-Print Network [OSTI]

Measuring velocities requires the synchronization of spatially-separated clocks. Because this synchronization must precede the determination of velocities, no system of clock synchronization--such as that based on Einstein's presumption of light-speed isotropy--can ever be founded on an experimentally-validated velocity. I argue that this very old observation, which lingers in the philosophical literature under the heading ``Conventionality of Synchronization,'' suggests an explanation of why ``spooky'' quantum correlations can transfer no information at any speed, superluminal or otherwise. This work constitutes the first application of the Conventionality doctrine outside of Relativity itself.

James Carrubba

2006-06-28T23:59:59.000Z

167

Comment on [open quotes]Nonlocality, counterfactuals, and quantum mechanics[close quotes  

SciTech Connect (OSTI)

A recent proof [H. P. Stapp, Am. J. Phys. [bold 65], 300 (1997)], formulated in the symbolic language of modal logic, claims to show that contemporary quantum theory, viewed as a set of rules that allow us to calculate statistical predictions among certain kinds of observations, cannot be imbedded in any rational framework that conforms to the principles that (1) the experimenters[close quote] choices of which experiments they will perform can be considered to be free choices, (2) outcomes of measurements are unique, and (3) the free choices just mentioned have no backward-in-time effects of any kind. This claim is similar to Bell[close quote]s theorem, but much stronger, because no reality assumption alien to quantum philosophy is used. The paper being commented on [W. Unruh, Phys. Rev. A [bold 59], 126 (1999)] argues that some such reality assumption has been [open quotes]smuggled[close quotes] in. That argument is examined here and shown, I believe, to be defective. [copyright] [ital 1999] [ital The American Physical Society

Stapp, H.P. (Lawrence Berkeley National Laboratory, University of California at Berkely, Berkeley, California 94720 (United States))

1999-09-01T23:59:59.000Z

168

Analyzing carrier escape mechanisms in InAs/GaAs quantum dot p-i-n junction photovoltaic cells  

Science Journals Connector (OSTI)

Intermediate band solar cells (IBSCs) are third-generation photovoltaic (PV) devices that can harvest sub-bandgap photons normally not absorbed in a single-junction solar cell. Despite the large increase in total solar energy conversion efficiency predicted for IBSC devices substantial challenges remain to realizing these efficiency gains in practical devices. We evaluate carrier escape mechanisms in an InAs/GaAs quantum dot intermediate band p-i-n junction PV device using photocurrent measurements under sub-bandgap illumination. We show that sub-bandgap photons generate photocurrent through a two-photon absorption process but that carrier trapping and retrapping limit the overall photocurrent. The results identify a key obstacle that must be overcome in order to realize intermediate band devices that outperform single junction photovoltaic cells.

S. Polly; S. M. Hubbard; M. F. Doty

2014-01-01T23:59:59.000Z

169

Small-energy series for one-dimensional quantum-mechanical models with non-symmetric potentials  

E-Print Network [OSTI]

We generalize a recently proposed small-energy expansion for one-dimensional quantum-mechanical models. The original approach was devised to treat symmetric potentials and here we show how to extend it to non-symmetric ones. Present approach is based on matching the logarithmic derivatives for the left and right solutions to the Schr\\"odinger equation at the origin (or any other point chosen conveniently) . As in the original method, each logarithmic derivative can be expanded in a small-energy series by straightforward perturbation theory. We test the new approach on four simple models, one of which is not exactly solvable. The perturbation expansion converges in all the illustrative examples so that one obtains the ground-state energy with an accuracy determined by the number of available perturbation corrections.

Paolo Amore; Francisco M. Fernndez

2014-10-21T23:59:59.000Z

170

A quantum mechanical relation connecting time, temperature, and cosmological constant of the universe: Gamow's relation revisited as a special case  

E-Print Network [OSTI]

Considering our expanding universe as made up of gravitationally interacting particles which describe particles of luminous matter and dark matter and dark energy which is described by a repulsive harmonic potential among the points in the flat 3-space, we derive a quantum mechanical relation connecting, temperature of the cosmic microwave background radiation, age, and cosmological constant of the universe. When the cosmological constant is zero, we get back the Gamow's relation with a much better coefficient. Otherwise, our theory predicts a value of the cosmological constant $2.234 10^{-56} {\\rm {cm^{-2}}}$ when the present values of cosmic microwave background temperature of 2.728 K and age of the universe 14 billion years are taken as input.

Mishra, S

2007-01-01T23:59:59.000Z

171

Beyond quantum mechanics? Hunting the 'impossible' atoms (Pauli Exclusion Principle violation and spontaneous collapse of the wave function at test)  

E-Print Network [OSTI]

The development of mathematically complete and consistent models solving the so-called "measurement problem", strongly renewed the interest of the scientific community for the foundations of quantum mechanics, among these the Dynamical Reduction Models posses the unique characteristic to be experimentally testable. In the first part of the paper an upper limit on the reduction rate parameter of such models will be obtained, based on the analysis of the X-ray spectrum emitted by an isolated slab of germanium and measured by the IGEX experiment. The second part of the paper is devoted to present the results of the VIP (Violation of the Pauli exclusion principle) experiment and to describe its recent upgrade. The VIP experiment established a limit on the probability that the Pauli Exclusion Principle (PEP) is violated by electrons, using the very clean method of searching for PEP forbidden atomic transitions in copper.

Piscicchia, K; Bartalucci, S; Bassi, A; Bertolucci, S; Berucci, C; Bragadireanu, A M; Cargnelli, M; Clozza, A; De Paolis, L; Di Matteo, S; Donadi, S; d'Uffizi, A; Egger, J-P; Guaraldo, C; Iliescu, M; Ishiwatari, T; Laubenstein, M; Marton, J; Milotti, E; Pietreanu, D; Ponta, T; Sbardella, E; Scordo, A; Shi, H; Sirghi, D L; Sirghi, F; Sperandio, L; Doce, O Vazquez; Zmeskal, J

2015-01-01T23:59:59.000Z

172

6.728 Applied Quantum and Statistical Physics, Fall 2002  

E-Print Network [OSTI]

Elementary quantum mechanics and statistical physics. Introduces applied quantum physics. Emphasizes experimental basis for quantum mechanics. Applies Schrodinger's equation to the free particle, tunneling, the harmonic ...

Bulovic, Vladimir, 1970-

173

Screening effects on field emission from arrays of (5,5) carbon nanotubes: Quantum mechanical simulations  

Science Journals Connector (OSTI)

The simulation of field electron emission from arrays of micrometer-long open-ended (5,5) carbon nanotubes is performed in the framework of quantum theory of many electrons. It is found that the applied external field is strongly screened when the spacing distance is shorter than the length of the carbon nanotubes. The optimal spacing distance is two to three times of the nanotube length, slightly depending on the applied external fields. The electric screening can be described by a factor that is an exponential function of the ratio of the spacing distance to the length of the carbon nanotubes. For a given length, the field enhancement factor decreases sharply as the screening factor is larger than 0.05. The simulation implies that the thickness of the array should be larger than a value, but it does not help the emission much by increasing the thickness a great deal.

Guihua Chen; Weiliang Wang; Jie Peng; Chunshan He; Shaozhi Deng; Ningsheng Xu; Zhibing Li

2007-11-13T23:59:59.000Z

174

Coupling constant metamorphosis and Nth order symmetries in classical and quantum mechanics  

E-Print Network [OSTI]

We review the fundamentals of coupling constant metamorphosis (CCM) and the St\\"ackel transform, and apply them to map integrable and superintegrable systems of all orders into other such systems on different manifolds. In general, CCM does not preserve the order of constants of the motion or even take polynomials in the momenta to polynomials in the momenta. We study specializations of these actions which do preserve polynomials and also the structure of the symmetry algebras in both the classical and quantum cases. We give several examples of non-constant curvature 3rd and 4th order superintegrable systems in 2 space dimensions obtained via CCM, with some details on the structure of the symmetry algebras preserved by the transform action.

E. G. Kalnins; W. Miller Jr.; S. Post

2009-08-31T23:59:59.000Z

175

Applied quantum mechanics 1 Applied Quantum Mechanics  

E-Print Network [OSTI]

t an t n e int­ n = . If an t can be expressed as a power series in the perturbing potential then W^ x) A particle of mass m0 is initially in the ground state of a one dimensional har- monic oscillator. At time limit, t . Problem 8.2 An electron is in the ground state of a one-dimensional rectangular potential

Levi, Anthony F. J.

176

Applied quantum mechanics 1 Applied Quantum Mechanics  

E-Print Network [OSTI]

that describe the time-dependent state . If can be expressed as a power series in the perturbing potential of a one dimensional har- monic oscillator. At time t = 0 a perturbation is applied where V0-dimensional rectangular potential well for which in the range and elsewhere. It is decided to control the state

Levi, Anthony F. J.

177

Applied quantum mechanics 1 Applied Quantum Mechanics  

E-Print Network [OSTI]

-dimensional har- monic potential and is subject to an oscillating electric field . (a) Write down the Hamiltonian oscillator potential in terms of momentum and position . (b) If one defines new operators show of mass m in a one-dimensional harmonic oscillator potential. (b) Find the value of the product

Levi, Anthony F. J.

178

Analyzing Data Streams by Online DFT Alexander Hinneburg1  

E-Print Network [OSTI]

University of Technology, Germany dirk.habich@tu-dresden.de 3 Technical University of Ilmenau, Germany marcel Martin-Luther University of Halle-Wittenberg, Germany hinneburg@informatik.uni-halle.de 2 Dresden DFT lead to a number of interesting applications, e.g., forecasting, clean- ing, and moni

Hinneburg, Alexander

179

Electronic Spectra and DFT Calculations of Hexanuclear Chalcocyanide Rhenium Clusters  

Science Journals Connector (OSTI)

Electronic Spectra and DFT Calculations of Hexanuclear Chalcocyanide Rhenium Clusters ... The good agreement with experiment obtained for the geometrical parameters gives the basis for comparing the calculated electronic transitions of these complexes with the experimental electronic spectra. ... On the calculation of bonding energies by the Hartree Fock Slater method. ...

S. G. Kozlova; S. P. Gabuda; K. A. Brylev; Yu. V. Mironov; V. E. Fedorov

2004-11-03T23:59:59.000Z

180

Origin of the improved photo-catalytic activity of F-doped ZnWO{sub 4}: A quantum mechanical study  

SciTech Connect (OSTI)

Two different mechanisms for improving photo-catalytic activity in different types of F-doped ZnWO{sub 4} are tentatively proposed, based on density function theory calculations. When the lattice O atom is substituted by one F atom, our calculations show that a reduced W{sup 5+} center adjacent to the doped F atom will act as a trap for the photo-induced electron, and will thus result in a reduction of electron-hole recombination and improvement of the photo-catalytic activity. For the interstitial F-doped model, partial F 2p states mixing with O 2p states localize above the top of the valence band and act as the frontier orbital level. Electronic transitions from these localized states induce a red shift of about 54 nm of the optical absorption edge. This work shows that F-doped ZnWO{sub 4} will be a promising photo-catalyst with favorable photo-catalytic activity in the UV region. -- Graphical Abstract: DFT calculations are used to investigate the origin of the improved photo-activity of monoclinic ZnWO{sub 4} induced by the substituted and interstitial F-doping. Two possible mechanisms are tentatively put forward according to the F-doping types. Display Omitted

Sun, Honggang [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Fan, Weiliu, E-mail: fwl@sdu.edu.c [Department of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Li, Yanlu; Cheng, Xiufeng; Li, Pan [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Zhao, Xian, E-mail: zhaoxian@icm.sdu.edu.c [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

2010-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Quantum discord is Bohrs notion of non-mechanical disturbance introduced to counter the EinsteinPodolskyRosen argument  

SciTech Connect (OSTI)

By rigorously formalizing the EinsteinPodolskyRosen (EPR) argument, and Bohrs reply, one can appreciate that both arguments were technically correct. Their opposed conclusions about the completeness of quantum mechanics hinged upon an explicit difference in their criteria for when a measurement on Alices system can be regarded as not disturbing Bobs system. The EPR criteria allow their conclusionincompletenessto be reached by establishing the physical reality of just a single observable q (not of both q and its conjugate observable p), but I show that Bohrs definition of disturbance prevents the EPR chain of reasoning from establishing even this. Moreover, I show that Bohrs definition is intimately related to the asymmetric concept of quantum discord from quantum information theory: if and only if the joint state has no Alice-discord, she can measure any observable without disturbing (in Bohrs sense) Bobs system. Discord can be present even when systems are unentangled, and this has implications for our understanding of the historical development of notions of quantum nonlocality. -- Highlights: Both the EPR argument, and Bohrs reply, were technically correct. Their opposed conclusions came from different criteria for disturbance. Bohrs criterion works against even the simplified (one-variable) EPR argument. Bohrs criterion for disturbance is intimately related to quantum discord. This illuminates the historical development of notions of quantum nonlocality.

Wiseman, Howard M., E-mail: H.Wiseman@Griffith.edu.au

2013-11-15T23:59:59.000Z

182

Asymptotic Freedom, Dimensional Transmutation, and an Infra-red Conformal Fixed Point for the $?$-Function Potential in 1-dimensional Relativistic Quantum Mechanics  

E-Print Network [OSTI]

We consider the Schr\\"odinger equation for a relativistic point particle in an external 1-dimensional $\\delta$-function potential. Using dimensional regularization, we investigate both bound and scattering states, and we obtain results that are consistent with the abstract mathematical theory of self-adjoint extensions of the pseudo-differential operator $H = \\sqrt{p^2 + m^2}$. Interestingly, this relatively simple system is asymptotically free. In the massless limit, it undergoes dimensional transmutation and it possesses an infra-red conformal fixed point. Thus it can be used to illustrate non-trivial concepts of quantum field theory in the simpler framework of relativistic quantum mechanics.

M. H. Al-Hashimi; A. M. Shalaby; U. -J. Wiese

2014-04-11T23:59:59.000Z

183

Quantum Thermodynamic Cycles and Quantum Heat Engines (II)  

E-Print Network [OSTI]

We study the quantum mechanical generalization of force or pressure, and then we extend the classical thermodynamic isobaric process to quantum mechanical systems. Based on these efforts, we are able to study the quantum version of thermodynamic cycles that consist of quantum isobaric process, such as quantum Brayton cycle and quantum Diesel cycle. We also consider the implementation of quantum Brayton cycle and quantum Diesel cycle with some model systems, such as single particle in 1D box and single-mode radiation field in a cavity. These studies lay the microscopic (quantum mechanical) foundation for Szilard-Zurek single molecule engine.

Quan, H T

2008-01-01T23:59:59.000Z

184

The quantum correlation between the selection of the problem and that of the solution sheds light on the mechanism of the quantum speed up  

E-Print Network [OSTI]

In classical problem solving, there is of course correlation between the selection of the problem on the part of Bob (the problem setter) and that of the solution on the part of Alice (the problem solver). In quantum problem solving, this correlation becomes quantum. This means that Alice contributes to selecting 50% of the information that specifies the problem. As the solution is a function of the problem, this gives to Alice advanced knowledge of 50% of the information that specifies the solution. Both the quadratic and exponential speed ups are explained by the fact that quantum algorithms start from this advanced knowledge.

Giuseppe Castagnoli

2010-05-10T23:59:59.000Z

185

Quantum correlation between the selection of the problem and that of the solution sheds light on the mechanism of the quantum speed-up  

SciTech Connect (OSTI)

In classical problem solving, there is, of course, correlation between the selection of the problem on the part of Bob (the problem setter) and that of the solution on the part of Alice (the problem solver). In quantum problem solving, this correlation becomes quantum. This means that Alice contributes to selecting 50% of the information that specifies the problem. As the solution is a function of the problem, this gives to Alice advanced knowledge of 50% of the information that specifies the solution. Both the quadratic and exponential speed-ups are explained by the fact that quantum algorithms start from this advanced knowledge.

Castagnoli, Giuseppe [Via San Bernardo 9/A, I-16030 Pieve Ligure (Genova) (Italy)

2010-11-15T23:59:59.000Z

186

Sandia National Laboratories: Quantum Systems  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Quantum Systems Sensors Sandia leverages quantum mechanics to enable exquisite metrology devices, such as inertial sensors and frequency standards that go beyond the capabilities...

187

Copenhagen Quantum Mechanics Emerges from a Deterministic Schroedinger Theory in 11 Dimensional Spacetime Including Weak Field Gravitation  

E-Print Network [OSTI]

We construct a world model consisting of a matter field living in 4 dimensional spacetime and a gravitational field living in 11 dimensional spacetime. The seven hidden dimensions are compactified within a radius estimated by reproducing the particle - wave characteristic of diffraction experiments. In the presence of matter fields the gravitational field develops localized modes with elementary excitations called gravonons which are induced by the sources (massive particles). The final world model treated here contains only gravonons and a scalar matter field. The solution of the Schroedinger equation for the world model yields matter fields which are localized in the 4 dimensional subspace. The localization has the following properties: (i) There is a chooser mechanism for the selection of the localization site. (ii) The chooser selects one site on the basis of minor energy differences and differences in the gravonon structure between the sites, which appear statistical. (iii) The changes from one localization site to a neighbouring one take place in a telegraph-signal like manner. (iv) The times at which telegraph like jumps occur dependent on subtleties of the gravonon structure which appear statistical. (v) The fact that the dynamical law acts in the configuration space of fields living in 11 dimensional spacetime lets the events observed in 4 dimensional spacetime appear non-local. In this way the phenomenology of Copenhagen quantum mechanics is obtained without the need of introducing the process of collapse and a probabilistic interpretation of the wave function. Operators defining observables need not be introduced. All experimental findings are explained in a deterministic way as a consequence of the time development of the wave function in configuration space according to Schroedinger's equation.

Gerold Doyen; Deiana Drakova

2014-08-12T23:59:59.000Z

188

Cluster-continuum quantum mechanical models to guide the choice of anions for Li{sup +}-conducting ionomers  

SciTech Connect (OSTI)

A quantum-mechanical investigation on Li poly(ethylene oxide)-based ionomers was performed in the cluster-continuum solvation model (CCM) that includes specific solvation in the first shell surrounding the cation, all surrounded by a polarizable continuum. A four-state model, including a free Li cation, Li{sup +}-anion pair, triple ion, and quadrupole was used to represent the states of Li{sup +} within the ionomer in the CCM. The relative energy of each state was calculated for Li{sup +} with various anions, with dimethyl ether representing the ether oxygen solvation. The population distribution of Li{sup +} ions among states was estimated by applying Boltzmann statistics to the CCM energies. Entropy difference estimates are needed for populations to better match the true ionomer system. The total entropy change is considered to consist of four contributions: translational, rotational, electrostatic, and solvent immobilization entropies. The population of ion states is reported as a function of Bjerrum length divided by ion-pair separation with/without entropy considered to investigate the transition between states. Predicted concentrations of Li{sup +}-conducting states (free Li{sup +} and positive triple ions) are compared among a series of anions to indicate favorable features for design of an optimal Li{sup +}-conducting ionomer; the perfluorotetraphenylborate anion maximizes the conducting positive triple ion population among the series of anions considered.

Shiau, Huai-Suen; Janik, Michael J. [Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Liu, Wenjuan; Colby, Ralph H. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2013-11-28T23:59:59.000Z

189

Quantum Dating Market  

E-Print Network [OSTI]

We consider the dating market decision problem under the quantum mechanics point of view. Quantum states whose associated amplitudes are modified by men strategies are used to represent women. Grover quantum search algorithm is used as a playing strategy. Success is more frequently obtained by playing quantum than playing classic.

O. G. Zabaleta; C. M. Arizmendi

2010-03-04T23:59:59.000Z

190

E-Print Network 3.0 - approximate dft method Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

D'Alberto Yahoo pdalbert@yahoo-inc.com Peter A... - tions of the discrete Fourier transform (DFT) in fixed point precision. The partitioning strategy Source: Moura, Jos -...

191

Optical quantum memory  

E-Print Network [OSTI]

Quantum memory is important to quantum information processing in many ways: a synchronization device to match various processes within a quantum computer, an identity quantum gate that leaves any state unchanged, and a tool to convert heralded photons to photons-on-demand. In addition to quantum computing, quantum memory would be instrumental for the implementation of long-distance quantum communication using quantum repeaters. The importance of this basic quantum gate is exemplified by the multitude of optical quantum memory mechanisms being studied: optical delay lines, cavities, electromagnetically-induced transparency, photon-echo, and off-resonant Faraday interaction. Here we report on the state-of-the-art in the field of optical quantum memory, including criteria for successful quantum memory and current performance levels.

A. I. Lvovsky; B. C. Sanders; W. Tittel

2010-02-24T23:59:59.000Z

192

Adsorption of silver dimer on graphene - A DFT study  

SciTech Connect (OSTI)

We performed a systematic density functional theory (DFT) study of the adsorption of silver dimer (Ag{sub 2}) on graphene using SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Ag2-graphene system are calculated. The minimum energy configuration for a silver dimer is parallel to the graphene sheet with its two atoms directly above the centre of carbon-carbon bond. The negligible charge transfer between the dimer and the surface is also indicative of a weak bond. The methodology demonstrated in this paper may be applied to larger silver clusters on graphene sheet.

Kaur, Gagandeep, E-mail: gaganj1981@yahoo.com [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and Chandigarh Engineering College, Landran, Mohali-140307, Punjab (India); Gupta, Shuchi [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and University Institute of Engineering and Technology, Panjab University, Chandigarh -160014 (India); Rani, Pooja; Dharamvir, Keya [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014 (India)

2014-04-24T23:59:59.000Z

193

Role of exchange in density-functional theory for weakly interacting systems: Quantum Monte Carlo analysis of electron density and interaction energy  

E-Print Network [OSTI]

We analyze the density-functional theory (DFT) description of weak interactions by employing diffusion and reptation quantum Monte Carlo (QMC) calculations, for a set of benzene-molecule complexes. While the binding energies ...

Grossman, Jeffrey C.

194

Reply to the comment of Y. Aharonov and L. Vaidman on ``Time asymmetry in quantum mechanics: a retrodiction paradox''  

E-Print Network [OSTI]

In the standard physical interpretation of quantum theory, prediction and retrodiction are not symmetric. The opposite assertion by some authors results from their use of non-standard interpretations of the theory.

Asher Peres

1995-01-05T23:59:59.000Z

195

Bohmian mechanics, the quantum-classical correspondence and the classical limit: the case of the square billiard  

E-Print Network [OSTI]

Square billiards are quantum systems complying with the dynamical quantum-classical correspondence. Hence an initially localized wavefunction launched along a classical periodic orbit evolves along that orbit, the spreading of the quantum amplitude being controlled by the spread of the corresponding classical statistical distribution. We investigate wavepacket dynamics and compute the corresponding de Broglie-Bohm trajectories in the quantum square billiard. We also determine the trajectories and statistical distribution dynamics for the equivalent classical billiard. Individual Bohmian trajectories follow the streamlines of the probability flow and are generically non-classical. This can also hold even for short times, when the wavepacket is still localized along a classical trajectory. This generic feature of Bohmian trajectories is expected to hold in the classical limit. We further argue that in this context decoherence cannot constitute a viable solution in order to recover classicality.

A. Matzkin

2008-06-19T23:59:59.000Z

196

KH Computational Physics-2009 Density Functional Theory (DFT) Density Functional Theory  

E-Print Network [OSTI]

KH Computational Physics- 2009 Density Functional Theory (DFT) Density Functional Theory of interacting particles. Kristjan Haule, 2009 ­2­ #12;KH Computational Physics- 2009 Density Functional Theory functional of n. Kristjan Haule, 2009 ­3­ #12;KH Computational Physics- 2009 Density Functional Theory (DFT

Haule, Kristjan

197

Hydrogen storage in LiAlH4 : Predictions of the crystal structures and reaction mechanisms of intermediate phases from quantum mechanics  

E-Print Network [OSTI]

Hydrogen storage in LiAlH4 : Predictions of the crystal structures and reaction mechanisms in decomposition of the potential hydrogen storage material LiAlH4 . First, we explore the decomposition mechanism in the development of small light- weight hydrogen storage methods1,2 for automotive applica- tions. Hydrogen fuel

Goddard III, William A.

198

Putting DFT to the Test: A First Principles Study of Electronic, Magnetic and Optical Properties of Co3O4  

Science Journals Connector (OSTI)

Putting DFT to the Test: A First Principles Study of Electronic, Magnetic and Optical Properties of Co3O4 ...

Vijay Singh; Monica Kosa; Koushik Majhi; Dan Thomas Major

2014-11-25T23:59:59.000Z

199

Circumveiloped by Obscuritads. The nature of interpretation in quantum mechanics, hermeneutic circles and physical reality, with cameos of James Joyce and Jacques Derrida  

E-Print Network [OSTI]

The quest for finding the right interpretation of Quantum Mechanics (QM) is as old als QM and still has not ended, and may never end. The question what an interpretation of QM is has hardly ever been raised explicitly, let alone answered. We raise it and answer it. Then the quest for the right interpretation can continue self-consciously, for we then know exactly what we are after. We present a list of minimal requirements that something has to meet in order to qualify as an interpretation of QM. We also raise, as a side issue, the question how the discourse on the interpretation of QM relates to hermeneutics in Continental Philosophy.

F. A. Muller

2014-06-21T23:59:59.000Z

200

Remarks on an attempted axiomatisation of Quantum Mechanics, due to Lucien Hardy, and Ten Theses on Hilbert's Sixth Problem and Quantum Measurement  

E-Print Network [OSTI]

From the standpoint of Hilbert's Sixth Problem, which is the axiomatisation of Physics, the famous paper of Lucien Hardy's, Quantum Theory from Five Reasonable Axioms, is not relevant. The present paper argues that Hardy does not give a physical definition of `limit', and if we assume the usual mathematical definition of limit of a sequence, he fails to define a sequence in physical terms to which the usual definition is applicable. We argue that one should not, in fact, try to define probability in terms of the usual notion of limit of a sequence of results of a measurement because of seemingly insurmountable difficulties in axiomatising the notion of function or sequence in this context. Von Plato's and the authour's work (see http:arxiv.org/abs/quant-ph/0502124 and euclid.unh.edu/~jjohnson/axiomatics.html for larger context and further references) on the definition of physical probability needs to be used in this context. We conclude with ten theses on quantum measurement, from the standpoint of the Hilbert problem.

Joseph F. Johnson

2006-06-15T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

EERE PROJECT MANAGEMENT CENTER NFPA DFT1!lUIINATION  

Broader source: Energy.gov (indexed) [DOE]

OFEN:rRGY OFEN:rRGY EERE PROJECT MANAGEMENT CENTER NFPA DFT1!lUIINATION Page 1 of2 RECIPIENT:Middlesex Community College STATE: MA PROJECf TITLE: Middlesex Community College - Geothermal Project Funding Opportunity Announcement Number Procurement Instrument Number NEPA Control Number CID Number N/A DE-EEOOOO323 GF0-0000323-002 EE323 Based on my review ofthe information concerning the proposed action, as NEPA Compliance Officer (authorized under DOE Order 4SI.IA), I have made the following determination: ex, EA, EIS APPENDIX AND NUMBER: Description: A9 Inf ormation gathering, analYSiS, and dissemination 82.1 Workplace enhancements B2.2 Building and equipment instrumentation Information gathering (including, but not limited to, literature surveys, inventories, site visits, and audils),

202

DFT investigation on the electronic structure of Faujasite  

SciTech Connect (OSTI)

We report here first-principle pseudopotential DFT calculations to investigate relevant aspects of the electronic structure of zeolites based FAU. Fundamental molecular issues of the band-gap and electronic population analysis were reviewed under GGA/RPBE level of theory, corroborated with a DZP basis set and Troullier-Martins norm conserving pseudo-potentials. The atom-projected density of states and the analysis of HOMO-LUMO frontier orbitals at Gamma point were performed. Their electronic transfers are discussed through the alignment and relative positions of orbitals in order to determine the way that the molecule interacts with adsorbed molecules and other practical applications. Mulliken population analysis was employed for describing atomic charge distribution in the chosen systems.

Popeneciu, Horea; Calborean, Adrian; Tudoran, Cristian; Buimaga-Iarinca, Luiza [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)

2013-11-13T23:59:59.000Z

203

Triplet absorption in carbon nanotubes: a TD-DFT study  

E-Print Network [OSTI]

We predict properties of triplet excited states in single-walled carbon nanotubes (CNTs) using a time-dependent density-functional theory (TD-DFT). We show that the lowest triplet state energy in CNTs to be about 0.2-0.3 eV lower than the lowest singlet states. Like in $\\pi$-conjugated polymers, the lowest CNT triplets are spatially localized. These states show strong optical absorption at about 0.5-0.6 eV to the higher lying delocalized triplet states. These results demonstrate striking similarity of the electronic features between CNTs and $\\pi$-conjugated polymers and provide explicit guidelines for spectroscopic detection of CNT triplet states.

Sergei Tretiak

2007-02-13T23:59:59.000Z

204

Quantum spin dynamics  

E-Print Network [OSTI]

The classical Landau-Lifshitz equation has been derived from quantum mechanics. Starting point is the assumption of a non-Hermitian Hamilton operator to take the energy dissipation into account. The corresponding quantum mechanical time dependent Schr\\"odinger, Liouville and Heisenberg equation have been described and the similarities and differences between classical and quantum mechanical spin dynamics have been discussed. Furthermore, a time dependent Schr\\"odinger equation corresponding to the classical Landau-Lifshitz-Gilbert equation and two ways to include temperature into the quantum mechanical spin dynamics have been proposed.

Robert Wieser

2014-10-23T23:59:59.000Z

205

Contact Resistance for "End-Contacted" Metal-Graphene and Metal-Nanotube Interfaces from Quantum Mechanics  

E-Print Network [OSTI]

ballistic conductance,12-14 and high thermal conductivity.15 Indeed, significant progress has been made layer graphene has been demonstrated to exhibit high electron mobility (15 000 cm2 /(V s)) and thermalContact Resistance for "End-Contacted" Metal-Graphene and Metal-Nanotube Interfaces from Quantum

Goddard III, William A.

206

DFT calculations on nitrodiborane compounds as new potential high energy materials  

Science Journals Connector (OSTI)

We have used DFT methods to determine the structures and thermochemistry of several nitro-substituted diborane molecules in an attempt to rate their potential as high energy materials. The properties of nitrodibo...

John Abdelmalik; David W. Ball

2010-05-01T23:59:59.000Z

207

DFT calculations of EPR parameters of transition metal complexes: Implications for catalysis  

SciTech Connect (OSTI)

Transition metal and ligand hyperfine coupling constants for paramagnetic vanadium and copper model complexes have been calculated using DFT methods that are available in commercial software packages. Variations in EPR parameters with ligand identity and ligand orientation are two of the trends that have been investigated with DFT calculations. For example, the systematic variation of the vanadium hyperfine coupling constant with orientation for an imidazole ligand in a VO2+ complex has been observed experimentally and has also been reproduced by DFT calculations. Similarly, changes in the vanadium hyperfine coupling constant with ligand binding have been calculated using model complexes and DFT methods. DFT methods were also used to calculate ligand hyperfine coupling constants in transition metal systems. The variation of the proton hyperfine coupling constant with water ligand orientation was investigated for [VO(H2O)5]2+ and the results were used to interpret high resolution EPR data of VO2+-exchanged zeolites. Nitrogen hyperfine and quadrupole coupling constants for VO2+ model complexes were calculated and compared with experimental data. The computational results were used to enhance the interpretation of the EPR data for vanadium-exchanged zeolites which are promising catalytic materials. The implications of the DFT calculations of EPR parameters with respect to catalysis will be discussed

Saladino, Alexander C.; Larsen, Sarah C.

2005-07-15T23:59:59.000Z

208

Study of methods for lowering the lasing frequency of a terahertz quantum-cascade laser based on two quantum wells  

Science Journals Connector (OSTI)

Two mechanisms for achieving lower terahertz-range frequencies in quantum-cascade structures with two quantum wells based on GaAs/AlGaAs compounds are ... mechanism is based on the introduction of composite quantum

D. V. Ushakov; Yu. G. Sadofyev; N. Samal

2012-11-01T23:59:59.000Z

209

On Quantum Capacity and its Bound  

E-Print Network [OSTI]

The quantum capacity of a pure quantum channel and that of classical-quantum-classical channel are discussed in detail based on the fully quantum mechanical mutual entropy. It is proved that the quantum capacity generalizes the so-called Holevo bound.

Masanori Ohya; Igor V. Volovich

2004-06-29T23:59:59.000Z

210

That quantum mechanics is a probabilistic theory was, by 1964, an old but still troubling story. The fact that identical  

E-Print Network [OSTI]

mechanics was famously expressed in Albert Einstein's assertion that "God doesn't play dice." By 1964 most happens after t1 but also for what happened in the past. Suppose we start with an ensemble of particles subject each particle to some measurement and then we perform a final measurement at t1. We can then split

Wüthrich, Christian

211

Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex--Electronic structure,  

E-Print Network [OSTI]

Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex--Electronic structure 2008 Abstract This study presents molecular orbital/density functional theory (MO/DFT) calculations of the electronic structure, vibra- tional frequencies, and equilibrium isotope fractionation factors for iron

Sparks, Donald L.

212

Calculus for Functions of Noncommuting Operators and General Phase-Space Methods in Quantum Mechanics. I. Mapping Theorems and Ordering of Functions of Noncommuting Operators  

Science Journals Connector (OSTI)

A new calculus for functions of noncommuting operators is developed, based on the notion of mapping of functions of operators onto c-number functions. The class of linear mappings, each member of which is characterized by an entire analytic function of two complex variables, is studied in detail. Closed-form solutions for such mappings and for the inverse mappings are obtained and various properties of these mappings are studied. It is shown that the most commonly occurring rules of association between operators and c-numbers (the Weyl, the normal, the antinormal, the standard, and the antistandard rules) belong to this class and are, in fact, the simplest ones in a clearly defined sense. It is shown further that the problem of expressing an operator in an ordered form according to some prescribed rule is equivalent to an appropriate mapping of the operator on a c-number space. The theory provides a systematic technique for the solution of numerous quantum-mechanical problems that were treated in the past by ad hoc methods, and it furnishes a new approach to many others. This is illustrated by a number of examples relating to mappings and ordering of operators.

G. S. Agarwal and E. Wolf

1970-11-15T23:59:59.000Z

213

Quantum Monte Carlo calculations of strongly correlated materials...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

correlations and quantum mechanics. I will talk about our efforts to use high performance computing to directly simulate many-body quantum problems for these materials. This...

214

Shared access to quantum information  

Science Journals Connector (OSTI)

It is shown that quantum mechanics allows a qubit to be transferred so that it can be accessed symmetrically by two observers. These can then decide later which one is to take possession of the quantum information. The process is not fully successful, but a failed experiment may allow the retention of the quantum information for use in a subsequent operation.

Stig Stenholm and Erika Andersson

2000-09-11T23:59:59.000Z

215

Computational Study on the Working Mechanism of a Stilbene Light-Driven Molecular Rotary Motor: Sloped Minimal Energy Path and Unidirectional Nonadiabatic Photoisomerization  

Science Journals Connector (OSTI)

In 2009, Torras et al.(7) reported a DFT and MP2 study on the ground-state rotational profiles of a molecular gearbox [9-(2,3-dihydro-2-phenyl-1H-benz[e)inden-1-ylidene)-9H-fluorene]. Later, Kazaryan et al. reported their calculation on the ground (S0) and first excited singlet (S1) states of an overcrowded biphenanthrylidene [(3R,3?R)-(P,P)-trans-1,1?,2,2?,3,3?,4,4?-octahydro-3,3?-dimethyl-4,4?-biphenanthrylidene] molecular motor by state-averaged spin restricted ensemble-referenced KohnSham (SA-REKS) methods,(8a) and on its excited-state dynamics by a classical OPLS force field method(8b) and semiclassical surface hopping dynamics with a semiempirical quantum mechanics Hamiltonian (OM2/GUGA-MRCI). ... Molecular Rotors and Motors: Recent Advances and Future Challenges ...

Fengyi Liu; Keiji Morokuma

2012-02-13T23:59:59.000Z

216

Parasupersymmetry in Quantum Graphs  

E-Print Network [OSTI]

We study hidden parasupersymmetry structures in purely bosonic quantum mechanics on compact equilateral graphs. We consider a single free spinless particle on the graphs and show that the Huang-Su parasupersymmetry algebra is hidden behind degenerate spectra.

Satoshi Ohya

2012-10-29T23:59:59.000Z

217

Parasupersymmetry in Quantum Graphs  

E-Print Network [OSTI]

We study hidden parasupersymmetry structures in purely bosonic quantum mechanics on compact equilateral graphs. We consider a single free spinless particle on the graphs and show that the Rubakov-Spiridonov-Khare-Tomiya parasupersymmetries are hidden behind degenerate spectra.

Ohya, Satoshi

2012-01-01T23:59:59.000Z

218

Semiconductors Used in Photovoltaic and Photocatalytic Devices: Assessing Fundamental Properties from DFT  

Science Journals Connector (OSTI)

Semiconductors Used in Photovoltaic and Photocatalytic Devices: Assessing Fundamental Properties from DFT ... In a dielectric environment, the electrostatic force between the electron and the hole can be approximated by the eq 1. ... Madelung, O. Semiconductors: Data Handbook, 3rd ed.; Springer: New York, 2004. ...

Tangui Le Bahers; Michel Rrat; Philippe Sautet

2014-02-28T23:59:59.000Z

219

TEDTTC^/Dft Ris-R-641(pN) Methodology forJustification and  

E-Print Network [OSTI]

and optimization of protective mea- sures in case of a reactor accident situation with a large release of fissionTEDTTC^/Dft Risø-R-641(pN) Methodology forJustification and Optimization ofProtective Measures: *»***&*> Methodology forJustification and Optimization of Protective Measures Including a Case Study: Protective

220

A DFT Study of Ethanol Adsorption and Dehydrogenation on Cu/Cr2O3 Catalyst  

Science Journals Connector (OSTI)

In this work, DFT simulation method was used to study the adsorption and dehydrogenation of ethanol on Cu/Cr2O3 catalyst. Firstly, the stable configuration of Cu4 cluster adsorbed on Cr2O3...(001) surface was stu...

Minhua Zhang; Yanping Huang; Ruzhen Li; Guiming Li; Yingzhe Yu

2014-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Quantum Privacy and Quantum Coherence  

Science Journals Connector (OSTI)

We derive a simple relation between a quantum channel's capacity to convey coherent (quantum) information and its usefulness for quantum cryptography.

Benjamin Schumacher and Michael D. Westmoreland

1998-06-22T23:59:59.000Z

222

Amplified Quantum Transforms  

E-Print Network [OSTI]

In this thesis we investigate two new Amplified Quantum Transforms. In particular we create and analyze the Amplified Quantum Fourier Transform (Amplified-QFT) and the Amplified-Haar Wavelet Transform. First, we provide a brief history of quantum mechanics and quantum computing. Second, we examine the Amplified-QFT in detail and compare it against the Quantum Fourier Transform (QFT) and Quantum Hidden Subgroup (QHS) algorithms for solving the Local Period Problem. We calculate the probabilities of success of each algorithm and show the Amplified-QFT is quadratically faster than the QFT and QHS algorithms. Third, we examine the Amplified-QFT algorithm for solving The Local Period Problem with an Error Stream. Fourth, we produce an uncertainty relation for the Amplified-QFT algorithm. Fifth, we show how the Amplified-Haar Wavelet Transform can solve the Local Constant or Balanced Signal Decision Problem which is a generalization of the Deutsch-Jozsa algorithm.

David Cornwell

2014-06-01T23:59:59.000Z

223

Generalization of internal Density Functional Theory and Kohn-Sham scheme to multicomponent systems, and link with traditional DFT  

E-Print Network [OSTI]

We generalize the recently developped "internal" Density Functional Theory (DFT) and Kohn-Sham scheme to multicomponent systems. We obtain a general formalism, applicable for the description of multicomponent self-bound systems (as molecules where the nuclei are treated explicitely, atomic nuclei and mix of 3He and 4He droplets), where the fundamental translational symmetry has been treated correctly. The main difference with traditional DFT is the explicit inclusion of center-of-mass correlations in the functional. A large part of the paper is dedicated to the application to molecules, which permits among other to clarify the approximations that underly traditional DFT.

Jeremie Messud

2011-11-21T23:59:59.000Z

224

Optimal measurements in quantum mechanics  

E-Print Network [OSTI]

Four common optimality criteria for measurements are formulated using relations in the set of observables, and their connections are clarified. As case studies, 1-0 observables, localization observables, and photon counting observables are considered.

T. Heinonen

2005-08-31T23:59:59.000Z

225

Large scale quantum mechanical enzymology  

E-Print Network [OSTI]

conventional QM methods but, due to the computational costs, as will be discussed later in this dissertation, the system sizes accessible with these approaches do not reach the requirements for studying biomolecular systems. A particularly successful brand... imaging allow certain structural information to be extracted, such as interatomic distances and torsion angles. In the all important quest for experimental agreement, it would be all too easy to assert that if simulations generate the same result...

Lever, Greg

2014-10-07T23:59:59.000Z

226

Quantum mechanics versus equivalence principle  

SciTech Connect (OSTI)

We consider the scattering of a photon by a weak gravitational field, treated as an external field, up to second order of the perturbation expansion. The resulting cross section is energy dependent which indicates a violation of Galileo's equivalence principle (universality of free fall) and, consequently, of the classical equivalence principle. The deflection angle {theta} for a photon passing by the sun is evaluated afterward and the likelihood of detecting ({delta}{theta}/{theta}{sub E}){identical_to}({theta}-{theta}{sub E}/{theta}{sub E}) (where {theta}{sub E} is the value predicted by Einstein's geometrical theory for the light bending) in the foreseeable future, is discussed.

Accioly, Antonio [Laboratorio de Fisica Experimental (LAFEX), Centro Brasileiro de Pesquisas Fisicas (CBPF), Rua Dr. Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil); Group of Field Theory from First Principles, Laboratorio de Fisica Experimental (LAFEX), Centro Brasileiro de Pesquisas Fisicas (CBPF), Rua Dr. Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil); Instituto de Fisica Teorica (IFT), Sao Paulo State University (UNESP), Rua Pamplona 145, 01405-000, Sao Paulo, SP (Brazil); Paszko, Ricardo [Group of Field Theory from First Principles, Laboratorio de Fisica Experimental (LAFEX), Centro Brasileiro de Pesquisas Fisicas (CBPF), Rua Dr. Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ (Brazil)

2008-09-15T23:59:59.000Z

227

Density-functional theory of freezing of quantum liquids at zero temperature using exact liquid-state linear response  

E-Print Network [OSTI]

Density-functional theory of freezing of quantum liquids at zero temperature using exact liquid the shortcomings of the currently popular density-functional approximate theories to describe 3d freezing distances. S0163-1829 97 04310-5 I. INTRODUCTION The modern density-functional theory DFT , which

Likos, Christos N.

228

Ions in solution: Density corrected density functional theory (DC-DFT)  

SciTech Connect (OSTI)

Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HOCl{sup ?} and HOH{sub 2}O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent.

Kim, Min-Cheol; Sim, Eunji, E-mail: esim@yonsei.ac.kr [Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 (Korea, Republic of)] [Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Burke, Kieron [Department of Chemistry, University of California, Irvine, California 92697 (United States)] [Department of Chemistry, University of California, Irvine, California 92697 (United States)

2014-05-14T23:59:59.000Z

229

Layered Tantalum Oxynitride Nanorod Array Carpets for Efficient Photoelectrochemical Conversion of Solar Energy: Experimental and DFT Insights  

Science Journals Connector (OSTI)

Layered Tantalum Oxynitride Nanorod Array Carpets for Efficient Photoelectrochemical Conversion of Solar Energy: Experimental and DFT Insights ... This difference in bond energy resulted in narrower band gap energies in oxynitrides compared to their metal oxide counterparts. ...

Nageh K. Allam; Basamat S. Shaheen; Ahmed M. Hafez

2014-03-25T23:59:59.000Z

230

How do vibrations change their composition upon electronic excitation? EXSY-T2D-IR measurements challenge DFT calculations.  

Science Journals Connector (OSTI)

The composition of excited state vibrations can be disentangled by projecting ground state vibrations on them using exchange transient two-dimensional IR spectroscopy. The results challenge excited state DFT c...

Andreas Messmer; Ana-Maria Blanco Rodrguez; Jakub ebera

2009-01-01T23:59:59.000Z

231

Quantum Tetrahedra  

E-Print Network [OSTI]

We discuss in details the role of Wigner 6j symbol as the basic building block unifying such different fields as state sum models for quantum geometry, topological quantum field theory, statistical lattice models and quantum computing. The apparent twofold nature of the 6j symbol displayed in quantum field theory and quantum computing -a quantum tetrahedron and a computational gate- is shown to merge together in a unified quantum-computational SU(2)-state sum framework.

Mauro Carfora; Annalisa Marzuoli; Mario Rasetti

2010-01-25T23:59:59.000Z

232

Molecular Binding in Post-KohnSham Orbital-Free DFT  

Science Journals Connector (OSTI)

Alex Borgoo *, James A. Green , and David J. Tozer * ... Molecular binding in post-KohnSham orbital-free DFT is investigated, using noninteracting kinetic energy functionals that satisfy the uniform electron gas condition and which are inhomogeneous under density scaling. ... A parameter is introduced that quantifies binding, and a series of functionals are determined from fits to near-exact effective homogeneities and/or KohnSham noninteracting kinetic energies. ...

Alex Borgoo; James A. Green; David J. Tozer

2014-10-30T23:59:59.000Z

233

Combined Investigation of Water Sorption on TiO2 Rutile (110) Single Crystal Face: XPS vs. Periodic DFT  

E-Print Network [OSTI]

1 Combined Investigation of Water Sorption on TiO2 Rutile (110) Single Crystal Face: XPS vs(0)169157150; e-mail: roques@ipno.in2p3.fr Keywords: water, sorption, rutile TiO2, (110), XPS, DFT. Abstract XPS and periodic DFT calculations have been used to investigate water sorption on the TiO2 rutile (110) face. Two

Paris-Sud XI, Université de

234

The Dirac equation in electronic structure calculations: Accurate evaluation of DFT predictions for actinides  

SciTech Connect (OSTI)

Brooks, Johansson, and Skriver, using the LMTO-ASA method and considerable insight, were able to explain many of the ground state properties of the actinides. In the many years since this work was done, electronic structure calculations of increasing sophistication have been applied to actinide elements and compounds, attempting to quantify the applicability of DFT to actinides and actinide compounds and to try to incorporate other methodologies (i.e. DMFT) into DFT calculations. Through these calculations, the limits of both available density functionals and ad hoc methodologies are starting to become clear. However, it has also become clear that approximations used to incorporate relativity are not adequate to provide rigorous tests of the underlying equations of DFT, not to mention ad hoc additions. In this talk, we describe the result of full-potential LMTO calculations for the elemental actinides, comparing results obtained with a full Dirac basis with those obtained from scalar-relativistic bases, with and without variational spin-orbit. This comparison shows that the scalar relativistic treatment of actinides does not have sufficient accuracy to provide a rigorous test of theory and that variational spin-orbit introduces uncontrolled errors in the results of electronic structure calculations on actinide elements.

Wills, John M [Los Alamos National Laboratory; Mattsson, Ann E [Sandia National Laboratories

2012-06-06T23:59:59.000Z

235

Quantum correlation via quantum coherence  

E-Print Network [OSTI]

Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes of quantum coherence. We propose a revised measure for total coherence and find that this measure can lead to a symmetric version of geometric quantum correlation which is analytic for two qubits. In particular, this measure can also arrive at a monogamy equality on the distribution of quantum coherence. Finally, we also quantify a remaining type of quantum coherence and find that for two qubits it is directly connected with quantum nonlocality.

Chang-shui Yu; Yang Zhang; Haiqing Zhao

2014-02-19T23:59:59.000Z

236

Assessing the density functional theory-based multireference configuration interaction (DFT/MRCI) method for transition metal complexes  

SciTech Connect (OSTI)

We report an assessment of the performance of density functional theory-based multireference configuration interaction (DFT/MRCI) calculations for a set of 3d- and 4d-transition metal (TM) complexes. The DFT/MRCI results are compared to published reference data from reliable high-level multi-configurational ab initio studies. The assessment covers the relative energies of different ground-state minima of the highly correlated CrF{sub 6} complex, the singlet and triplet electronically excited states of seven typical TM complexes (MnO{sub 4}{sup ?}, Cr(CO){sub 6}, [Fe(CN){sub 6}]{sup 4?}, four larger Fe and Ru complexes), and the corresponding electronic spectra (vertical excitation energies and oscillator strengths). It includes comparisons with results from different flavors of time-dependent DFT (TD-DFT) calculations using pure, hybrid, and long-range corrected functionals. The DFT/MRCI method is found to be superior to the tested TD-DFT approaches and is thus recommended for exploring the excited-state properties of TM complexes.

Escudero, Daniel, E-mail: escudero@kofo.mpg.de, E-mail: thiel@kofo.mpg.de; Thiel, Walter, E-mail: escudero@kofo.mpg.de, E-mail: thiel@kofo.mpg.de [Max-Planck-Institut fr Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mlheim an der Ruhr (Germany)] [Max-Planck-Institut fr Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mlheim an der Ruhr (Germany)

2014-05-21T23:59:59.000Z

237

Quantum Metropolis Sampling  

E-Print Network [OSTI]

The original motivation to build a quantum computer came from Feynman who envisaged a machine capable of simulating generic quantum mechanical systems, a task that is believed to be intractable for classical computers. Such a machine would have a wide range of applications in the simulation of many-body quantum physics, including condensed matter physics, chemistry, and high energy physics. Part of Feynman's challenge was met by Lloyd who showed how to approximately decompose the time-evolution operator of interacting quantum particles into a short sequence of elementary gates, suitable for operation on a quantum computer. However, this left open the problem of how to simulate the equilibrium and static properties of quantum systems. This requires the preparation of ground and Gibbs states on a quantum computer. For classical systems, this problem is solved by the ubiquitous Metropolis algorithm, a method that basically acquired a monopoly for the simulation of interacting particles. Here, we demonstrate how to implement a quantum version of the Metropolis algorithm on a quantum computer. This algorithm permits to sample directly from the eigenstates of the Hamiltonian and thus evades the sign problem present in classical simulations. A small scale implementation of this algorithm can already be achieved with today's technology

K. Temme; T. J. Osborne; K. G. Vollbrecht; D. Poulin; F. Verstraete

2009-11-18T23:59:59.000Z

238

Statistical Mechanics of Amplifying Apparatus  

E-Print Network [OSTI]

We implement Feynman's suggestion that the only missing notion needed for the puzzle of Quantum Measurement is the statistical mechanics of amplifying apparatus. We define a thermodynamic limit of quantum amplifiers which is a classically describable system in the sense of Bohr, and define macroscopic pointer variables for the limit system. Then we derive the probabilities of Quantum Measurement from the deterministic Schroedinger equation by the usual techniques of Classical Statistical Mechanics.

Joseph Johnson

2005-02-08T23:59:59.000Z

239

Quantum Imaging Technologies  

E-Print Network [OSTI]

Over the past three decades, quantum mechanics has allowed the development of technologies that provide unconditionally secure communication. In parallel, the quantum nature of the transverse electromagnetic field has spawned the field of quantum imaging that encompasses technologies such as quantum ghost imaging and high-dimensional quantum key distribution (QKD). The emergence of such quantum technologies also highlights the need for the development of methods for characterizing the elusive quantum state itself. In this document, we describe new technologies that use the quantum properties of light for security. The first is a technique that extends the principles behind QKD to the field of imaging. By applying the polarization-based BB84 protocol to individual photons in an active imaging system, we obtained images that are secure against intercept-resend jamming attacks. The second technology presented in this article is based on an extension of quantum ghost imaging. We used a holographic filtering technique to build a quantum ghost image identification system that uses a few pairs of photons to identify an object from a set of known objects. The third technology addressed in this document is a high-dimensional QKD system that uses orbital-angular-momentum (OAM) modes of light for encoding. Moving to a high-dimensional state space in QKD allows one to impress more information on each photon, as well as introduce higher levels of security. We discuss the development of two OAM-QKD protocols based on the BB84 and Ekert QKD protocols. The fourth and final technology presented in this article is a relatively new technique called direct measurement that uses sequential weak and strong measurements to characterize a quantum state. We use this technique to characterize the quantum state of a photon with a dimensionality of d=27, and measure its rotation in the natural basis of OAM.

Mehul Malik; Robert W. Boyd

2014-06-06T23:59:59.000Z

240

Quantum Detection and Invisibility in Coherent Nanostructures  

SciTech Connect (OSTI)

We address quantum invisibility in the context of electronics in nanoscale quantum structures. In analogy with metamaterials, we use the freedom of design that quantum corrals provide and show that quantum mechanical objects can be hidden inside the corral, with respect to inelastic electron scattering spectroscopy in combination with scanning tunneling microscopy, and we propose a design strategy. A simple illustration of the invisibility is given in terms of an elliptic quantum corral containing a molecule, with a local vibrational mode, at one of the foci. Our work has implications to quantum information technology and presents new tools for nonlocal quantum detection and distinguishing between different molecules.

Fransson, J.

2010-04-28T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Derivation of quantum probabilities from deterministic evolution  

E-Print Network [OSTI]

The predictions of quantum mechanics are probabilistic. Quantum probabilities are extracted using a postulate of the theory called the Born rule, the status of which is central to the "measurement problem" of quantum mechanics. Efforts to justify the Born rule from other physical principles, and thus elucidate the measurement process, have involved lengthy statistical or information-theoretic arguments. Here we show that Bohm's deterministic formulation of quantum mechanics allows the Born rule for measurements on a single system to be derived, without any statistical assumptions. We solve a simple example where the creation of an ensemble of identical quantum states, together with position measurements on those states, are described by Bohm's quantum dynamics. The calculated measurement outcomes agree with the Born-rule probabilities, which are thus a consequence of deterministic evolution. Our results demonstrate that quantum probabilities can emerge from simple dynamical laws alone, and they support the view that there is no underlying indeterminism in quantum phenomena.

T. G. Philbin

2014-10-15T23:59:59.000Z

242

Intrinsic Time Quantum Geometrodynamics  

E-Print Network [OSTI]

Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental canonical commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

Eyo Eyo Ita III; Chopin Soo; Hoi-Lai Yu

2015-01-26T23:59:59.000Z

243

Smartphone data safety with quantum cryptography  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Smartphone data safety with quantum cryptography Smartphone data safety with quantum cryptography Smartphone data safety with quantum cryptography Laws of quantum physics and information theory ensure that smartphones with QKarD could never be compromised. January 20, 2012 The QKarD encodes security keys on a photon using quantum mechanical principles. The miniature transmitter communicates with a trusted authority to generate random cryptographic keys to encode and decode information. The QKarD encodes security keys on a photon using quantum mechanical principles. The laws of quantum physics and information theory ensure that these keys never can be cracked, regardless of advancements in computer technology. New technology brings quantum cryptography to handhelds Laws of quantum physics and information theory ensure that smartphones with

244

Quantum Locality?  

SciTech Connect (OSTI)

Robert Griffiths has recently addressed, within the framework of a consistent quantum theory (CQT) that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues, on the basis of his examination of certain arguments that claim to demonstrate the existence of such nonlocal influences, that such influences do not exist. However, his examination was restricted mainly to hidden-variable-based arguments that include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by attributing to the system properties alien to that system. Hence Griffiths rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his consistent quantum theory shows that the cited proof is valid within that restrictive framework. This necessary existence, within the consistent framework, of long range essentially instantaneous influences refutes the claim made by Griffiths that his consistent framework is superior to the orthodox quantum theory of von Neumann because it does not entail instantaneous influences. An added section responds to Griffiths reply, which cites a litany of ambiguities that seem to restrict, devastatingly, the scope of his CQT formalism, apparently to buttress his claim that my use of that formalism to validate the nonlocality theorem is flawed. But the vagaries that he cites do not upset the proof in question. It is show here in detail why the precise statement of this theorem justifies the specified application of CQT. It is also shown, in response to his challenge, why a putative proof of locality that he has proposed is not valid.

Stapp, Henry

2011-11-10T23:59:59.000Z

245

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the...

246

Ab-initio friction forces on the nanoscale: A DFT study of fcc Cu(111)  

E-Print Network [OSTI]

While there are a number of models that tackle the problem of calculating friction forces on the atomic level, providing a completely parameter-free approach remains a challenge. Here we present a quasi-static model to obtain an approximation to the nanofrictional response of dry, wearless systems based on quantum mechanical all-electron calculations. We propose a mechanism to allow dissipative sliding, which relies on atomic relaxations. We define two different ways of calculating the mean nanofriction force, both leading to an exponential friction-versus-load behavior for all sliding directions. Since our approach does not impose any limits on lengths and directions of the sliding paths, we investigate arbitrary sliding directions for an fcc Cu(111) interface and detect two periodic paths which form the upper and lower bound of nanofriction. For long aperiodic paths the friction force convergences to a value in between these limits. For low loads we retrieve the Derjaguin generalization of Amontons-Coulomb kinetic friction law which appears to be valid all the way down to the nanoscale. We observe a non-vanishing Derjaguin-offset even for atomically flat surfaces in dry contact.

Michael Wolloch; Gregor Feldbauer; Peter Mohn; Josef Redinger; Andrs Vernes

2014-08-26T23:59:59.000Z

247

Quantum Institute  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Quantum Institute Quantum Institute Quantum Institute A new research frontier awaits! Our door is open and we thrive on mutually beneficial partnerships, collaborations that drive innovations and new technologies. Contact Leader Malcolm Boshier (505) 665-8892 Email Two of LANL's most successful quantum technology initiatives: quantum cryptography and the race for quantum computer The area of quantum information, science, and technology is rapidly evolving, with important applications in the areas of quantum cryptography, quantum computing, quantum metrology, and advanced quantum-based sensors, some of which are directly relevant to the Laboratory's national security mission. Mission Foster a vigorous intellectual environment at LANL Define and develop strategic thrusts Target and pursue funding opportunities

248

Quantum-enhanced absorption refrigerators  

E-Print Network [OSTI]

Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators.

Luis A. Correa; Jos P. Palao; Daniel Alonso; Gerardo Adesso

2013-08-19T23:59:59.000Z

249

Modeling of molecular gas adsorption isotherms on porous materials with hybrid PC-SAFTDFT  

Science Journals Connector (OSTI)

Abstract The developed hybrid PC-SAFTDFT model, a coupling of density functional theory (DFT) with perturbed-chain statistical associating fluid theory (PC-SAFT), was used to study the adsorption of pure- and mixed-fluids on nano-porous materials, and carbons and zeolites were chosen as examples of nano-porous materials in this work for model performance evaluation. In the PC-SAFTDFT model, the modified fundamental measure theory was used for the hard sphere contribution, the dispersion free energy functional was represented with a weighted density approximation, and the chain free energy functional from interfacial SAFT was used to account for the chain connectivity. The fluid was modeled as a chain molecule with molecular parameters taken from those in the bulk PC-SAFT. The external force field was used to describe the interaction between the solid surface of a nano-porous material and fluid. Application of this model was demonstrated on the gas adsorption on porous carbons and zeolites which were assumed to have slit- and cylinder-shaped pores with mean pore sizes, respectively. The parameters of the adsorption model were obtained by fitting to the pure-gas adsorption isotherms measured experimentally. With parameters of the model fitted to the pure-gas adsorption at one temperature, the model was used to predict the pure-gas adsorption at other temperatures as well as the adoption isotherms of mixtures. The model prediction was compared with the available experimental data, which shows that the predictions are reliable for most of the systems studied in this work. The effect of the pore size distribution on the model performance was further investigated, and it was found that the consideration of the pore size distribution (PSD) can improve the accuracy of the model results but the PSD analysis requires much more computing time.

Gulou Shen; Xiaohua Lu; Xiaoyan Ji

2014-01-01T23:59:59.000Z

250

Vacancy Mechanism Davydov I.А.  

National Nuclear Security Administration (NNSA)

9: Computational Physics-MD 9: Computational Physics-MD DFT and MD Simulation of Self-Diffusion in Silicon: Study of Diffusion Vacancy Mechanism Davydov I.А. * , Anisin А.V. † , Eliseev G.М. ‡ , Kopkin S.V. § , and Reese Jones ** *, †, ‡, § Russian Federal Nuclear Center - All-Russia Research Institute of Experimental Physics (RFNC-VNIIEF), 607190 Sarov, Mira-37, Russia ** Sandia National Laboratories, MS 9404, P.O. Box 0969, Livermore, CA 94551, USA Summary: Computations of jump activation energy DH j and diffusion jump frequency n have been carried out using the Density Functional Theory (DFT) and Molecular Dynamics (MD) method for a single crystal of Si. These parameters define the rate of vacancy diffusion transport.

251

On geometry influence on the behavior of a quantum mechanical scalar particle with intrinsic structure in external magnetic and electric fields  

E-Print Network [OSTI]

Relativistic theory of the Cox's scalar not point-like particle with intrinsic structure is developed on the background of arbitrary curved space-time. It is shown that in the most general form, the extended Proca-like tensor first order system of equations contains non minimal interaction terms through electromagnetic tensor F_{\\alpha \\beta} and Ricci tensor R_{\\alpha \\beta}. In relativistic Cox's theory, the limiting procedure to non-relativistic approximation is performed in a special class of curved space-time models. This theory is specified in simple geometrical backgrounds: Euclid's, Lobachevsky's, and Rie\\-mann's. Wave equation for the Cox's particle is solved exactly in presence of external uniform magnetic and electric fields in the case of Minkowski space. Non-trivial additional structure of the particle modifies the frequency of a quantum oscillator arising effectively in presence if external magnetic field. Extension of these problems to the case of the hyperbolic Lobachevsky space is examined. In presence of the magnetic field, the quantum problem in radial variable has been solved exactly; the quantum motion in z-direction is described by 1-dimensional Schr\\"{o}dinger-like equation in an effective potential which turns out to be too difficult for analytical treatment. In the presence of electric field, the situation is similar. The same analysis has been performed for spherical Riemann space model.

O. V. Veko; K. V. Kazmerchuk; E. M. Ovsiyuk; V. V. Kisel; V. M. Red'kov

2014-11-07T23:59:59.000Z

252

Transport mechanism of ?- and X-band electrons in AlxGa1-xAs/AlAs/GaAs double-barrier quantum-well infrared photodetectors  

Science Journals Connector (OSTI)

The effect of the ?- and X-band electrons in the Al0.25Ga0.75As/AlAs/GaAs double-barrier quantum well (DBQW) is investigated by a microscopic empirical pseudopotential calculation. The DBQW structure used in the calculation is designed as a 35-?m quantum-well infrared photodetector with an associated transition energy of 313 meV. DBQW tunneling transmission via ?- and X-like states as a function of electron energy and applied voltage are described and compared to that in a single-barrier AlAs/GaAs quantum well. The dark current is simulated by the confined ground-state electron tunneling out of the well. We find that, at high-bias voltage, tunneling via X-like states increases the current by a few orders of magnitude. We have also varied the additional barrier thickness and found that for a very thin (<20 ) additional barrier DBQW, the excited-state electrons are not blocked by the ?-band barrier, and may give a high photocurrent without the assistance of the X band, although the dark current also increases. 1996 The American Physical Society.

T. Osotchan; V. W. L. Chin; T. L. Tansley

1996-07-15T23:59:59.000Z

253

Quantum Money from Hidden Subspaces Scott Aaronson  

E-Print Network [OSTI]

Quantum Money from Hidden Subspaces Scott Aaronson Paul Christiano Abstract Forty years ago, Wiesner pointed out that quantum mechanics raises the striking possibility of money that cannot be counterfeited according to the laws of physics. We propose the first quantum money scheme that is (1) public

Aaronson, Scott

254

Quantum Machines  

E-Print Network [OSTI]

We discuss quantum information processing machines. We start with single purpose machines that either redistribute quantum information or identify quantum states. We then move on to machines that can perform a number of functions, with the function they perform being determined by a program, which is itself a quantum state. Examples of both deterministic and probabilistic programmable machines are given, and we conclude with a discussion of the utility of quantum programs.

Mark Hillery; Vladimir Buzek

2009-03-24T23:59:59.000Z

255

Dynamic modeling and optimal control of DFIG wind energy systems using DFT and NSGA-II  

Science Journals Connector (OSTI)

Abstract Once a doubly-fed induction generator (DFIG) is subjected to a disturbance by a change in the wind speed, the stator flux cannot change instantly. Under this condition, rotor back-EMF voltages reflect the effects of stator dynamics on rotor current dynamics, and have an important role on the oscillations of the rotor current. These oscillations decrease the DFIG system reliability and gear lifetime. Moreover, by focusing only on small signal analysis, the dynamic damping performance immediately following such disturbances is often degraded. Additional improvement in performance will be achieved if discrete Fourier transform (DFT) is used to quantify damping characteristic of the rotor current during changes of the operating points. This paper introduces an optimization technique based on non-dominated sorting genetic algorithm-II (NSGA-II) incorporating DFT analysis to achieve better control performance for DFIG system stability. Considering small signal stability, the main purpose of the control system in the present paper is to increase the system damping ratio as well as to guarantee enough stability margin. Eigenvalue analysis and time-domain simulations have been presented to demonstrate that the proposed optimizing method yields better control performance in comparison with one designed using mere eigenvalue relocation.

M. Zamanifar; B. Fani; M.E.H. Golshan; H.R. Karshenas

2014-01-01T23:59:59.000Z

256

Quantification of the Mercury Adsorption Mechanism on Brominated Activated  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Quantification of the Mercury Adsorption Mechanism on Brominated Activated Quantification of the Mercury Adsorption Mechanism on Brominated Activated Carbon Saturday, August 31, 2013 The primary anthropogenic source of mercury (Hg) emissions into the atmosphere is coal-fired power utilities. This work explores materials designed for Hg capture to be applied in the ductwork of a power plant to prevent Hg release into the atmosphere. Bench-scale combustion experiments have been carried out, in which sorbent materials were placed in a simulated flue gas stream doped with ppb levels of Hg. The sorbent surfaces were probed using x-ray absorption spectroscopy to determine the mechanism of Hg binding and to ultimately improve solvent design. The spectroscopy data was analyzed alongside results from density functional theory (DFT) for benchmarking so that DFT can be used as a screening tool for material

257

Quantum Information Science and Nanotechnology  

E-Print Network [OSTI]

In this note is touched upon an application of quantum information science (QIS) in nanotechnology area. The laws of quantum mechanics may be very important for nano-scale objects. A problem with simulating of quantum systems is well known and quantum computer was initially suggested by R. Feynman just as the way to overcome such difficulties. Mathematical methods developed in QIS also may be applied for description of nano-devices. Few illustrative examples are mentioned and they may be related with so-called fourth generation of nanotechnology products.

Alexander Yu. Vlasov

2009-03-06T23:59:59.000Z

258

EPR's reality criterion and quantum realism  

E-Print Network [OSTI]

We show that EPR's criterion of reality leads to contradictions in quantum mechanics. When locality is assumed, an inequality involving only one particle is violated, while when parameter and outcome dependence are assumed, EPR-realism is shown to be not Lorentz invariant. Quantum mechanics is both non-local and non-realistic.

Florin Moldoveanu

2012-11-18T23:59:59.000Z

259

An investigation of precision and scaling issues in nuclear spin and trapped-ion quantum simulators  

E-Print Network [OSTI]

Quantum simulation offers the possibility of using a controllable quantum-mechanical system to implement the dynamics of another quantum system, performing calculations that are intractable on classical computers for all ...

Clark, Robert J., Ph. D. Massachusetts Institute of Technology

2009-01-01T23:59:59.000Z

260

Integrated chips and optical cavities for trapped ion quantum information processing  

E-Print Network [OSTI]

Quantum information processing is a new and exciting field which uses quantum mechanical systems to perform information processing. At the heart of the excitement are quantum computation - which promises efficient algorithms ...

Leibrandt, David R

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Research in theResearch in the Joint Quantum InstituteJoint Quantum Institute  

E-Print Network [OSTI]

Coherent Quantum Phenomena · The Second Quantum Revolution ­ Beyond wave mechanics ­ Beyond quantized energies msingle Cd+ ion QC PlatformsQC Platforms SQUIDSSQUIDS Neutral Atoms in Optical Lattices Neutral Atoms construction Phillips, Porto, Rolston, Spielman Clark, Das Sarma, Galitski, Williams #12;Hybrid Quantum

Gruner, Daniel S.

262

Molecular structure calculations: A unified quantum mechanical description of electrons and nuclei using explicitly correlated Gaussian functions and the global vector representation  

SciTech Connect (OSTI)

We elaborate on the theory for the variational solution of the Schroedinger equation of small atomic and molecular systems without relying on the Born-Oppenheimer paradigm. The all-particle Schroedinger equation is solved in a numerical procedure using the variational principle, Cartesian coordinates, parameterized explicitly correlated Gaussian functions with polynomial prefactors, and the global vector representation. As a result, non-relativistic energy levels and wave functions of few-particle systems can be obtained for various angular momentum, parity, and spin quantum numbers. A stochastic variational optimization of the basis function parameters facilitates the calculation of accurate energies and wave functions for the ground and some excited rotational-(vibrational-)electronic states of H{sub 2}{sup +} and H{sub 2}, three bound states of the positronium molecule, Ps{sub 2}, and the ground and two excited states of the {sup 7}Li atom.

Matyus, Edit; Reiher, Markus [Laboratory of Physical Chemistry, ETH Zuerich, Wolfgang-Pauli-Str. 10, CH-8093 Zuerich (Switzerland)

2012-07-14T23:59:59.000Z

263

Physical process Mechanical mechanisms  

E-Print Network [OSTI]

1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F ­ Quadrupoles......shear stress fluctuations ­ High order poles...... phys. interpretation difficult Governing

Berlin,Technische Universität

264

I, Quantum Robot: Quantum Mind control on a Quantum Computer  

E-Print Network [OSTI]

The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be the use of coherent states in brain signals.

Paola Zizzi

2008-12-25T23:59:59.000Z

265

The DFT+Umol method and its application to the adsorption of CO on platinum model clusters  

SciTech Connect (OSTI)

Semi-local DFT approximations are well-known for their difficulty with describing the correct site preference for the adsorption of CO molecules on (111) surfaces of several late transition metals. To address this problem originating from a residual self-interaction in the CO LUMO, we present the DFT+Umol approach which generalizes the empirical DFT+U correction to fragment molecular orbitals. This correction is applied to examine CO adsorption energies at various sites on the (111) facets of cuboctahedral clusters Pt{sub m}(CO){sub 8} (m = 79, 140, 225). The DFT+Umol correction leaves the electronic ground state of metal clusters, in particular their d-band structure, essentially unchanged, affecting almost exclusively the energy of the CO LUMO. As a result, that correction is significantly stronger for complexes at hollow sites, hence increases the propensity for adsorption at top sites. We also analyze competing edge effects on the (111) facets of the cluster models.

Soini, Thomas M.; Krger, Sven [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany)] [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany); Rsch, Notker, E-mail: roesch@mytum.de [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany) [Department Chemie and Catalysis Research Center, Technische Universitt Mnchen, 85747 Garching (Germany); Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, No. 16-16 Connexis, Singapore 138632 (Singapore)

2014-05-07T23:59:59.000Z

266

The many-body problem A solution: DFT HK theorems KS scheme Summary Key concepts in Density Functional Theory (I)  

E-Print Network [OSTI]

's University, Belfast Key concepts in Density Functional Theory (I) Silvana Botti #12;The many-body problem concepts in Density Functional Theory (I) Silvana Botti #12;The many-body problem A solution: DFT HK theorems KS scheme Summary Outline 1 The many-body problem 2 A solution: Density Functional Theory 3

Botti, Silvana

267

Consistent Quantum Reasoning  

E-Print Network [OSTI]

Precise rules are developed in order to formalize the reasoning processes involved in standard non-relativistic quantum mechanics, with the help of analogies from classical physics. A classical or quantum description of a mechanical system involves a {\\it framework}, often chosen implicitly, and a {\\it statement} or assertion about the system which is either true or false within the framework with which it is associated. Quantum descriptions are no less ``objective'' than their classical counterparts, but differ from the latter in the following respects: (i) The framework employs a Hilbert space rather than a classical phase space. (ii) The rules for constructing meaningful statements require that the associated projectors commute with each other and, in the case of time-dependent quantum histories, that consistency conditions be satisfied. (iii) There are incompatible frameworks which cannot be combined, either in constructing descriptions or in making logical inferences about them, even though any one of these frameworks may be used separately for describing a particular physical system. A new type of ``generalized history'' is introduced which extends previous proposals by Omn\\`es, and Gell-Mann and Hartle, and a corresponding consistency condition which does not involve density matrices or single out a direction of time. Applications which illustrate the formalism include: measurements of spin, two-slit diffraction, and the emergence of the classical world from a fully quantum description.

Robert B. Griffiths

1995-05-17T23:59:59.000Z

268

Damped quantum harmonic oscillator  

E-Print Network [OSTI]

In the framework of the Lindblad theory for open quantum systems the damping of the harmonic oscillator is studied. A generalization of the fundamental constraints on quantum mechanical diffusion coefficients which appear in the master equation for the damped quantum oscillator is presented; the Schr\\"odinger and Heisenberg representations of the Lindblad equation are given explicitly. On the basis of these representations it is shown that various master equations for the damped quantum oscillator used in the literature are particular cases of the Lindblad equation and that the majority of these equations are not satisfying the constraints on quantum mechanical diffusion coefficients. Analytical expressions for the first two moments of coordinate and momentum are also obtained by using the characteristic function of the Lindblad master equation. The master equation is transformed into Fokker-Planck equations for quasiprobability distributions. A comparative study is made for the Glauber $P$ representation, the antinormal ordering $Q$ representation and the Wigner $W$ representation. It is proven that the variances for the damped harmonic oscillator found with these representations are the same. By solving the Fokker-Planck equations in the steady state, it is shown that the quasiprobability distributions are two-dimensional Gaussians with widths determined by the diffusion coefficients. The density matrix is represented via a generating function, which is obtained by solving a time-dependent linear partial differential equation derived from the master equation. Illustrative examples for specific initial conditions of the density matrix are provided.

A. Isar; A. Sandulescu

2006-02-17T23:59:59.000Z

269

Exploring the interaction between lithium ion and defective graphene surface using dispersion corrected DFT studies  

SciTech Connect (OSTI)

To analyze the lithium ion interaction with realistic graphene surfaces, we carried out dispersion corrected DFT-D3 studies on graphene with common point defects and chemisorbed oxygen containing functional groups along with defect free graphene surface. Our study reveals that, the interaction between lithium ion (Li+) and graphene is mainly through the delocalized ? electron of pure graphene layer. However, the oxygen containing functional groups pose high adsorption energy for lithium ion due to the Li-O ionic bond formation. Similarly, the point defect groups interact with lithium ion through possible carbon dangling bonds and/or cation-? type interactions. Overall these defect sites render a preferential site for lithium ions compared with pure graphene layer. Based on these findings, the role of graphene surface defects in lithium battery performance were discussed.

Vijayakumar, M.; Hu, Jian Z.

2013-10-15T23:59:59.000Z

270

An Efficient Arithmetic Sum-of-Product (SOP) based Multiplication Approach for FIR Filters and DFT  

E-Print Network [OSTI]

, the output of a FIR filter is the weighted sum of the current value and a finite number of previous values of the input. An important property of FIR filters is their inherent stability due to the lack of feedback from the output. Y (n) = N?1 ? l=0 x(n... . . . . . . +++ . . . . . .+ + + + MCM z?1 z?1 z?1 z?1 a) Direct Form Realization z?1 z?1 z?1 z?1 b) Transposed Direct Form Realization c0 c1 c2 c3 cN?1 cN?3cN?1 c0cN?2 x(n) x(n) SOP Y (n) Y (n) cN?4 Fig. I.1. Implementation of DFT The previous approaches for solving...

Kumar, Rajeev

2013-04-24T23:59:59.000Z

271

First principles DFT investigation of yttrium-doped graphene: Electronic structure and hydrogen storage  

SciTech Connect (OSTI)

The electronic structure and hydrogen storage capability of Yttrium-doped grapheme has been theoretically investigated using first principles density functional theory (DFT). Yttrium atom prefers the hollow site of the hexagonal ring with a binding energy of 1.40 eV. Doping by Y makes the system metallic and magnetic with a magnetic moment of 2.11 ?{sub B}. Y decorated graphene can adsorb up to four hydrogen molecules with an average binding energy of 0.415 eV. All the hydrogen atoms are physisorbed with an average desorption temperature of 530.44 K. The Y atoms can be placed only in alternate hexagons, which imply a wt% of 6.17, close to the DoE criterion for hydrogen storage materials. Thus, this system is potential hydrogen storage medium with 100% recycling capability.

Desnavi, Sameerah, E-mail: sameerah-desnavi@zhcet.ac.in [Department of Electronic Engineering, ZHCET, Aligarh Muslim University, Aligarh-202002 (India); Chakraborty, Brahmananda; Ramaniah, Lavanya M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

2014-04-24T23:59:59.000Z

272

Quantum Cloning Machines and the Applications  

E-Print Network [OSTI]

No-cloning theorem is fundamental for quantum mechanics and for quantum information science that states an unknown quantum state cannot be cloned perfectly. However, we can try to clone a quantum state approximately with the optimal fidelity, or instead, we can try to clone it perfectly with the largest probability. Thus various quantum cloning machines have been designed for different quantum information protocols. Specifically, quantum cloning machines can be designed to analyze the security of quantum key distribution protocols such as BB84 protocol, six-state protocol, B92 protocol and their generalizations. Some well-known quantum cloning machines include universal quantum cloning machine, phase-covariant cloning machine, the asymmetric quantum cloning machine and the probabilistic quantum cloning machine etc. In the past years, much progress has been made in studying quantum cloning machines and their applications and implementations, both theoretically and experimentally. In this review, we will give a complete description of those important developments about quantum cloning and some related topics. On the other hand, this review is self-consistent, and in particular, we try to present some detailed formulations so that further study can be taken based on those results.

Heng Fan; Yi-Nan Wang; Li Jing; Jie-Dong Yue; Han-Duo Shi; Yong-Liang Zhang; Liang-Zhu Mu

2014-08-02T23:59:59.000Z

273

A multiplexed quantum memory  

Science Journals Connector (OSTI)

A quantum repeater is a system for long-distance quantum communication that employs quantum memory elements to mitigate optical fiber transmission losses. The multiplexed quantum...

Lan, S -Y; Radnaev, A G; Collins, O A; Matsukevich, D N; Kennedy, T A; Kuzmich, A

2009-01-01T23:59:59.000Z

274

Quantum stochastic walks: A generalization of classical random walks and quantum walks  

SciTech Connect (OSTI)

We introduce the quantum stochastic walk (QSW), which determines the evolution of a generalized quantum-mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical, and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases but also includes more general probability distributions. As an example, we study the QSW on a line and the glued tree of depth three to observe the behavior of the QW-to-CRW transition.

Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan; Whitfield, James D.

2010-01-01T23:59:59.000Z

275

Quantum stochastic walks: A generalization of classical random walks and quantum walks  

SciTech Connect (OSTI)

We introduce the quantum stochastic walk (QSW), which determines the evolution of a generalized quantum-mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical, and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases but also includes more general probability distributions. As an example, we study the QSW on a line and the glued tree of depth three to observe the behavior of the QW-to-CRW transition.

Whitfield, James D.; Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan [Department of Chemistry and Chemical Biology and Center for Excitonics, Harvard University, Cambridge, Massachusetts 02138 (United States)

2010-02-15T23:59:59.000Z

276

Quantum convolutional stabilizer codes  

E-Print Network [OSTI]

and computer scientists such as Charles H. Bennett of the IBM Thomas J. Watson Research Center, Paul A. Benio of Argonne National Laboratory in Illinois, David Deutsch of the University of Oxford, and Richard P. Feynman of California Institute of Technology... are inherently quantum mechanical in nature, not classical. Feynman was among the rst to attempt to provide an answer to this question by producing an abstract model in 1982 that showed how a quantum system could be used to do computations. Later, in 1985...

Chinthamani, Neelima

2004-09-30T23:59:59.000Z

277

Information and quantum nonseparability  

Science Journals Connector (OSTI)

An information-theoretic inequality analogous to the well-known result of Bell [Physics 1, 195 (1964)] is formulated using the concept of information distance. This inequality, like Bells, is true for all local-hidden-variable theories, but not for quantum mechanics. The metric space structure of this new inequality suggests a reformulation of familiar Bell inequalities in terms of a covariance distance. Quantum nonseparability can be demonstrated through violations of these inequalities even in cases where the correlation between two systems is extremely weak. The connection between nonseparability and complementarity is also briefly discussed in this paper.

B. W. Schumacher

1991-12-01T23:59:59.000Z

278

Quantum thermodynamic cooling cycle  

E-Print Network [OSTI]

The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

Palao, J P; Gordon, J M; Palao, Jose P.; Kosloff, Ronnie; Gordon, Jeffrey M.

2001-01-01T23:59:59.000Z

279

Quantum thermodynamic cooling cycle  

E-Print Network [OSTI]

The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

Jose P. Palao; Ronnie Kosloff; Jeffrey M. Gordon

2001-06-08T23:59:59.000Z

280

Characterizing quantum coherence  

Science Journals Connector (OSTI)

For a system with canonical variables x and p, [x,p]=i?, we associate with each density operator ? an x coherence ?x and a p coherence ?p which specify, respectively, the characteristic distance and momentum range over which the underlying quantum-mechanical nature of the ensemble cannot be neglected. These coherences are less than or equal to the associated uncertainties ?x??x, ?p??p; so the ratios cx??x/?x, cp??p/?p give measures of the quantum character of the ensemble with respect to x and p. Examples are presented.

J. E. Sipe and N. Arkani-Hamed

1992-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

The Quantum Mellin transform  

E-Print Network [OSTI]

We uncover a new type of unitary operation for quantum mechanics on the half-line which yields a transformation to ``Hyperbolic phase space''. We show that this new unitary change of basis from the position x on the half line to the Hyperbolic momentum $p_\\eta$, transforms the wavefunction via a Mellin transform on to the critial line $s=1/2-ip_\\eta$. We utilise this new transform to find quantum wavefunctions whose Hyperbolic momentum representation approximate a class of higher transcendental functions, and in particular, approximate the Riemann Zeta function. We finally give possible physical realisations to perform an indirect measurement of the Hyperbolic momentum of a quantum system on the half-line.

J. Twamley; G. J. Milburn

2007-02-12T23:59:59.000Z

282

E-Print Network 3.0 - atom based quantum Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Summary: . Nanostructure electronics 3. Atomic chain electronics 4. Quantum optoelectronics (Web page: http... , mechanically simple . smarter (autonomous) . New...

283

Quantum artificial neural networks with applications  

Science Journals Connector (OSTI)

Abstract Since simulations of classical artificial neural networks (CANNs) run on classical computers, the massive parallel processing speed advantage of a neural network is lost. A quantum computer is a computation device that makes direct use of quantummechanical phenomena while large-scale quantum computers will be able to solve certain problems much quicker than any classical computer using the best currently known algorithms. Combining the advantages of quantum computers and the idea of CANNs, we propose in this paper a new type of neural networks, named a quantum artificial neural network (QANN), which is presented as a system of interconnected quantum neurons which can compute quantum states from input-quantum states by feeding information through the network and can be simulated on quantum computers. To show the ability of approximation of a QANN, we prove a universal approximation theorem (UAT) which reads every continuous mapping that transforms n quantum states as a non-normalized quantum state can be uniformly approximated by a QANN. The UAT implies that \\{QANNs\\} would suggest a potential computing tool for dealing with quantum information. For instance, we prove that the state of a quantum system driven by a time-dependent Hamiltonian can be approximated uniformly by a QANN. This provides a possible way for finding approximate solution to a Schrdinger equation with a time-dependent Hamiltonian.

Huaixin Cao; Feilong Cao; Dianhui Wang

2015-01-01T23:59:59.000Z

284

Quantum metrology and its application in biology  

E-Print Network [OSTI]

Quantum metrology provides a route to overcome practical limits in sensing devices. It holds particular relevance in biology, where sensitivity and resolution constraints restrict applications both in fundamental biophysics and in medicine. Here, we review quantum metrology from this biological context. The understanding of quantum mechanics developed over the past century has already enabled important applications in biology, including positron emission tomography (PET) with entangled photons, magnetic resonance imaging (MRI) using nuclear magnetic resonance, and bio-magnetic imaging with superconducting quantum interference devices (SQUIDs). With the birth of quantum information science came the realization that an even greater range of applications arise from the ability to not just understand, but to engineer coherence and correlations in systems at the quantum level. In quantum metrology, quantum coherence and quantum correlations are engineered to enable new approaches to sensing. This review focusses specifically on optical quantum metrology, where states of light that exhibit non-classical photon correlations are used to overcome practical and fundamental constraints, such as the shot-noise and diffraction limits. Recent experiments have demonstrated quantum enhanced sensing of biological systems, and established the potential for quantum metrology in biophysical research. These experiments have achieved capabilities that may be of significant practical benefit, including enhanced sensitivity and resolution, immunity to imaging artifacts, and characterisation of the biological response to light at the single-photon level. New quantum measurement techniques offer even greater promise, raising the prospect for improved multi-photon microscopy and magnetic imaging, among many other possible applications.

Michael A. Taylor; Warwick P. Bowen

2014-09-03T23:59:59.000Z

285

Quantum friction  

E-Print Network [OSTI]

The Brownian motion of a light quantum particle in a heavy classical gas is theoretically described and a new expression for the friction coefficient is obtained for arbitrary temperature. At zero temperature it equals to the de Broglie momentum of the mean free path divided by the mean free path. Alternatively, the corresponding mobility of the quantum particle in the classical gas is equal to the square of the mean free path divided by the Planck constant. The Brownian motion of a quantum particle in a quantum environment is also discussed.

R. Tsekov

2012-03-12T23:59:59.000Z

286

Experimental entanglement-assisted quantum delayed-choice experiment  

E-Print Network [OSTI]

The puzzling properties of quantum mechanics, wave-particle duality, entanglement and superposition, were dissected experimentally at past decades. However, hidden-variable (HV) models, based on three classical assumptions of wave-particle objectivity, determinism and independence, strive to explain or even defeat them. The development of quantum technologies enabled us to test experimentally the predictions of quantum mechanics and HV theories. Here, we report an experimental demonstration of an entanglement-assisted quantum delayed-choice scheme using a liquid nuclear magnetic resonance quantum information processor. This scheme we realized is based on the recently proposed scheme [Nat. Comms. 5:4997(2014)], which gave different results for quantum mechanics and HV theories. In our experiments, the intensities and the visibilities of the interference are in consistent the theoretical prediction of quantum mechanics. The results imply that a contradiction is appearing when all three assumptions of HV models are combined, though any two of the above assumptions are compatible with it.

Tao Xin; Hang Li; Bi-Xue Wang; Gui-Lu Long

2014-11-30T23:59:59.000Z

287

Surface Area and Microporosity of a Pillared Interlayered Clay (PILC) from a Hybrid Density Functional Theory (DFT) Method  

Science Journals Connector (OSTI)

Surface Area and Microporosity of a Pillared Interlayered Clay (PILC) from a Hybrid Density Functional Theory (DFT) Method ... Using these models and the experimental isotherm data, the integral equation of adsorption was inverted by a regularization method to yield the micropore and mesopore size distribution of a pillared interlayered clay (PILC). ... In this paper we show how such a deconvolution method can be used for estimating the pore size distribution of a pillared interlayered clay (PILC). ...

James P. Olivier; Mario L. Occelli

2000-12-23T23:59:59.000Z

288

Electronic structure and excitations in oxygen deficient CeO2?? from DFT calculations  

Science Journals Connector (OSTI)

The electronic structures of supercells of CeO2?? have been calculated within the density functional theory (DFT). The equilibrium properties such as lattice constants, bulk moduli, and magnetic moments are well reproduced by the generalized gradient approximation (GGA). Electronic excitations are simulated by robust total-energy calculations for constrained states with atomic core holes or valence holes. Pristine ceria CeO2 is found to be a nonmagnetic insulator with magnetism setting in as soon as oxygens are removed from the structure. In the ground state of defective ceria, the Ce-f majority band resides near the Fermi level but appears at about 2eV below the Fermi level in photoemission spectroscopy experiments due to final-state effects. We also tested our computational method by calculating threshold energies in Ce-M5 and O-K x-ray absorption spectroscopy and comparing theoretical predictions with the corresponding measurements. Our result that f electrons reside near the Fermi level in the ground state of oxygen-deficient ceria is crucial for understanding the catalytic properties of CeO2 and related materials.

T. Jarlborg; B. Barbiellini; C. Lane; Yung Jui Wang; R. S. Markiewicz; Zhi Liu; Zahid Hussain; A. Bansil

2014-04-01T23:59:59.000Z

289

Transport and Dissipation in Quantum Pumps  

E-Print Network [OSTI]

This paper is about adiabatic transport in quantum pumps. The notion of ``energy shift'', a self-adjoint operator dual to the Wigner time delay, plays a role in our approach: It determines the current, the dissipation, the noise and the entropy currents in quantum pumps. We discuss the geometric and topological content of adiabatic transport and show that the mechanism of Thouless and Niu for quantized transport via Chern numbers cannot be realized in quantum pumps where Chern numbers necessarily vanish.

J. E. Avron; A. Elgart; G. M. Graf; L. Sadun

2003-05-23T23:59:59.000Z

290

Information and noise in quantum measurement  

Science Journals Connector (OSTI)

Even though measurement results obtained in the real world are generally both noisy and continuous, quantum measurement theory tends to emphasize the ideal limit of perfect precision and quantized measurement results. In this article, a more general concept of noisy measurements is applied to investigate the role of quantum noise in the measurement process. In particular, it is shown that the effects of quantum noise can be separated from the effects of information obtained in the measurement. However, quantum noise is required to cover up negative probabilities arising as the quantum limit is approached. These negative probabilities represent fundamental quantum-mechanical correlations between the measured variable and the variables affected by quantum noise.

Holger F. Hofmann

2000-07-06T23:59:59.000Z

291

Quantum optical technologies for metrology, sensing and imaging  

E-Print Network [OSTI]

Over the past 20 years, bright sources of entangled photons have led to a renaissance in quantum optical interferometry. Optical interferometry has been used to test the foundations of quantum mechanics and implement some of the novel ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and quantum metrology. In this paper, we focus on the new ways that have been developed to exploit quantum optical entanglement in quantum metrology to beat the shot-noise limit, which can be used, e.g., in fiber optical gyroscopes and in sensors for biological or chemical targets. We also discuss how this entanglement can be used to beat the Rayleigh diffraction limit in imaging systems such as in LIDAR and optical lithography.

Jonathan P. Dowling; Kaushik P. Seshadreesan

2014-12-24T23:59:59.000Z

292

High-fidelity quantum memory using nitrogen-vacancy center ensemble for hybrid quantum computation  

SciTech Connect (OSTI)

We study a hybrid quantum computing system using a nitrogen-vacancy center ensemble (NVE) as quantum memory, a current-biased Josephson junction (CBJJ) superconducting qubit fabricated in a transmission line resonator (TLR) as the quantum computing processor, and the microwave photons in TLR as the quantum data bus. The storage process is seriously treated by considering all kinds of decoherence mechanisms. Such a hybrid quantum device can also be used to create multiqubit W states of NVEs through a common CBJJ. The experimental feasibility is achieved using currently available technology.

Yang, W. L.; Feng, M. [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, and Wuhan National Laboratory for Optoelectronics, Wuhan 430071 (China); Yin, Z. Q. [Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026 (China); Hu, Y. [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Du, J. F. [Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026 (China)

2011-07-15T23:59:59.000Z

293

Stochastic Geometry of Classical and Quantum Ising Models  

E-Print Network [OSTI]

Stochastic Geometry of Classical and Quantum Ising Models Dmitry Ioffe Faculty of Industrial) and to the random current (RC) representation of classical and quantum Ising models via path integrals. No background in quantum statistical mechanics was assumed. In Section 1 familiar classical Ising models

294

Quantum Money from Hidden Subspaces Scott Aaronson # Paul Christiano +  

E-Print Network [OSTI]

Quantum Money from Hidden Subspaces Scott Aaronson # Paul Christiano + Abstract Forty years ago, Wiesner pointed out that quantum mechanics raises the striking possibility of money that cannot be counterfeited according to the laws of physics. We propose the first quantum money scheme that is (1) public

Aaronson, Scott

295

Multiple-user quantum optical communication  

E-Print Network [OSTI]

A fundamental understanding of the information carrying capacity of optical channels requires the signal and physical channel to be modeled quantum mechanically. This thesis considers the problems of distributing multi-party ...

Yen, Brent J., 1977-

2005-01-01T23:59:59.000Z

296

Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT  

SciTech Connect (OSTI)

We have investigated the description of excited state relaxation in naked and hydrated TiO2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be the inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. Finally, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO2 nanoparticles is predicted to be associated with a large Stokes shift.

Berardo, Enrico; Hu, Hanshi; van Dam, Hubertus JJ; Shevlin, S. A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

2014-10-30T23:59:59.000Z

297

Quantum Chromodynamics  

Science Journals Connector (OSTI)

The theory of the strong interaction of elementary particles, Quantum Chromodynamics (QCD), is a non-abelian gauge theory with SU(3) as gauge group. The degrees of freedom corresponding to this SU(3) are called c...

Prof. Dr. rer. nat. Manfred Bhm

2001-01-01T23:59:59.000Z

298

Vibration-enhanced quantum transport  

E-Print Network [OSTI]

In this paper, we study the role of collective vibrational motion in the phenomenon of electronic energy transfer (EET) along a chain of coupled electronic dipoles with varying excitation frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduces correlations in the energy gap fluctuations which cause coherent EET. Inspired by these results, we present a simple model in which a driven nanomechanical resonator mode modulates the excitation energy of coupled quantum dots and find that this can indeed lead to an enhancement in the transport of excitations across the quantum network. Disorder of the on-site energies is a key requirement for this to occur. We also show that in this solid state system phase information is partially retained in the transfer process, as experimentally demonstrated in conjugated polymer samples. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.

F. L. Semio; K. Furuya; G. J. Milburn

2009-09-09T23:59:59.000Z

299

Quantum potential energy as concealed motion  

E-Print Network [OSTI]

It is known that the Schroedinger equation may be derived from a hydrodynamic model in which the Lagrangian position coordinates of a continuum of particles represent the quantum state. Using Routh\\s method of ignorable coordinates it is shown that the quantum potential energy of particle interaction that represents quantum effects in this model may be regarded as the kinetic energy of additional concealed freedoms. The method brings an alternative perspective to Planck\\s constant, which plays the role of a hidden variable, and to the canonical quantization procedure, since what is termed kinetic energy in quantum mechanics may be regarded literally as energy due to motion.

Peter Holland

2014-11-13T23:59:59.000Z

300

Quantum phase gate for optical qubits with cavity quantum optomechanics  

E-Print Network [OSTI]

We show that a cavity optomechanical system formed by a mechanical resonator simultaneously coupled to two modes of an optical cavity can be used for the implementation of quantum phase gate between optical qubits associated with the two intracavity modes. The scheme is realizable for sufficiently strong single-photon optomechanical coupling in the resolved sideband regime, and is robust against cavity losses.

Muhammad Asjad; Paolo Tombesi; David Vitali

2015-01-16T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Quantum corrections to classical evaluation of nonadiabatic transition rates  

SciTech Connect (OSTI)

A recently developed quantum correction approach is applied to evaluating the nonadiabatic quantum-mechanical transition rate between Born-Oppenheimer states of a subsystem embedded in a thermal bath of harmonic oscillators. In the first-order perturbation theory, the nonadiabatic rate can be expressed in terms of a quantum-mechanical correlation function, which can be estimated directly from classical data. Application to a popular spin-boson model shows that our results are in excellent agreement with the exact quantum-mechanical results.

Kim, Hyojoon; Rossky, Peter J. [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada); Institute for Theoretical Chemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712 (United States)

2006-08-14T23:59:59.000Z

302

A Polarizable QM/MM Explicit Solvent Model for Computational Electrochemistry in Water  

E-Print Network [OSTI]

We present a quantum mechanical/molecular mechanical (QM/MM) explicit solvent model for the computation of standard reduction potentials E[subscript 0]. The QM/MM model uses density functional theory (DFT) to model the ...

Wang, Lee-Ping

303

Mesoscopic Fractional Quantum in Soft Matter  

E-Print Network [OSTI]

Soft matter (e.g., biomaterials, polymers, sediments, oil, emulsions) has become an important bridge between physics and diverse disciplines. Its fundamental physical mechanism, however, is largely obscure. This study made the first attempt to connect fractional Schrodinger equation and soft matter physics under a consistent framework from empirical power scaling to phenomenological kinetics and macromechanics to mesoscopic quantum mechanics. The original contributions are the fractional quantum relationships, which show Levy statistics and fractional Brownian motion are essentially related to momentum and energy, respectively. The fractional quantum underlies fractal mesostructures and many-body interactions of macromolecules in soft matter and is experimentally testable.

W Chen

2005-05-09T23:59:59.000Z

304

Classical versus quantum coherence  

Science Journals Connector (OSTI)

...M. Stoneham Classical versus quantum coherence P. T. Greenland Department of Physics...nanostructures| Classical versus quantum coherence. | Quantum dots are structures engineered...2002.1134 Classical versus quantum coherence By P. T. Greenland Department of Physics...

2003-01-01T23:59:59.000Z

305

A New Ontological View of the Quantum Measurement Problem  

E-Print Network [OSTI]

A new ontological view of the quantum measurement processes is given, which has bearings on many broader issues in the foundations of quantum mechanics as well. In this scenario a quantum measurement is a non-equilibrium phase transition in a ``resonant cavity'' formed by the entire physical universe including all of its material and energy content. A quantum measurement involves the energy and matter exchange among not only the system being measured and the measuring apparatus but also the global environment of the universe resonant cavity, which together constrain the nature of the phase transition. Strict realism, including strict energy and angular momentum conservation, is recovered in this view of the quantum measurement process beyond the limit set by the uncertainty relations, which are themselves derived from the exact commutation relations for quantum conjugate variables. Both the amplitude and the phase of the quantum mechanical wavefunction acquire substantial meanings in the new ontology, and the probabilistic element is removed from the foundations of quantum mechanics, its apparent presence in the quantum measurement being solely a result of the sensitive dependence on initial/boundary conditions of the phase transitions of a many degree-of-freedom system which is effectively the whole universe. Vacuum fluctuations are viewed as the ``left over'' fluctuations after forming the whole numbers of nonequilibrium resonant modes in the universe cavity. This new view on the quantum processes helps to clarify many puzzles in the foundations of quantum mechanics.

Xiaolei Zhang

2005-06-13T23:59:59.000Z

306

Macroscopic quantum tunnelling in a current biased Josephson junction  

SciTech Connect (OSTI)

We discuss in this work an attempt to answer experimentally the question: do macroscopic variables obey quantum mechanics. More precisely, this experiment deals with the question of quantum-mechanical tunnelling of a macroscopic variable, a subject related to the famous Schrodinger's cat problem in the theory of measurement.

Martinis, J.M.; Devoret, M.H.; Clarke, J.; Urbina, C.

1984-11-01T23:59:59.000Z

307

Quantum Money from Hidden Subspaces  

E-Print Network [OSTI]

Forty years ago, Wiesner pointed out that quantum mechanics raises the striking possibility of money that cannot be counterfeited according to the laws of physics. We propose the first quantum money scheme that is (1) public-key, meaning that anyone can verify a banknote as genuine, not only the bank that printed it, and (2) cryptographically secure, under a "classical" hardness assumption that has nothing to do with quantum money. Our scheme is based on hidden subspaces, encoded as the zero-sets of random multivariate polynomials. A main technical advance is to show that the "black-box" version of our scheme, where the polynomials are replaced by classical oracles, is unconditionally secure. Previously, such a result had only been known relative to a quantum oracle (and even there, the proof was never published). Even in Wiesner's original setting -- quantum money that can only be verified by the bank -- we are able to use our techniques to patch a major security hole in Wiesner's scheme. We give the first private-key quantum money scheme that allows unlimited verifications and that remains unconditionally secure, even if the counterfeiter can interact adaptively with the bank. Our money scheme is simpler than previous public-key quantum money schemes, including a knot-based scheme of Farhi et al. The verifier needs to perform only two tests, one in the standard basis and one in the Hadamard basis -- matching the original intuition for quantum money, based on the existence of complementary observables. Our security proofs use a new variant of Ambainis's quantum adversary method, and several other tools that might be of independent interest.

Scott Aaronson; Paul Christiano

2012-09-17T23:59:59.000Z

308

QKarD Quantum Smart Card  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

QKarD Quantum Smart Card QKarD Quantum Smart Card QKarD Quantum Smart Card Los Alamos National Laboratory (LANL) scientists have developed a revolutionary technology entitled "QKarD" that implements the quantum mechanical laws of physics rather than complex mathematical problems to encrypt information. July 11, 2013 QKarD Quantum Smart Card Available for thumbnail of Feynman Center (505) 665-9090 Email QKarD Quantum Smart Card Applications: Telecommunications: cell /smartphone; multi-party secure phone calls; videoconferencing; Voice over IP (VoIP) Banking and financial transactions:ATM, debit / credit card and e-Commerce e-Business; e-gaming; e-books; e-music; e-movies; e-gambling Wireless internet Electronic voting Facility and vehicle access Information exchange for government/defense

309

Exploring topological phases with quantum walks  

SciTech Connect (OSTI)

The quantum walk was originally proposed as a quantum-mechanical analog of the classical random walk, and has since become a powerful tool in quantum information science. In this paper, we show that discrete-time quantum walks provide a versatile platform for studying topological phases, which are currently the subject of intense theoretical and experimental investigations. In particular, we demonstrate that recent experimental realizations of quantum walks with cold atoms, photons, and ions simulate a nontrivial one-dimensional topological phase. With simple modifications, the quantum walk can be engineered to realize all of the topological phases, which have been classified in one and two dimensions. We further discuss the existence of robust edge modes at phase boundaries, which provide experimental signatures for the nontrivial topological character of the system.

Kitagawa, Takuya; Rudner, Mark S.; Berg, Erez; Demler, Eugene [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

2010-09-15T23:59:59.000Z

310

Quantum Structures of the Hydrogen Atom  

E-Print Network [OSTI]

Modern quantum theory introduces quantum structures (decompositions into subsystems) as a new discourse that is not fully comparable with the classical-physics counterpart. To this end, so-called Entanglement Relativity appears as a corollary of the universally valid quantum mechanics that can provide for a deeper and more elaborate description of the composite quantum systems. In this paper we employ this new concept to describe the hydrogen atom. We offer a consistent picture of the hydrogen atom as an open quantum system that naturally answers the following important questions: (a) how do the so called "quantum jumps" in atomic excitation and de-excitation occur? and (b) why does the classically and seemingly artificial "center-of-mass + relative degrees of freedom" structure appear as the primarily operable form in most of the experimental reality of atoms?

J. Jeknic-Dugic; M. Dugic; A. Francom; M. Arsenijevic

2014-05-28T23:59:59.000Z

311

Hybrid DFT study on the gas-phase SN2 reactions at neutral oxygen  

Science Journals Connector (OSTI)

The hybrid DFT method MPW1K, in conjunction with 6-31+G(d,p) basis sets, has been examined for the gas-phase reactions, Y?+HOX (Y, X=F, Cl, Br, I). Comparison of the results with the high-level G2(+) theory indicates that MPW1K/6-31+G(d,p) approach performs well in describing the potential energy surface for the identity SN2 reactions X?+HOX?HOX+X? (X=Cl, Br, I). The corresponding non-identity reactions (Y?X, Y, X=Cl, Br, I), are exothermic if the nucleophile is the heavier halide, in contrast to the corresponding reactions at carbon. The fluorine behaves different from the other halogens. The reactions Y?+HOF (Y=F, Cl, Br, I) are predicted to form the energetically favorable products YO?+HF with a large driving force(?H=?48.6, ?47.2, ?56.5, ?69.0kJ/mol for Y=F, Cl, Br, I, respectively) and lower reaction enthalpies than the corresponding SN2 reactions by about 60kJ/mol. Central barrier heights (?HYX?) for SN2 reactions in the exothermic directions vary from 52.5kJ/mol for Y=I, X=Br up to 76.6kJ/mol for Y=Br, X=Cl. Overall barriers (?HYXb) for reactions in the exothermic direction are all negative (varying from ?13.8kJ/mol for Y=I, X=Br to ?5.2kJ/mol for Y=Br, X=Cl). Complexation energies (?Hcomp) of the ionmolecule complexes Y??HOX vary from 66.3kJ/mol for Y=I, X=Br to 95.5kJ/mol for Y=Cl, X=Br. The central barrier heights ?HYX? and ?HXY? correlate well with the degree of the O?X and O?Y bond elongation in the transition structures. Both central and overall barriers can be interpreted with the aid of Marcus equation.

Yi Ren; Joel L. Wolk; Shmaryahu Hoz

2003-01-01T23:59:59.000Z

312

Artificial Neural Network Methods in Quantum Mechanics  

E-Print Network [OSTI]

In a previous article we have shown how one can employ Artificial Neural Networks (ANNs) in order to solve non-homogeneous ordinary and partial differential equations. In the present work we consider the solution of eigenvalue problems for differential and integrodifferential operators, using ANNs. We start by considering the Schr\\"odinger equation for the Morse potential that has an analytically known solution, to test the accuracy of the method. We then proceed with the Schr\\"odinger and the Dirac equations for a muonic atom, as well as with a non-local Schr\\"odinger integrodifferential equation that models the $n+\\alpha$ system in the framework of the resonating group method. In two dimensions we consider the well studied Henon-Heiles Hamiltonian and in three dimensions the model problem of three coupled anharmonic oscillators. The method in all of the treated cases proved to be highly accurate, robust and efficient. Hence it is a promising tool for tackling problems of higher complexity and dimensionality.

I. E. Lagaris; A. Likas; D. I. Fotiadis

1997-05-15T23:59:59.000Z

313

From Quantum Mechanics to String Theory  

E-Print Network [OSTI]

at Midway station send signals to both at the same time, so that Alice receives hers when she reaches Europa

314

THEORY OF QUANTUM-MECHANICAL DESCRIPTION  

Science Journals Connector (OSTI)

...classes for all scientific methodology has repeatedly been...rules of the operator calculus one can assign a probability...by maximizing S with subsidiary conditions. The conditions...of the conventional methodology of physical science...

Walter M. Elsasser

1968-01-01T23:59:59.000Z

315

From Quantum Mechanics to String Theory  

E-Print Network [OSTI]

's Constant Newton's constant G appears in the universal law of gravitation: It determines the strength potential energy that we see as mass a spontaneously broken symmetry is a symmetry of the laws of nature. An object of mass m in a gravitational field g feels a force of F = mg This is similar to electromagnetism

316

Mechanical quantum resonators A. N. Cleland  

E-Print Network [OSTI]

. The computational qubits are eigenstates of large-area, current-biased Josephson junctions. Two or more qubits of the qubits. The integrated system is analogous to one or more few-level atoms (the Josephson junction qubits in a Josephson junction can be passed to the nanomechanical resonator and stored there, and then can be passed

Geller, Michael R.

317

Uncertainty in quantum mechanics: faith or fantasy?  

Science Journals Connector (OSTI)

...experiments in 2 encounters mirrors or beam splitters and when...is proposed to put a tiny mirror-a cube of about 1mum in...Mach-Zehnder interferometer): with mirrors at C and D, and another beam...1975Scalar production in Schwarzschild and Rindler metricsJ. Phys...

2011-01-01T23:59:59.000Z

318

From Quantum Mechanics to String Theory  

E-Print Network [OSTI]

electric fields to accelerate the particles and magnetic fields to control their directions detectors particles, the nuclear force) neutrinos (beta decay, conservation laws, particle stability) Thursday, May 7 these states exist, but they are all filled. Redefine the vacuum as this situation: define this as a zero

319

From Quantum Mechanics to String Theory  

E-Print Network [OSTI]

electron/positron pairs in the vacuum shield electromagnetic charges, making them seem smaller than for a while it looked like we were close to a complete picture, with just the electromagnetic and nuclear forces, and the particles from last time In the 1950s and 60s accelerator and cosmic ray experiments

320

AMEAerospace & Mechanical  

E-Print Network [OSTI]

AMEAerospace & Mechanical Engineering #12;Aerospace and Mechanical Engineers design complex mechanical, thermal, fluidic, acousti- cal, optical, and electronic systems, with char- acteristic sizes space. Aerospace and Mechanical Engineering (AME) students conduct basic and applied research within

Wang, Hai

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Stochastic quantization weakening and quantum entanglement decoherence  

E-Print Network [OSTI]

The paper investigates the non-local property of quantum mechanics in the quantum hydrodynamic analogy (QHA) given by Madelung. The role of the quantum potential in generating the non-local dynamics of quantum mechanics is analyzed. The work shows how in presence of noise the non-local properties as well as the quantization of the action are perturbed. The resulting stochastic QHA dynamics much depend by the strength of the interaction: Strongly bounded systems (such as linear ones) lead to quantum entangled stochastic behavior, while weakly bounded ones may be not able to maintain the quantum superposition of states on large distances and may loose their macro-scale quantum coherence acquiring the classical stochastic evolution . The work shows that in the frame of the stochastic approach it is possible to have freedom between quantum weakly bounded systems. The stochastic QHA model shows that the wave-function collapse to an eigenstates (deriving by interaction of a quantum microscopic system with a classical (macroscopic) one) can be described by the model itself as a kinetic quantum (relaxation) process to a stationary state. Since the time of the wave function decay to the eigenstate represents the minimum duration time of a measurement, the minimum uncertainty principle is shown to be compatible with the relativistic postulate about the light speed as the maximum velocity of transmission of interaction. About this topic, the paper shows that the Lorenz invariance of the relativistic quantum potential (coming from the Dirac equation) enforces the hypothesis that the superluminal transmission of information are not present in measurements on quantum entangled state.

Piero Chiarelli

2014-08-19T23:59:59.000Z

322

Quantum Non-Objectivity from Performativity of Quantum Phenomena  

E-Print Network [OSTI]

We analyze the logical foundations of quantum mechanics (QM) by stressing non-objectivity of quantum observables which is a consequence of the absence of logical atoms in QM. We argue that the matter of quantum non-objectivity is that, on the one hand, the formalism of QM constructed as a mathematical theory is self-consistent, but, on the other hand, quantum phenomena as results of experimenter's performances are not self-consistent. This self-inconsistency is an effect of that the language of QM differs much from the language of human performances. The first is the language of a mathematical theory which uses some Aristotelian and Russellian assumptions (e.g., the assumption that there are logical atoms). The second language consists of performative propositions which are self-inconsistent only from the viewpoint of conventional mathematical theory, but they satisfy another logic which is non-Aristotelian. Hence, the representation of quantum reality in linguistic terms may be different: from a mathematical theory to a logic of performative propositions. To solve quantum self-inconsistency, we apply the formalism of non-classical self-referent logics.

Andrei Khrennikov; Andrew Schumann

2014-04-04T23:59:59.000Z

323

A Computational Study of the Deacylation Mechanism of Human Butyrylcholinesterase  

Science Journals Connector (OSTI)

To investigate the mechanism of the deacylation reaction in the active site of human butyrylcholinesterase (BuChE), we carried out quantum mechanical (QM) calculations on cluster models of the active site built from a crystallographic structure. The ...

Dimas Surez; Natalia Daz; Juan Fontecilla-Camps; Martin J. Field

2006-05-19T23:59:59.000Z

324

Hybrid DFT Functional-Based Static and Molecular Dynamics Studies of Excess Electron in Liquid Ethylene Carbonate  

SciTech Connect (OSTI)

We applied static and dynamic hybrid functional density functional theory (DFT) calculations to study the interactions of one and two excess electrons with ethylene carbonate (EC) liquid and clusters. Optimal structures of (EC){sub n} and (EC){sup ?}{sub n} clusters devoid of Li{sub +} ions, n?=?16, were obtained. The excess electron was found to be localized on a single EC in all cases, and the EC dimeric radical anion exhibits a reduced barrier associated with the breaking of the ethylene carbonoxygen covalent bond compared to EC{sub ?}. In ab initio molecular dynamics (AIMD) simulations of EC{sub ?} solvated in liquid EC, large fluctuations in the carbonyl carbonoxygen bond lengths were observed. AIMD simulations of a two-electron attack on EC in EC liquid and on Li metal surfaces yielded products similar to those predicted using nonhybrid DFT functionals, except that CO release did not occur for all attempted initial configurations in the liquid state.

Yu, J M; Balbuena, P B; Budzien, J L; Leung, Kevin

2011-01-01T23:59:59.000Z

325

On Quantum Phase Transition. I. Spinless Electrons Strongly Correlated with Ions  

Science Journals Connector (OSTI)

We study a large class F of models of the quantum statistical mechanics...dealing with two types of particles. First the spinless electrons are quantum particles obeying to the Fermi statistics, t...

Alain Messager

2002-02-01T23:59:59.000Z

326

Techniques for noise suppression and robust control in spin-based quantum information processors  

E-Print Network [OSTI]

Processing information quantum mechanically allows the relatively efficient solution of many important problems thought to be intractable on a classical computer. A primary challenge in experimentally implementing a quantum ...

Borneman, Troy William

2013-01-01T23:59:59.000Z

327

Splitting a C-O bond in dialkylethers with bis(1,2,4-tri-t-butylcyclopentadienyl) cerium-hydride does not occur by a sigma-bond metathesis pathway: a combined experimental and DFT computational study  

SciTech Connect (OSTI)

Addition of diethylether to [1,2,4(Me3C)3C5H2]2CeH, abbreviated Cp'2CeH, gives Cp'2CeOEt and ethane. Similarly, di-n-propyl- or di-n-butylether gives Cp'2Ce(O-n-Pr) and propane or Cp'2Ce(O-n-Bu) and butane, respectively. Using Cp'2CeD, the propane and butane contain deuterium predominantly in their methyl groups. Mechanisms, formulated on the basis of DFT computational studies, show that the reactions begin by an alpha or beta-CH activation with comparable activation barriers but only the beta-CH activation intermediate evolves into the alkoxide product and an olefin. The olefin then inserts into the Ce-H bond forming the alkyl derivative, Cp'2CeR, that eliminates alkane. The alpha-CH activation intermediate is in equilibrium with the starting reagents, Cp'2CeH and the ether, which accounts for the deuterium label in the methyl groups of the alkane. The one-step sigma-bond metathesis mechanism has a much higher activation barrier than either of the two-step mechanisms.

Werkema, Evan; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Andersen, Richard

2010-04-06T23:59:59.000Z

328

A Realist Interpretation of the Quantum Measurement Problem  

E-Print Network [OSTI]

A new, realist interpretation of the quantum measurement processes is given. In this scenario a quantum measurement is a non-equilibrium phase transition in a ``resonant cavity'' formed by the entire physical universe including all its material and energy content. Both the amplitude and the phase of the quantum mechanical wavefunction acquire substantial meaning in this picture, and the probabilistic element is removed from the foundations of quantum mechanics, its apparent presence in the quantum measurement process is viewed as a result of the sensitive dependence on initial/boundary conditions of the non-equilibrium phase transitions in a many degree-of-freedom system. The implications of adopting this realist ontology to the clarification and resolution of lingering issues in the foundations of quantum mechanics, such as wave-particle duality, Heisenberg's uncertainty relation, Schrodinger's Cat paradox, first and higher order coherence of photons and atoms, virtual particles, the existence of commutation relations and quantized behavior, etc., are also presented.

Xiaolei Zhang

2006-02-27T23:59:59.000Z

329

Dark Energy from Quantum Uncertainty of Simultaneity  

E-Print Network [OSTI]

The observed acceleration expansion of the universe was thought attribute to a mysterious dark energy in the framework of the classical general relativity. The dark energy behaves very similar with a vacuum energy in quantum mechanics. However, once the quantum effects are seriously taken into account, it predicts a wrong order of the vacuum energy and leads to a severe fine-tuning, known as the cosmological constant problem. We abandon the standard interpretation that time is a global parameter in quantum mechanics, replace it by a quantum dynamical variable playing the role of an operational quantum clock system. In the framework of reinterpretation of time, we find that the synchronization of two quantum clocks distance apart can not be realized in all rigor at quantum level. Thus leading to an intrinsic quantum uncertainty of simultaneity between spatial interval, which implies a visional vacuum energy fluctuation and gives an observed dark energy density $\\rho_{de}=\\frac{6}{\\pi}L_{P}^{-2}L_{H}^{-2}$, whe...

Luo, M J

2014-01-01T23:59:59.000Z

330

Engineering Nonclassicality in a Mechanical System through Photon Subtraction  

Science Journals Connector (OSTI)

Nonclassical states of a mechanical mode at nonzero temperature are achieved in a scheme that combines radiation-pressure coupling to a light field and photon subtraction. The scheme embodies an original and experimentally realistic way to obtain mesoscopic quantumness by putting together two mature technologies for quantum control. The protocol is quasi-insensitive to mechanical damping.

Mauro Paternostro

2011-05-02T23:59:59.000Z

331

Quantum++ - A C++11 quantum computing library  

E-Print Network [OSTI]

Quantum++ is a general-purpose multi-threaded quantum computing library written in C++11 and composed solely of header files. The library is not restricted to qubit systems or specific quantum information processing tasks, being capable of simulating arbitrary quantum processes. The main design factors taken in consideration were ease of use, portability, and performance.

Vlad Gheorghiu

2014-12-15T23:59:59.000Z

332

Quantum arithmetic with the Quantum Fourier Transform  

E-Print Network [OSTI]

The Quantum Fourier Transform offers an interesting way to perform arithmetic operations on a quantum computer. We review existing Quantum Fourier Transform adders and multipliers and propose some modifications that extend their capabilities. Among the new circuits, we propose a quantum method to compute the weighted average of a series of inputs in the transform domain.

Lidia Ruiz-Perez; Juan Carlos Garcia-Escartin

2014-11-21T23:59:59.000Z

333

Stability of titanium oxide phases in Kohn-Sham density functional A well known problem in practical Kohn-Sham (KS) density functional theory (DFT) calculations is that it yields the wrong order of  

E-Print Network [OSTI]

Stability of titanium oxide phases in Kohn-Sham density functional theory A well known problem in practical Kohn-Sham (KS) density functional theory (DFT) calculations is that it yields the wrong order-DFT, but with different levels of corrections to the exchange-correlation functional. Kohn-Sham density functional theory

Bjørnstad, Ottar Nordal

334

Physics as Quantum Information Processing: Quantum Fields as Quantum Automata  

E-Print Network [OSTI]

Can we reduce Quantum Field Theory (QFT) to a quantum computation? Can physics be simulated by a quantum computer? Do we believe that a quantum field is ultimately made of a numerable set of quantum systems that are unitarily interacting? A positive answer to these questions corresponds to substituting QFT with a theory of quantum cellular automata (QCA), and the present work is examining this hypothesis. These investigations are part of a large research program on a "quantum-digitalization" of physics, with Quantum Theory as a special theory of information, and Physics as emergent from the same quantum-information processing. A QCA-based QFT has tremendous potential advantages compared to QFT, being quantum "ab-initio" and free from the problems plaguing QFT due to the continuum hypothesis. Here I will show how dynamics emerges from the quantum processing, how the QCA can reproduce the Dirac-field phenomenology at large scales, and the kind of departures from QFT that that should be expected at a Planck-scale discreteness. I will introduce the notions of linear field quantum automaton and local-matrix quantum automaton, in terms of which I will provide the solution to the Feynman's problem about the possibility of simulating a Fermi field with a quantum computer.

Giacomo Mauro D'Ariano

2011-10-31T23:59:59.000Z

335

Quantum coherence and correlations in quantum system  

E-Print Network [OSTI]

Criteria of measure quantifying quantum coherence, a unique property of quantum system, are proposed recently. In this paper, we investigate the relative entropic measure of coherence. Based on its analytical expression, we give an operational interpretation of it with respect to the concept of quantum channel. On this basis, we derive the relation about the coherence and the coherent information in any quantum state. From the point of view of quantum measurement, we furthermore give three trade-offs among the coherence, discord-like and deficit-like quantum correlation quantities for any bipartite quantum state. As an application, we discuss the coherent property of the amplitude damping channel.

Zhengjun Xi; Yongming Li; Heng Fan

2014-08-14T23:59:59.000Z

336

Graphene-based qubits in quantum communications  

E-Print Network [OSTI]

We explore the potential application of graphene-based qubits in photonic quantum communications. In particular, the valley pair qubit in double quantum dots of gapped graphene is investigated as a quantum memory in the implementation of quantum repeaters. For the application envisioned here, our work extends the recent study of the qubit (Wu et al., arXiv: 1104.0443; Phys. Rev. B 84, 195463 (2011)) to the case where the qubit is placed in a normal magnetic field-free configuration. It develops, for the configuration, a method of qubit manipulation, based on a unique AC electric field-induced, valley-orbit interaction-derived mechanism in gapped graphene. It also studies the optical response of graphene quantum dots in the configuration, in terms of valley excitation with respect to photonic polarization, and illustrates faithful photon \\leftrightarrow valley quantum state transfers. This work suggests the interesting prospect of an all-graphene approach for the solid state components of a quantum network, e.g., quantum computers and quantum memories in communications.

G. Y. Wu; N. -Y. Lue

2012-04-28T23:59:59.000Z

337

Dimensional Reduction in Quantum Gravity  

E-Print Network [OSTI]

The requirement that physical phenomena associated with gravitational collapse should be duly reconciled with the postulates of quantum mechanics implies that at a Planckian scale our world is not 3+1 dimensional. Rather, the observable degrees of freedom can best be described as if they were Boolean variables defined on a two-dimensional lattice, evolving with time. This observation, deduced from not much more than unitarity, entropy and counting arguments, implies severe restrictions on possible models of quantum gravity. Using cellular automata as an example it is argued that this dimensional reduction implies more constraints than the freedom we have in constructing models. This is the main reason why so-far no completely consistent mathematical models of quantum black holes have been found. Essay dedicated to Abdus Salam.

G. 't Hooft

2009-03-20T23:59:59.000Z

338

DFT+U Study of Polaronic Conduction in Li2O2 and Li2CO3: Implications for LiAir Batteries  

Science Journals Connector (OSTI)

DFT+U Study of Polaronic Conduction in Li2O2 and Li2CO3: Implications for LiAir Batteries ... The emission of greenhouse gases and the local pollution in the cities produced by the fossil fuel-powered vehicles (FFVs) is forcing the development of alternative power systems for automobiles. ... A delocalized solution was found. ...

J. M. Garcia-Lastra; J. S. G. Myrdal; R. Christensen; K. S. Thygesen; T. Vegge

2013-02-15T23:59:59.000Z

339

Quantum enhanced estimation of optical detector efficiencies  

E-Print Network [OSTI]

Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by iden- tifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum channels involving the estimation of phase and loss parameters, we show that estimat- ing the loss parameters associated with a quantum channel and a realistic quantum detector are fundamentally different. While Fock states are provably optimal for the former, we identify a crossover in the nature of the optimal probe state for estimating detector imperfections as a function of the loss parameter. We provide explicit results for on-off and homodyne detectors, the most widely used detectors in quantum photonics technologies.

Barbieri, Marco; Bartley, Tim J; Jin, Xian-Min; Kolthammer, W Steven; Walmsley, Ian A

2015-01-01T23:59:59.000Z

340

Time-optimal navigation through quantum wind  

E-Print Network [OSTI]

The quantum navigation problem of finding the time-optimal control Hamiltonian that transports a given initial state to a target state through quantum wind, that is, under the influence of external fields, is analysed. By lifting the problem from the state space to the space of unitary gates realising the required task, we are able to deduce the form of the solution to the problem by deriving a universal quantum speed limit. The expression thus obtained indicates that further simplifications of this apparently difficult problem are possible if we switch to the interaction picture of quantum mechanics. A complete solution to the navigation problem for an arbitrary quantum system is then obtained, and the behaviour of the solution is illustrated in the case of a two-level system.

Dorje C. Brody; Gary W. Gibbons; David M. Meier

2014-11-17T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Time-optimal navigation through quantum wind  

E-Print Network [OSTI]

The quantum navigation problem of finding the time-optimal control Hamiltonian that transports a given initial state to a target state through quantum wind, that is, under the influence of external fields or potentials, is analysed. By lifting the problem from the state space to the space of unitary gates realising the required task, we are able to deduce the form of the solution to the problem by deriving a universal quantum speed limit. The expression thus obtained indicates that further simplifications of this apparently difficult problem are possible if we switch to the interaction picture of quantum mechanics. A complete solution to the navigation problem for an arbitrary quantum system is then obtained, and the behaviour of the solution is illustrated in the case of a two-level system.

Dorje C. Brody; Gary W. Gibbons; David M. Meier

2015-02-19T23:59:59.000Z

342

Time-Energy Measure for Quantum Processes  

E-Print Network [OSTI]

Quantum mechanics sets limits on how fast quantum processes can run given some system energy through time-energy uncertainty relations, and they imply that time and energy are tradeoff against each other. Thus, we propose to measure the time-energy as a single unit for quantum channels. We consider a time-energy measure for quantum channels and compute lower and upper bounds of it using the channel Kraus operators. For a special class of channels (which includes the depolarizing channel), we can obtain the exact value of the time-energy measure. One consequence of our result is that erasing quantum information requires $\\sqrt{(n+1)/n}$ times more time-energy resource than erasing classical information, where $n$ is the system dimension.

Chi-Hang Fred Fung; H. F. Chau

2013-05-24T23:59:59.000Z

343

Quantum nonlocality  

SciTech Connect (OSTI)

It is argued that the validity of the predictions of quantum theory in certain spin-correlation experiments entails a violation of Einstein's locality idea that no causal influence can act outside the forward light cone. First, two preliminary arguments suggesting such a violation are reviewed. They both depend, in intermediate stages, on the idea that the results of certain unperformed experiments are physically determinate. The second argument is entangled also with the problem of the meaning of physical reality. A new argument having neither of these characteristics is constructed. It is based strictly on the orthodox ideas of Bohr and Heisenberg, and has no realistic elements, or other ingredients, that are alien to orthodox quantum thinking.

Stapp, H.P.

1988-04-01T23:59:59.000Z

344

Quantum Thermometry  

E-Print Network [OSTI]

In this review article we revisit and spell out the details of previous work on how Berry phase can be used to construct a precision quantum thermometer. An important advantage of such a scheme is that there is no need for the thermometer to acquire thermal equilibrium with the sample. This reduces measurement times and avoids precision limitations. We also review how such methods can be used to detect the Unruh effect.

Robert B. Mann; Eduardo Martin-Martinez

2014-05-22T23:59:59.000Z

345

Fractional Quantum Hall States in Graphene  

E-Print Network [OSTI]

We quantum mechanically analyze the fractional quantum Hall effect in graphene. This will be done by building the corresponding states in terms of a potential governing the interactions and discussing other issues. More precisely, we consider a system of particles in the presence of an external magnetic field and take into account of a specific interaction that captures the basic features of the Laughlin series \

Ahmed Jellal; Bellati Malika

2008-05-15T23:59:59.000Z

346

Quantum Energy Regression using Scattering Transforms  

E-Print Network [OSTI]

We present a novel approach to the regression of quantum mechanical energies based on a scattering transform of an intermediate electron density representation. A scattering transform is a deep convolution network computed with a cascade of multiscale wavelet transforms. It possesses appropriate invariant and stability properties for quantum energy regression. This new framework removes fundamental limitations of Coulomb matrix based energy regressions, and numerical experiments give state-of-the-art accuracy over planar molecules.

Hirn, Matthew; Mallat, Stephane

2015-01-01T23:59:59.000Z

347

Terahertz quantum cascade lasers  

Science Journals Connector (OSTI)

...Michael Pepper Terahertz quantum cascade lasers Jerome Faist 1 Lassaad Ajili...developments in terahertz quantum cascade lasers are reviewed. Structures...magnetic confinement| Terahertz quantum cascade lasers. | Recent developments in...

2004-01-01T23:59:59.000Z

348

Quantum Money from Hidden Subspaces  

E-Print Network [OSTI]

Forty years ago, Wiesner pointed out that quantum mechanics raises the striking possibility of money that cannot be counterfeited according to the laws of physics. We propose the first quantum money scheme that is (1) public-key, meaning that anyone can verify a banknote as genuine, not only the bank that printed it, and (2) cryptographically secure, under a "classical" hardness assumption that has nothing to do with quantum money. Our scheme is based on hidden subspaces, encoded as the zero-sets of random multivariate polynomials. A main technical advance is to show that the "black-box" version of our scheme, where the polynomials are replaced by classical oracles, is unconditionally secure. Previously, such a result had only been known relative to a quantum oracle (and even there, the proof was never published). Even in Wiesner's original setting -- quantum money that can only be verified by the bank -- we are able to use our techniques to patch a major security hole in Wiesner's scheme. We give the first p...

Aaronson, Scott

2012-01-01T23:59:59.000Z

349

Quantum Learning Machine  

E-Print Network [OSTI]

We propose a novel notion of a quantum learning machine for automatically controlling quantum coherence and for developing quantum algorithms. A quantum learning machine can be trained to learn a certain task with no a priori knowledge on its algorithm. As an example, it is demonstrated that the quantum learning machine learns Deutsch's task and finds itself a quantum algorithm, that is different from but equivalent to the original one.

Jeongho Bang; James Lim; M. S. Kim; Jinhyoung Lee

2008-03-20T23:59:59.000Z

350

Gravity and the Quantum: Are they Reconcilable?  

E-Print Network [OSTI]

General relativity and quantum mechanics are conflicting theories. The seeds of discord are the fundamental principles on which these theories are grounded. General relativity, on one hand, is based on the equivalence principle, whose strong version establishes the local equivalence between gravitation and inertia. Quantum mechanics, on the other hand, is fundamentally based on the uncertainty principle, which is essentially nonlocal in the sense that a particle does not follow one trajectory, but infinitely many trajectories, each one with a different probability. This difference precludes the existence of a quantum version of the strong equivalence principle, and consequently of a quantum version of general relativity. Furthermore, there are compelling experimental evidences that a quantum object in the presence of a gravitational field violates the weak equivalence principle. Now it so happens that, in addition to general relativity, gravitation has an alternative, though equivalent description, given by teleparallel gravity, a gauge theory for the translation group. In this theory torsion, instead of curvature, is assumed to represent the gravitational field. These two descriptions lead to the same classical results, but are conceptually different. In general relativity, curvature geometrizes the interaction, while torsion in teleparallel gravity acts as a force, similar to the Lorentz force of electrodynamics. Because of this peculiar property, teleparallel gravity describes the gravitational interaction without requiring any of the equivalence principles. The replacement of general relativity by teleparallel gravity may, in consequence, lead to a conceptual reconciliation of gravitation with quantum mechanics.

R. Aldrovandi; J. G. Pereira; K. H. Vu

2005-09-14T23:59:59.000Z

351

Elementary quantum cloning machines  

E-Print Network [OSTI]

The task of reception of a copy of an arbitrary quantum state with use of a minimum quantity of quantum operations is considered.

V. N. Dumachev

2006-02-03T23:59:59.000Z

352

Quantum Coherence of Relic Neutrinos  

Science Journals Connector (OSTI)

We argue that in at least a portion of the history of the Universe the relic background neutrinos are spatially extended, coherent superpositions of mass states. We show that an appropriate quantum mechanical treatment affects the neutrino mass values derived from cosmological data. The coherence scale of these neutrino flavor wave packets can be an appreciable fraction of the causal horizon size, raising the possibility of spacetime curvature-induced decoherence.

George M. Fuller and Chad T. Kishimoto

2009-05-22T23:59:59.000Z

353

Reversible information-to-energy conversions in a quantum hybrid system  

Science Journals Connector (OSTI)

We investigate the properties of a quantum hybrid opto-mechanical transducer in the context of information thermodynamics, and show that it provides a valuable platform to monitor...

Auffeves, Alexia; Elouard, Cyril; Richard, Maxime

354

Simulating quantum systems on a quantum computer  

Science Journals Connector (OSTI)

...A-eigenstates in the original system state. Also after each observation...1998) Simulating quantum systems on a quantum computer 321 system will be in an eigenstate of...the energy eigenstates. An analysis shows that the relative accuracy...

1998-01-01T23:59:59.000Z

355

Development of multicomponent hybrid density functional theory with polarizable continuum model for the analysis of nuclear quantum effect and solvent effect on NMR chemical shift  

SciTech Connect (OSTI)

We have developed the multicomponent hybrid density functional theory [MC-(HF+DFT)] method with polarizable continuum model (PCM) for the analysis of molecular properties including both nuclear quantum effect and solvent effect. The chemical shifts and H/D isotope shifts of the picolinic acid N-oxide (PANO) molecule in chloroform and acetonitrile solvents are applied by B3LYP electron exchange-correlation functional for our MC-(HF+DFT) method with PCM (MC-B3LYP/PCM). Our MC-B3LYP/PCM results for PANO are in reasonable agreement with the corresponding experimental chemical shifts and isotope shifts. We further investigated the applicability of our method for acetylacetone in several solvents.

Kanematsu, Yusuke; Tachikawa, Masanori [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)] [Quantum Chemistry Division, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)

2014-04-28T23:59:59.000Z

356

Thermalization of isolated quantum systems  

E-Print Network [OSTI]

Understanding the evolution towards thermal equilibrium of an isolated quantum system is at the foundation of statistical mechanics and a subject of interest in such diverse areas as cold atom physics or the quantum mechanics of black holes. Since a pure state can never evolve into a thermal density matrix, the Eigenstate Thermalization Hypothesis (ETH) has been put forward by Deutsch and Srednicki as a way to explain this apparent thermalization, similarly to what the ergodic theorem does in classical mechanics. In this paper this hypothesis is tested numerically. First, it is observed that thermalization happens in a subspace of states (the Krylov subspace) with dimension much smaller than that of the total Hilbert space. We check numerically the validity of ETH in such a subspace, for a system of hard core bosons on a two-dimensional lattice. We then discuss how well the eigenstates of the Hamiltonian projected on the Krylov subspace represent the true eigenstates. This discussion is aided by bringing the projected Hamiltonian to the tridiagonal form and interpreting it as an Anderson localization problem for a finite one-dimensional chain. We also consider thermalization of a subsystem and argue that generation of a large entanglement entropy can lead to a thermal density matrix for the subsystem well before the whole system thermalizes. Finally, we comment on possible implications of ETH in quantum gravity.

Sergei Khlebnikov; Martin Kruczenski

2014-03-12T23:59:59.000Z

357

A discussion on the origin of quantum probabilities  

SciTech Connect (OSTI)

We study the origin of quantum probabilities as arising from non-Boolean propositional-operational structures. We apply the method developed by Cox to non distributive lattices and develop an alternative formulation of non-Kolmogorovian probability measures for quantum mechanics. By generalizing the method presented in previous works, we outline a general framework for the deduction of probabilities in general propositional structures represented by lattices (including the non-distributive case). -- Highlights: Several recent works use a derivation similar to that of R.T. Cox to obtain quantum probabilities. We apply Coxs method to the lattice of subspaces of the Hilbert space. We obtain a derivation of quantum probabilities which includes mixed states. The method presented in this work is susceptible to generalization. It includes quantum mechanics and classical mechanics as particular cases.

Holik, Federico, E-mail: olentiev2@gmail.com [Universidad Nacional de La Plata, Instituto de Fsica (IFLP-CCT-CONICET), C.C. 727, 1900 La Plata (Argentina) [Universidad Nacional de La Plata, Instituto de Fsica (IFLP-CCT-CONICET), C.C. 727, 1900 La Plata (Argentina); Departamento de Matemtica - Ciclo Bsico Comn, Universidad de Buenos Aires - Pabelln III, Ciudad Universitaria, Buenos Aires (Argentina); Senz, Manuel [Departamento de Matemtica - Ciclo Bsico Comn, Universidad de Buenos Aires - Pabelln III, Ciudad Universitaria, Buenos Aires (Argentina)] [Departamento de Matemtica - Ciclo Bsico Comn, Universidad de Buenos Aires - Pabelln III, Ciudad Universitaria, Buenos Aires (Argentina); Plastino, Angel [Universitat de les Illes Balears and IFISC-CSIC, 07122 Palma de Mallorca (Spain)] [Universitat de les Illes Balears and IFISC-CSIC, 07122 Palma de Mallorca (Spain)

2014-01-15T23:59:59.000Z

358

Molecular Quantum Similarity and the Fundamentals of QSAR  

Science Journals Connector (OSTI)

Molecular Quantum Similarity and the Fundamentals of QSAR ... His research covers the following topics:? molecular electronic density fitting; QSAR; and scientific programming, both serial and parallel processing. ... Among all developments, the most important one has been the description of a fundamental quantum QSPR (QQSPR or Q2SPR) equation's existence, which also demonstrates that the empirical QSPR models can be generally founded into a well-defined relationship16 of quantum mechanical origin. ...

Emili Besal; Xavier Girons; Llus Amat; Ramon Carb-Dorca

2002-04-04T23:59:59.000Z

359

A Novel, Green Technology for the Production of Aromatic Thiol from Aromatic Sulfonyl Chloride  

E-Print Network [OSTI]

Functional Theory (DFT), a quantum mechanical method, was used to investigate the new aromatic thiol production technology at the molecular level in aspects including reaction species adsorption and transition state determination. Plant design methods...

Atkinson, Bradley R.

2010-01-16T23:59:59.000Z

360

Values and the quantum conception of man  

SciTech Connect (OSTI)

Classical mechanics is based upon a mechanical picture of nature that is fundamentally incorrect. It has been replaced at the basic level by a radically different theory: quantum mechanics. This change entails an enormous shift in one`s basic conception of nature, one that can profoundly alter the scientific image of man himself. Self-image is the foundation of values, and the replacement of the mechanistic self-image derived from classical mechanics by one concordant with quantum mechanics may provide the foundation of a moral order better suited to today`s times, a self-image that endows human life with meaning, responsibility, and a deeper linkage to nature as a whole.

Stapp, H.P.

1995-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Selection of fluxing agent for coal ash and investigation of fusion mechanism: a first-principles study  

SciTech Connect (OSTI)

An approach based on the ab initio quantum chemical modeling (CASTEP, generalized gradient approximation (GGA), and density functional theory (DFT)) was first employed to guide the selection of the appropriate fluxing agent to reduce the coal ash melting temperature. Two kinds of typical Chinese coal ash A and B with a high-melting temperature were chosen as the investigated subjects. Result of the calculation shows that mullite mineral, which is the main component of coal ash, is easier to combine with an electron acceptor than with an electron donor. Because the cations of borax (Na{sub 2}B{sub 4}O{sub 7}10H{sub 2}O) and limestone can act as electron acceptors, borax and limestone were selected as the fluxing agents in our experiment. Results of the experiment show that the melting temperatures of coal ash A and B are both decreased by borax and limestone, respectively. Moreover, borax has a better fluxing effect than limestone under the same conditions. The further numerical study on the coal ash fusing mechanism indicates that the Na{sup +} and Ca{sup 2+} cations, as acceptors, can enter into the crystal lattice of mullite mainly through O(7) and O(8) and then cause the Al(6)-O(8) and Al(5)-O(7) bonds to rupture in the (AlO{sub 6})-octahedron. From this, mullite is forced to transform to feldspar and corundum minerals that have a low binding energy. Because of the phase change of minerals in the coal ash, the coal ash melting temperature is decreased by adding borax and limestone. 27 refs., 8 figs., 3 tabs.

Jie Li; Mei-Fang Du; Zhong-Xiao Zhang; Rong-Qing Guan; Yu-Shuang Chen; Ting-Yu Liu [University of Shanghai for Science and Technology, Shanghai (China). College of Science, and Department of Power Engineering

2009-01-15T23:59:59.000Z

362

Intermediate-band photosensitive device with quantum dots having tunneling barrier embedded in organic matrix  

DOE Patents [OSTI]

A plurality of quantum dots each have a shell. The quantum dots are embedded in an organic matrix. At least the quantum dots and the organic matrix are photoconductive semiconductors. The shell of each quantum dot is arranged as a tunneling barrier to require a charge carrier (an electron or a hole) at a base of the tunneling barrier in the organic matrix to perform quantum mechanical tunneling to reach the respective quantum dot. A first quantum state in each quantum dot is between a lowest unoccupied molecular orbital (LUMO) and a highest occupied molecular orbital (HOMO) of the organic matrix. Wave functions of the first quantum state of the plurality of quantum dots may overlap to form an intermediate band.

Forrest, Stephen R. (Ann Arbor, MI)

2008-08-19T23:59:59.000Z

363

Quantum optomechanical piston engines powered by heat  

E-Print Network [OSTI]

We study two different models of optomechanical systems where a temperature gradient between two radiation baths is exploited for inducing self-sustained coherent oscillations of a mechanical resonator. Viewed from a thermodynamic perspective, such systems represent quantum instances of self-contained thermal machines converting heat into a periodic mechanical motion and thus they can be interpreted as nano-scale analogues of macroscopic piston engines. Our models are potentially suitable for testing fundamental aspects of quantum thermodynamics in the laboratory and for applications in energy efficient nanotechnology.

Andrea Mari; Alessandro Farace; Vittorio Giovannetti

2014-07-31T23:59:59.000Z

364

Quantum Cybernetics and Complex Quantum Systems Science - A Quantum Connectionist Exploration  

E-Print Network [OSTI]

Quantum cybernetics and its connections to complex quantum systems science is addressed from the perspective of complex quantum computing systems. In this way, the notion of an autonomous quantum computing system is introduced in regards to quantum artificial intelligence, and applied to quantum artificial neural networks, considered as autonomous quantum computing systems, which leads to a quantum connectionist framework within quantum cybernetics for complex quantum computing systems. Several examples of quantum feedforward neural networks are addressed in regards to Boolean functions' computation, multilayer quantum computation dynamics, entanglement and quantum complementarity. The examples provide a framework for a reflection on the role of quantum artificial neural networks as a general framework for addressing complex quantum systems that perform network-based quantum computation, possible consequences are drawn regarding quantum technologies, as well as fundamental research in complex quantum systems science and quantum biology.

Carlos Pedro Gonalves

2014-02-05T23:59:59.000Z

365

A Full Characterization of Quantum Advice Scott Aaronson #  

E-Print Network [OSTI]

in quantum mechanics are continuous. A natural compromise is to try to specify # approximately, i.e., to giveA Full Characterization of Quantum Advice Scott Aaronson # MIT Andrew Drucker + MIT Abstract We Hamiltonian H on poly (n) qubits (e.g., a sum of two­qubit interactions), such that any ground state of H can

Aaronson, Scott

366

A Full Characterization of Quantum Advice Scott Aaronson  

E-Print Network [OSTI]

in quantum mechanics are continuous. A natural compromise is to try to specify approximately, i.e., to giveA Full Characterization of Quantum Advice Scott Aaronson MIT Andrew Drucker MIT Abstract We prove on poly (n) qubits (e.g., a sum of two-qubit interactions), such that any ground state of H can be used

Aaronson, Scott

367

The Quantum Absorption Refrigerator Amikam Levy and Ronnie Kosloff  

E-Print Network [OSTI]

, 07.20.Pe,05.30.-d I. INTRODUCTION The adsorption chiller is a refrigerator which employs a heat source to replace mechanical work for driving a heat pump [1]. The first device was developed in 1850 c J h P Tc Th Tw - - - 0 FIG. 1: The quantum trickle: A quantum heat pump des- ignated

Kosloff, Ronnie

368

Quantum microscopic approach to low-energy heavy ion collisions  

E-Print Network [OSTI]

of nuclear reactions at low energy where quantum effects play a significant role is an important challenge of nuclear physics. The interplay between nuclear structure and reaction mechanisms is crucial at energiesQuantum microscopic approach to low-energy heavy ion collisions C´edric Simenel1,2, Aditya Wakhle2

369

Quantum implicit computational complexity  

Science Journals Connector (OSTI)

We introduce a quantum lambda calculus inspired by Lafont's Soft Linear Logic and capturing the polynomial quantum complexity classes EQP, BQP and ZQP. The calculus is based on the ''classical control and quantum data'' paradigm. This is the first example ... Keywords: Implicit computational complexity, Lambda calculus, Quantum computation

Ugo Dal Lago; Andrea Masini; Margherita Zorzi

2010-01-01T23:59:59.000Z

370

Hybrid quantum devices and quantum engineering  

E-Print Network [OSTI]

We discuss prospects of building hybrid quantum devices involving elements of atomic and molecular physics, quantum optics and solid state elements with the attempt to combine advantages of the respective systems in compatible experimental setups. In particular, we summarize our recent work on quantum hybrid devices and briefly discuss recent ideas for quantum networks. These include interfacing of molecular quantum memory with circuit QED, and using nanomechanical elements strongly coupled to qubits represented by electronic spins, as well as single atoms or atomic ensembles.

Margareta Wallquist; Klemens Hammerer; Peter Rabl; Mikhail Lukin; Peter Zoller

2009-11-19T23:59:59.000Z

371

LANL | Physics | Quantum Information  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Breakthrough quantum information Breakthrough quantum information science and technology Physics Division's quantum information science and technology capability supports present and future Laboratory missions in cyber-security, sensing, nonproliferation, information science, and materials. Collaborating with researchers throughout Los Alamos and leading institutions in the nation, Physics Division scientists are involved in projects in quantum communications, including quantum key distribution and quantum-enabled security and networking, and in quantum cold-atom physics. Recent fundamental science results include the ability to "paint" potentials that can trap Bose-Einstein condensates into geometric forms, such as the toroidal ring of clusters, the density of which is measured in

372

Ising Quantum Chain and Biological Evolution Holger Wagner 1 and Ellen Baake 2  

E-Print Network [OSTI]

Ising Quantum Chain and Biological Evolution Holger Wagner 1 and Ellen Baake 2 1 Institut f to be equivalent to an Ising quantum chain. Three explicit examples with representative fitness landscapes are dis of an Ising quantum chain. Methods of statistical mechanics, which exploit the translation or permutation

Baake, Ellen

373

Dimensional reduction and quantum-to-classical reduction at high temperatures  

Science Journals Connector (OSTI)

We discuss the relation between dimensional reduction in quantum field theories at finite temperature and a familiar quantum-mechanical phenomenon that quantum effects become negligible at high temperatures. Fermi and Bose fields are compared in this respect. We show that decoupling of fermions from the dimensionally reduced theory can be related to the nonexistence of classical statistics for a Fermi field.

M. A. Stephanov

1995-09-15T23:59:59.000Z

374

Hybrid Quantum Cloning Machine  

E-Print Network [OSTI]

In this work, we introduce a special kind of quantum cloning machine called Hybrid quantum cloning machine. The introduced Hybrid quantum cloning machine or transformation is nothing but a combination of pre-existing quantum cloning transformations. In this sense it creates its own identity in the field of quantum cloners. Hybrid quantum cloning machine can be of two types: (i) State dependent and (ii) State independent or Universal. We study here the above two types of Hybrid quantum cloning machines. Later we will show that the state dependent hybrid quantum-cloning machine can be applied on only four input states. We will also find in this paper another asymmetric universal quantum cloning machine constructed from the combination of optimal universal B-H quantum cloning machine and universal anti-cloning machine. The fidelities of the two outputs are different and their values lie in the neighborhood of ${5/6} $

Satyabrata Adhikari; A. K. Pati; Indranil Chakrabarty; B. S. Choudhury

2007-05-04T23:59:59.000Z

375

Quantum optical waveform conversion  

E-Print Network [OSTI]

Currently proposed architectures for long-distance quantum communication rely on networks of quantum processors connected by optical communications channels [1,2]. The key resource for such networks is the entanglement of matter-based quantum systems with quantum optical fields for information transmission. The optical interaction bandwidth of these material systems is a tiny fraction of that available for optical communication, and the temporal shape of the quantum optical output pulse is often poorly suited for long-distance transmission. Here we demonstrate that nonlinear mixing of a quantum light pulse with a spectrally tailored classical field can compress the quantum pulse by more than a factor of 100 and flexibly reshape its temporal waveform, while preserving all quantum properties, including entanglement. Waveform conversion can be used with heralded arrays of quantum light emitters to enable quantum communication at the full data rate of optical telecommunications.

D Kielpinski; JF Corney; HM Wiseman

2010-10-11T23:59:59.000Z

376

Quantum Bootstrapping via Compressed Quantum Hamiltonian Learning  

E-Print Network [OSTI]

Recent work has shown that quantum simulation is a valuable tool for learning empirical models for quantum systems. We build upon these results by showing that a small quantum simulators can be used to characterize and learn control models for larger devices for wide classes of physically realistic Hamiltonians. This leads to a new application for small quantum computers: characterizing and controlling larger quantum computers. Our protocol achieves this by using Bayesian inference in concert with Lieb-Robinson bounds and interactive quantum learning methods to achieve compressed simulations for characterization. Whereas Fisher information analysis shows that current methods which employ short-time evolution are suboptimal, interactive quantum learning allows us to overcome this limitation. We illustrate the efficiency of our bootstrapping protocol by showing numerically that an 8-qubit Ising model simulator can be used to calibrate and control a 50 qubit Ising simulator while using only about 750 kilobits of experimental data.

Nathan Wiebe; Christopher Granade; David G. Cory

2014-09-04T23:59:59.000Z

377

Integrable Quantum Computation  

E-Print Network [OSTI]

Integrable quantum computation is defined as quantum computing via the integrable condition, in which two-qubit gates are either nontrivial unitary solutions of the Yang--Baxter equation or the Swap gate (permutation). To make the definition clear, in this article, we explore the physics underlying the quantum circuit model, and then present a unified description on both quantum computing via the Bethe ansatz and quantum computing via the Yang--Baxter equation.

Yong Zhang

2011-11-16T23:59:59.000Z

378

Extremal quantum protocols  

E-Print Network [OSTI]

Generalized quantum instruments correspond to measurements where the input and output are either states or more generally quantum circuits. These measurements describe any quantum protocol including games, communications, and algorithms. The set of generalized quantum instruments with a given input and output structure is a convex set. Here we investigate the extremal points of this set for the case of finite dimensional quantum systems and generalized instruments with finitely many outcomes. We derive algebraic necessary and sufficient conditions for extremality.

Giacomo Mauro D'Ariano; Paolo Perinotti; Michal Sedlak

2011-01-25T23:59:59.000Z

379

Thermodynamic Limits, Non-commutative Probability, and Quantum Entanglement  

E-Print Network [OSTI]

We construct a rigourous model of quantum measurement. A two-state model of a negative temperature amplifier, such as a laser, is taken to a classical thermodynamic limit. In the limit, it becomes a classical measurement apparatus obeying the stochastic axioms of quantum mechanics. Thus we derive the probabilities from a deterministic Schroedinger's equation by procedures analogous to those of classical statistical mechanics. This requires making precise the notion of `macroscopic.'

Joseph F. Johnson

2005-07-02T23:59:59.000Z

380

Validity of the Second Law in Nonextensive Quantum Thermodynamics  

Science Journals Connector (OSTI)

The second law of thermodynamics in nonextensive statistical mechanics is discussed in the quantum regime. Making use of the convexity property of the generalized relative entropy associated with the Tsallis entropy indexed by q, Clausius inequality is shown to hold in the range q?(0,???2]. This restriction on the range of the entropic index, q, is purely quantum mechanical and there exists no upper bound of q for validity of the second law in classical theory.

Sumiyoshi Abe and A. K. Rajagopal

2003-09-17T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Structural and Energetic Analysis of MgxM1?x(OH)2 (M = Zn, Cu or Ca) Brucite-Like Compounds by DFT Calculations  

Science Journals Connector (OSTI)

Structural and Energetic Analysis of MgxM1?x(OH)2 (M = Zn, Cu or Ca) Brucite-Like Compounds by DFT Calculations ... Brucite-like mixed hydroxides of the general formula MgxM1?x(OH)2 for M = Zn, Cu or Ca were studied by density functional theory within pseudopotential approximation, plane waves basis set, and periodic boundary conditions. ... Brucite, which is the mineral form of magnesium hydroxide, is a commonly occurring material. ...

Deyse G. Costa; Alexandre B. Rocha; Wladmir F. Souza; Sandra Shirley X. Chiaro; Alexandre A. Leito

2008-06-28T23:59:59.000Z

382

Quantum reference frames and deformed symmetries  

SciTech Connect (OSTI)

In the context of constrained quantum mechanics, reference systems are used to construct relational observables that are invariant under the action of the symmetry group. Upon measurement of a relational observable, the reference system undergoes an unavoidable measurement 'back-action' that modifies its properties. In a quantum-gravitational setting, it has been argued that such a back-action may produce effects that are described at an effective level as a form of deformed (or doubly) special relativity. We examine this possibility using a simple constrained system that has been extensively studied in the context of quantum information. While our conclusions support the idea of a symmetry deformation, they also reveal a host of other effects that may be relevant to the context of quantum gravity, and could potentially conceal the symmetry deformation.

Girelli, Florian [SISSA, Via Beirut 2-4, 34014 Trieste (Italy) and INFN, Sezione di Trieste, Trieste (Italy); Poulin, David [Center for the Physics of Information, California Institute of Technology, Pasadena, CA 91125 (United States)

2008-05-15T23:59:59.000Z

383

Quantum reference frames and deformed symmetries  

Science Journals Connector (OSTI)

In the context of constrained quantum mechanics, reference systems are used to construct relational observables that are invariant under the action of the symmetry group. Upon measurement of a relational observable, the reference system undergoes an unavoidable measurement back-action that modifies its properties. In a quantum-gravitational setting, it has been argued that such a back-action may produce effects that are described at an effective level as a form of deformed (or doubly) special relativity. We examine this possibility using a simple constrained system that has been extensively studied in the context of quantum information. While our conclusions support the idea of a symmetry deformation, they also reveal a host of other effects that may be relevant to the context of quantum gravity, and could potentially conceal the symmetry deformation.

Florian Girelli and David Poulin

2008-05-12T23:59:59.000Z

384

The Frobenius formalism in Galois quantum systems  

E-Print Network [OSTI]

Quantum systems in which the position and momentum take values in the ring ${\\cal Z}_d$ and which are described with $d$-dimensional Hilbert space, are considered. When $d$ is the power of a prime, the position and momentum take values in the Galois field $GF(p^ \\ell)$, the position-momentum phase space is a finite geometry and the corresponding `Galois quantum systems' have stronger properties. The study of these systems uses ideas from the subject of field extension in the context of quantum mechanics. The Frobenius automorphism in Galois fields leads to Frobenius subspaces and Frobenius transformations in Galois quantum systems. Links between the Frobenius formalism and Riemann surfaces, are discussed.

A. Vourdas

2006-05-05T23:59:59.000Z

385

Carbon?Oxygen Bond Forming Mechanisms in Rhenium Oxo-Alkyl Complexes  

SciTech Connect (OSTI)

Three C?X bond formation mechanisms observed in the oxidation of (HBpz{sub 3})ReO(R)(OTf) [HBpz{sub 3} = hydrotris(1-pyrazolyl)borate; R = Me, Et, and iPr; OTf = OSO{sub 2}CF{sub 3}] by dimethyl sulfoxide (DMSO) were investigated using quantum mechanics (M06//B3LYP DFT) combined with solvation (using the PBF Poisson?Boltzmann polarizable continuum solvent model). For R = Et we find the alkyl group is activated through ?-hydrogen abstraction by external base OTf{sup ?} with a free energy barrier of only 12.0 kcal/mol, leading to formation of acetaldehyde. Alternatively, ethyl migration across the M?O bond (leading to the formation of acetaldehyde and ethanol) poses a free energy barrier of 22.1 kcal/mol, and the previously proposed ?-hydrogen transfer to oxo (a 2+2 forbidden reaction) poses a barrier of 44.9 kcal/mol. The rate-determining step to formation of the final product acetaldehyde is an oxygen atom transfer from DMSO to the ethylidene, with a free energy barrier of 15.3 kcal/mol. When R = iPr, the alkyl 1,2-migration pathway becomes the more favorable pathway (both kinetically and thermodynamically), with a free energy barrier (?G{sup ?} = 11.8 kcal/mol) lower than ?-hydrogen abstraction by OTf{sup ?} (?G{sup ?} = 13.5 kcal/mol). This suggests the feasibility of utilizing this type of migration to functionalize M?R to M?OR. We also considered the nucleophilic attack of water and ammonia on the Re-ethylidene ?-carbon as a means of recovering two-electron-oxidized products from an alkane oxidation. Nucleophilic attack (with internal deprotonation of the nucleophile) is exothermic. However, the subsequent protonolysis of the Re?alkyl bond (to liberate an alcohol or amine) poses a barrier of 37.0 or 42.4 kcal/mol, respectively. Where comparisons are possible, calculated free energies agree very well with experimental measurements.

Cheng, Mu-Jeng; Nielsen, Robert J; Ahlquist, Marten; Goddard, William A

2010-01-01T23:59:59.000Z

386

DFT studies of Indium Nanoclusters (Inn where n=3-10) and Nanotube and their interaction with molecular hydrogen  

E-Print Network [OSTI]

Density functional theory calculations have been performed on Indium nanoclusters (Inn, n= 3 to 10) to explore the relative stability among their different isomers and interaction with H2. Geometry optimizations starting from initial candidate geometries were performed for each cluster size, so as to determine a few low energy isomers for each size. Clusters with planar configuration and high symmetry are found to be more stable. For n=8 there comes transition from 2D to 3D structures, which formed by stacking of planar rings are most stable. Energetically favorable isomers of indium nanoclusters for each size were considered to get H2 adsorbed. In general H2 interaction with these clusters is week but with odd index i.e. 5, 7 and 9 is significant. Indium nanotube also indicates H2 adsorption but Eads increases many folds on introduction of defect in the tube. On basis of these DFT studies we propose indium nanotubes and clusters of particular size appear to be good candidate for hydrogen storage materials.

Baig, Mirza Wasif; Ahmad, Idrees; Siddiq, Muhammad

2014-01-01T23:59:59.000Z

387

Construction of relativistic quantum theory: a progress report  

SciTech Connect (OSTI)

We construct the particulate states of quantum physics using a recursive computer program that incorporates non-determinism by means of locally arbitrary choices. Quantum numbers and coupling constants arise from the construction via the unique 4-level combinatorial hierarchy. The construction defines indivisible quantum events with the requisite supraluminal correlations, yet does not allow supraluminal communication. Measurement criteria incorporate c, h-bar and m/sub p/ or (not ''and'') G, connected to laboratory events via finite particle number scattering theory and the counter paradigm. The resulting theory is discrete throughout, contains no infinities, and, as far as we have developed it, is in agreement with quantum mechanical and cosmological fact.

Noyes, H.P.

1986-06-01T23:59:59.000Z

388

Quantum Matter-Photonics Framework: Analyses of Chemical Conversion Processes  

E-Print Network [OSTI]

A quantum Matter-Photonics framework is adapted to help scrutinize chemical reaction mechanisms and used to explore a process mapped from chemical tree topological model. The chemical concept of bond knitting/breaking is reformulated via partitioned base sets leading to an abstract and general quantum presentation. Pivotal roles are assigned to entanglement, coherence,de-coherence and Feshbach resonance quantum states that permit apprehend gating states in conversion processes. A view from above in the state energy eigenvalue ladder, belonging to full system spectra complement the standard view from ground state. A full quantum physical view supporting chemical change obtains.

O. Tapia

2014-10-29T23:59:59.000Z

389

Methanol Synthesis from CO2 Hydrogenation over a Pd4/In2O3 Model Catalyst: A Combined DFT and Kinetic Study  

SciTech Connect (OSTI)

Methanol synthesis from CO2 hydrogenation on Pd4/In2O3 has been investigated using density functional theory (DFT) and microkinetic modeling. In this study, three possible routes in the reaction network of CO2 + H2 ? CH3OH + H2O have been examined. Our DFT results show that the HCOO route competes with the RWGS route whereas a high activation barrier kinetically blocks the HCOOH route. DFT results also suggest that H2COO* + H* ? H2CO* +OH* and cis-COOH* + H* ?CO* + H2O* are the rate limiting steps in the HCOO route and the RWGS route, respectively. Microkinetic modeling results demonstrate that the HCOO route is the dominant reaction route for methanol synthesis from CO2 hydrogenation. We found that the activation of H adatom on the small Pd cluster and the presence of H2O on the In2O3 substrate play important roles in promoting the methanol synthesis. The hydroxyl adsorbed at the interface of Pd4/In2O3 induces the transformation of the supported Pd4 cluster from a butterfly structure into a tetrahedron structure. This important structure change not only indicates the dynamical nature of the supported nanoparticle catalyst structure during the reaction but also shifts the final hydrogenation step from H2COH to CH3O.

Ye, Jingyun; Liu, Changjun; Mei, Donghai; Ge, Qingfeng

2014-08-01T23:59:59.000Z

390

Ultralong quantum optical storage using reversible inhomogeneous spin ensembles with an optical locking method  

E-Print Network [OSTI]

A novel method of multi-bit quantum optical data storage is presented, where the storage time can be lengthened far beyond the spin phase-decay time in a reversible spin inhomogeneous system excited by consecutive resonant Raman optical data pulses. The ultralong storage time is obtained by an optical population locking mechanism of modified rephasing process. This gives potentials to quantum repeaters utilizing quantum memories for long distance quantum communications, in which ultralong storage time plays a major role.

Byoung S. Ham

2008-04-23T23:59:59.000Z

391

Gaussian quantum information  

Science Journals Connector (OSTI)

The science of quantum information has arisen over the last two decades centered on the manipulation of individual quanta of information, known as quantum bits or qubits. Quantum computers, quantum cryptography, and quantum teleportation are among the most celebrated ideas that have emerged from this new field. It was realized later on that using continuous-variable quantum information carriers, instead of qubits, constitutes an extremely powerful alternative approach to quantum information processing. This review focuses on continuous-variable quantum information processes that rely on any combination of Gaussian states, Gaussian operations, and Gaussian measurements. Interestingly, such a restriction to the Gaussian realm comes with various benefits, since on the theoretical side, simple analytical tools are available and, on the experimental side, optical components effecting Gaussian processes are readily available in the laboratory. Yet, Gaussian quantum information processing opens the way to a wide variety of tasks and applications, including quantum communication, quantum cryptography, quantum computation, quantum teleportation, and quantum state and channel discrimination. This review reports on the state of the art in this field, ranging from the basic theoretical tools and landmark experimental realizations to the most recent successful developments.

Christian Weedbrook; Stefano Pirandola; Ral Garca-Patrn; Nicolas J. Cerf; Timothy C. Ralph; Jeffrey H. Shapiro; Seth Lloyd

2012-05-01T23:59:59.000Z

392

Quantum fields on closed timelike curves  

SciTech Connect (OSTI)

Recently, there has been much interest in the evolution of quantum particles on closed timelike curves (CTCs). However, such models typically assume pointlike particles with only two degrees of freedom; a very questionable assumption given the relativistic setting of the problem. We show that it is possible to generalize the Deutsch model of CTCs to fields using the equivalent circuit formalism. We give examples for coherent, squeezed, and single-photon states interacting with the CTC via a beamsplitter. The model is then generalized further to account for the smooth transition to normal quantum mechanics as the CTC becomes much smaller than the size of the modes interacting on it. In this limit, we find that the system behaves like a standard quantum-mechanical feedback loop.

Pienaar, J. L.; Myers, C. R.; Ralph, T. C. [School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Queensland (Australia)

2011-12-15T23:59:59.000Z

393

Observation of non-Markovian micro-mechanical Brownian motion  

E-Print Network [OSTI]

At the heart of understanding the emergence of a classical world from quantum theory is the insight that all macroscopic quantum systems are to some extent coupled to an environment and hence are open systems. The associated loss of quantum coherence, i.e., decoherence, is also detrimental for quantum information processing applications. In contrast, properly engineered quantum noise can counteract decoherence and can even be used in robust quantum state generation. To exploit the detailed dynamics of a quantum system it is therefore crucial to obtain both good knowledge and control over its environment. Here we present a method to reconstruct the relevant properties of the environment, that is, its spectral density, of the center of mass motion of a micro-mechanical oscillator. We observe a clear signature of non-Markovian Brownian motion, which is in contrast to the current paradigm to treat the thermal environment of mechanical quantum resonators as fully Markovian. The presented method, inspired by methods of system identification, can easily be transferred to other harmonic systems that are embedded in a complex environment, for example electronic or nuclear spin states in a solid state matrix. Our results also open up a route for mechanical quantum state engineering via coupling to unorthodox reservoirs.

S. Groeblacher; A. Trubarov; N. Prigge; M. Aspelmeyer; J. Eisert

2014-07-16T23:59:59.000Z

394

Quantum Information Causality  

Science Journals Connector (OSTI)

How much information can a transmitted physical system fundamentally communicate? We introduce the principle of quantum information causality, which states the maximum amount of quantum information that a quantum system can communicate as a function of its dimension, independently of any previously shared quantum physical resources. We present a new quantum information task, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs.

Damin Pitala-Garca

2013-05-22T23:59:59.000Z

395

Fiber Hamiltonians in the nonrelativistic quantum electrodynamics  

E-Print Network [OSTI]

of Mathematics, Kyushu University, Hakozaki, Higashi­ku, 6­10­1, Fukuoka 812­8581, Japan. July 7, 2006 Abstract an interaction between a quantum mechanical particle (electron) and a quantized radiation field. The Hamiltonian H of this system is defined as a self­adjoint operator minimally coupled to the quantized radiation

396

The Quantum Hall Effect in Graphene  

E-Print Network [OSTI]

We investigate the quantum Hall effect in graphene. We argue that in graphene in presence of an external magnetic field there is dynamical generation of mass by a rearrangement of the Dirac sea. We show that the mechanism breaks the lattice valley degeneracy only for the $n=0$ Landau levels and leads to the new observed $\

Paolo Cea

2011-01-29T23:59:59.000Z

397

CORRELATIONS IN CONFINED QUANTUM PLASMAS  

SciTech Connect (OSTI)

This is the final report for the project 'Correlations in Confined Quantum Plasmas', NSF-DOE Partnership Grant DE FG02 07ER54946, 8/1/2007 - 7/30/2010. The research was performed in collaboration with a group at Christian Albrechts University (CAU), Kiel, Germany. That collaboration, almost 15 years old, was formalized during the past four years under this NSF-DOE Partnership Grant to support graduate students at the two institutions and to facilitate frequent exchange visits. The research was focused on exploring the frontiers of charged particle physics evolving from new experimental access to unusual states associated with confinement. Particular attention was paid to combined effects of quantum mechanics and confinement. A suite of analytical and numerical tools tailored to the specific inquiry has been developed and employed

DUFTY J W

2012-01-11T23:59:59.000Z

398

Statistical atom: Some quantum improvements  

Science Journals Connector (OSTI)

The Thomas-Fermi model is improved by simultaneously introducing three different quantum corrections. The first concerns the nonlocality of quantum mechanics; we go beyond the von Weizscker approach by including arbitrary powers of the gradient of the single-particle potential. The second is a special treatment of the strongly bound electrons, which removes the incorrect statistical description of the vicinity of the nucleus. In the third we generalize Dirac's way of handling the exchange interaction by, again, including gradient effects to arbitrary order. All this is done in the framework of a "potential-functional method" and results in a new differential equation for the potential. The comparison of numerical results with both experimental and Hartree-Fock data for the mean-squared distance indicates a superiority of the new statistical theory over the Hartree-Fock theory, at least for the description of the outer reaches of the atom.

Berthold-Georg Englert and Julian Schwinger

1984-05-01T23:59:59.000Z

399

Quantum Confinement in Hydrogen Bond  

E-Print Network [OSTI]

In this work, the quantum confinement effect is proposed as the cause of the displacement of the vibrational spectrum of molecular groups that involve hydrogen bonds. In this approach the hydrogen bond imposes a space barrier to hydrogen and constrains its oscillatory motion. We studied the vibrational transitions through the Morse potential, for the NH and OH molecular groups inside macromolecules in situation of confinement (when hydrogen bonding is formed) and non-confinement (when there is no hydrogen bonding). The energies were obtained through the variational method with the trial wave functions obtained from Supersymmetric Quantum Mechanics (SQM) formalism. The results indicate that it is possible to distinguish the emission peaks related to the existence of the hydrogen bonds. These analytical results were satisfactorily compared with experimental results obtained from infrared spectroscopy.

Santos, Carlos da Silva dos; Ricotta, Regina Maria

2015-01-01T23:59:59.000Z

400

Feasible quantum engineering of quantum multiphoton superpositions  

E-Print Network [OSTI]

We examine an experimental setup implementing a family of quantum non-Gaussian filters. The filters can be applied to an arbitrary two-mode input state. We assume realistic photodetection in the filtering process and explore two different models of inefficient detection: a beam splitter of a small reflectivity located in front of a perfect detector and a Weierstrass transform applied to the unperturbed measurement outcomes. We explicitly give an operator which describes the coherent action of the filters in the realistic experimental conditions. The filtered states may find applications in quantum metrology, quantum communication and other quantum tasks.

Magdalena Stobi?ska

2014-09-03T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Hacking commercial quantum cryptography systems by tailored bright illumination  

E-Print Network [OSTI]

The peculiar properties of quantum mechanics allow two remote parties to grow a private, secret key, even if the eavesdropper can do anything permitted by the laws of nature. In quantum key distribution (QKD) the parties exchange non-orthogonal or entangled quantum states to generate quantum correlated classical data. Consequently, QKD implementations always rely on detectors to measure the relevant quantum property of the signal states. However, practical detectors are not only sensitive to quantum states. Here we show how an eavesdropper can exploit such deviations from the ideal behaviour: We demonstrate experimentally how the detectors in two commercially available QKD systems can be fully remote controlled using specially tailored bright illumination. This makes it possible to acquire the full secret key without leaving any trace; we propose an eavesdropping apparatus built of off-the-shelf components. The loophole is likely to be present in most QKD systems using avalanche photo diodes (APDs) to detect ...

Lydersen, Lars; Wittmann, Christoffer; Elser, Dominique; Skaar, Johannes; Makarov, Vadim; 10.1038/NPHOTON.2010.214

2010-01-01T23:59:59.000Z

402

Stochastic electrodynamics and the interpretation of quantum physics  

E-Print Network [OSTI]

Arguments are given for the plausibility that quantum mechanics is a stochastic theory and that many quantum phenomena derive from the existence of a real noise consisting of vacuum fluctuations of the fields existing in nature. I revisit stochastic electrodynamics (SED), a theory that studies classical systems of electrically charged particles immersed in a real electromagnetic zeropoint field with spectral density proportional to the cube of the frequency, Planck's constant appearing as the parameter fixing the scale. Asides from briefly reviewing known results, I make a detailed comparison between SED and quantum mechanics which shows that both theories make different predictions in many cases. However SED might be a guide for a stochastic interpretation of quantum mechanics

Emilio Santos

2014-10-02T23:59:59.000Z

403

Efficient distributed quantum computing  

E-Print Network [OSTI]

We provide algorithms for efficiently moving and addressing quantum memory in parallel. These imply that the standard circuit model can be simulated with a low overhead by a more realistic model of a distributed quantum ...

Beals, Robert

404

Redshifted and blueshifted photoluminescence emission of InAs/InP quantum dots upon amorphization of phase change material  

Science Journals Connector (OSTI)

We present the mechanisms underlying the redshifted and blueshifted photoluminescence (PL) of quantum dots (QDs) upon amorphization of phase change material (PCM). We calculated the...

Humam, Nurrul Syafawati Binti; Sato, Yu; Takahashi, Motoki; Kanazawa, Shohei; Tsumori, Nobuhiro; Regreny, Philippe; Gendry, Michel; Saiki, Toshiharu

2014-01-01T23:59:59.000Z

405

Electrically Confined Quantum Dot Intersubband Optoelectronic Devices Wei Wu, Dibyendu Dey, Omer G. Memis, Alex Katnelson, and *Hooman Mohseni  

E-Print Network [OSTI]

and optoelectronic devices, lasers and their applications. The Systems area focuses on wireless communication systems 361 Quantum Mechanics For Engineers ELEC 462 Optoelectronic Devices PHYS 302 Intermediate

Mohseni, Hooman

406

Changing quantum reference frames  

E-Print Network [OSTI]

We consider the process of changing reference frames in the case where the reference frames are quantum systems. We find that, as part of this process, decoherence is necessarily induced on any quantum system described relative to these frames. We explore this process with examples involving reference frames for phase and orientation. Quantifying the effect of changing quantum reference frames serves as a first step in developing a relativity principle for theories in which all objects including reference frames are necessarily quantum.

Matthew C. Palmer; Florian Girelli; Stephen D. Bartlett

2014-05-21T23:59:59.000Z

407

Quantum money from knots  

E-Print Network [OSTI]

Quantum money is a cryptographic protocol in which a mint can produce a quantum state, no one else can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint. We present a concrete quantum money scheme based on superpositions of diagrams that encode oriented links with the same Alexander polynomial. We expect our scheme to be secure against computationally bounded adversaries.

Edward Farhi; David Gosset; Avinatan Hassidim; Andrew Lutomirski; Peter Shor

2010-04-28T23:59:59.000Z

408

Nonequilibrium quantum kinetics  

SciTech Connect (OSTI)

This paper contains viewgraphs on non-equilibrium quantum kinetics of nuclear reactions at the intermediate and high energy ranges.

Danielewicz, P.

1997-09-22T23:59:59.000Z

409

Mechanical memory  

DOE Patents [OSTI]

A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.

Gilkey, Jeffrey C. (Albuquerque, NM); Duesterhaus, Michelle A. (Albuquerque, NM); Peter, Frank J. (Albuquerque, NM); Renn, Rosemarie A. (Albuquerque, NM); Baker, Michael S. (Albuquerque, NM)

2006-05-16T23:59:59.000Z

410

Mechanical memory  

DOE Patents [OSTI]

A first-in-first-out (FIFO) microelectromechanical memory apparatus (also termed a mechanical memory) is disclosed. The mechanical memory utilizes a plurality of memory cells, with each memory cell having a beam which can be bowed in either of two directions of curvature to indicate two different logic states for that memory cell. The memory cells can be arranged around a wheel which operates as a clocking actuator to serially shift data from one memory cell to the next. The mechanical memory can be formed using conventional surface micromachining, and can be formed as either a nonvolatile memory or as a volatile memory.

Gilkey, Jeffrey C. (Albuquerque, NM); Duesterhaus, Michelle A. (Albuquerque, NM); Peter, Frank J. (Albuquerque, NM); Renn, Rosemarie A. (Alburquerque, NM); Baker, Michael S. (Albuquerque, NM)

2006-08-15T23:59:59.000Z

411

Quantum money from knots  

E-Print Network [OSTI]

Quantum money is a cryptographic protocol in which a mint can produce a quantum state, no one else can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint. We present a concrete ...

Farhi, Edward

412

Efficient distributed quantum computing  

Science Journals Connector (OSTI)

...model of a distributed quantum computer. As a result, the circuit...algorithms and the way that quantum computers are likely to be implemented...W.H. was funded by NSF grant nos 0916400, 0829937, 0803478...Large scale modular quantum computer architecture with atomic memory...

2013-01-01T23:59:59.000Z

413

Topological Quantum Distillation  

E-Print Network [OSTI]

We construct a class of topological quantum codes to perform quantum entanglement distillation. These codes implement the whole Clifford group of unitary operations in a fully topological manner and without selective addressing of qubits. This allows us to extend their application also to quantum teleportation, dense coding and computation with magic states.

H. Bombin; M. A. Martin-Delgado

2006-05-16T23:59:59.000Z

414

Quantum Circuits Architecture  

E-Print Network [OSTI]

We present a method for optimizing quantum circuits architecture. The method is based on the notion of "quantum comb", which describes a circuit board in which one can insert variable subcircuits. The method allows one to efficiently address novel kinds of quantum information processing tasks, such as storing-retrieving, and cloning of channels.

Giulio Chiribella; Giacomo Mauro D'Ariano; Paolo Perinotti

2007-12-09T23:59:59.000Z

415

Eavesdropping without quantum memory  

E-Print Network [OSTI]

In quantum cryptography the optimal eavesdropping strategy requires that the eavesdropper uses quantum memories in order to optimize her information. What happens if the eavesdropper has no quantum memory? It is shown that the best strategy is actually to adopt the simple intercept/resend strategy.

H. Bechmann-Pasquinucci

2005-04-01T23:59:59.000Z

416

On the Nature of Quantum Phenomena  

E-Print Network [OSTI]

It is shown that a coherent understanding of all quantized phenomena, including those governed by unitary evolution equations as well as those related to irreversible quantum measurements, can be achieved in a scenario of successive nonequilibrium phase transitions, with the lowest hierarchy of these phase transitions occurring in a ``resonant cavity'' formed by the entire matter and energy content of the universe. In this formalism, the physical laws themselves are resonantly-selected and ordered in the universe cavity in a hierarchical manner, and the values of fundamental constants are determined through a Generalized Mach's Principle. The existence of a preferred reference frame in this scenario is shown to be consistent with the relational nature of the origin of physical laws. Covariant unitary evolution is shown to connect smoothly with the reduction of wavefunction in the preferred frame during quantum measurement. The superluminal nature of quantum processes in the lowest hierarchy coexists with the universal speed limit obeyed by processes in higher hierarchies. A natural quantum-to-classical transition is also obtained which is stable against the diffusive tendency of the unitary quantum evolution processes. In this formalism a realistic quasi-classical ontology is established for the foundations of quantum mechanics.

Xiaolei Zhang

2007-12-28T23:59:59.000Z

417

Quantum dynamics in the thermodynamic limit  

SciTech Connect (OSTI)

The description of spontaneous symmetry breaking that underlies the connection between classically ordered objects in the thermodynamic limit and their individual quantum-mechanical building blocks is one of the cornerstones of modern condensed-matter theory and has found applications in many different areas of physics. The theory of spontaneous symmetry breaking, however, is inherently an equilibrium theory, which does not address the dynamics of quantum systems in the thermodynamic limit. Here, we will use the example of a particular antiferromagnetic model system to show that the presence of a so-called thin spectrum of collective excitations with vanishing energy - one of the well-known characteristic properties shared by all symmetry-breaking objects - can allow these objects to also spontaneously break time-translation symmetry in the thermodynamic limit. As a result, that limit is found to be able, not only to reduce quantum-mechanical equilibrium averages to their classical counterparts, but also to turn individual-state quantum dynamics into classical physics. In the process, we find that the dynamical description of spontaneous symmetry breaking can also be used to shed some light on the possible origins of Born's rule. We conclude by describing an experiment on a condensate of exciton polaritons which could potentially be used to experimentally test the proposed mechanism.

Wezel, Jasper van [Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom)

2008-08-01T23:59:59.000Z

418

Generation and quantum control of giant plasmon pulses by transient quantum coherence  

E-Print Network [OSTI]

Amplified ultrashort laser pulses are useful in many fields of science and engineering. Pushing the frontiers of ultrashort pulse generation will lead to new applications in biomedical imaging, communications and sensing. We propose a new, quantum approach to ultrashort pulse generation using transient quantum coherence which predicts order of magnitude stronger pulses generated with lower input energy than in the steady-state regime, reducing the practical heating limitations. This femtosecond quantum-coherent analog of nanosecond Q-switching is not limited by the pulse duration constraints of the latter, and, in principle, may be used for a variety of lasers including x-ray and plasmon nanolasers. We apply this approach to generation of giant plasmon pulses and achieve quantum control of plasmon relaxation dynamics by varying the drive pulse delay, amplitude and duration. We provide insights into the control mechanisms, and discuss future implementations and applications of this new source of ultrashort nan...

Huo, Weiguang; Scully, Marlan

2014-01-01T23:59:59.000Z

419

Quantumness To Survive In An Evolutionary Environment  

SciTech Connect (OSTI)

An outlined subquantum theory that might be considered a possible extension of Bohmian mechanics is further discussed. In this theory a fundamental physical system is modelled as a particle endowed with a methodological probabilistic classical Turing machine, which characterizes systems as data processing devices, making of information a crucial physical concept in the determination of the system dynamics. The main idea of this theory resides in proposing a Darwinian evolutionary mechanism - therefore based on natural selection - as the central element that would determine the emergence of quantum mechanics from an evolutionarily stable strategy (ESS) whose essentials are supposedly captured in three regulating principles. The Darwinian character of these regulating principles is explored.

Baladron, Carlos [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, 47071 Valladolid (Spain)

2011-03-28T23:59:59.000Z

420

Quantum Physics and Nanotechnology  

E-Print Network [OSTI]

Experimental studies of infinite (unrestricted at least in one direction) quantum particle motion using probe nanotechnologies have revealed the necessity of revising previous concepts of their motion. Particularly, quantum particles transfer quantum motion nonlocality energy beside classical kinetic energy, in other words, they are in two different kinds of motion simultaneously. The quantum component of the motion energy may be quite considerable under certain circumstances. Some new effects were predicted and proved experimentally in terms of this phenomenon. A new prototype refrigerating device was tested, its principle of operation being based on the effect of transferring the quantum component of the motion energy.

Vladimir K. Nevolin

2011-06-06T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Dark Energy from Quantum Uncertainty of Remote Clocks  

E-Print Network [OSTI]

The observed cosmic acceleration was attributed to a mysterious dark energy in the framework of classical general relativity. The dark energy behaves very similar with vacuum energy in quantum mechanics. However, once the quantum effects are seriously taken into account, it predicts a complete wrong result and leads to a severe fine-tuning. To solve the problem, the exact meaning of time in quantum mechanics is reexamined. We abandon the standard interpretation that time is a global parameter in quantum mechanics, replace it by a quantum dynamical variable playing the role of physical clock. We find that synchronization of two spatially separated clocks can not be precisely realized at quantum level. There is an intrinsic quantum uncertainty of remote simultaneity, which implies an apparent vacuum energy fluctuation and gives an observed dark energy density $\\rho_{de}=\\frac{6}{\\pi}L_{P}^{-2}L_{H}^{-2}$ at leading order, where $L_{P}$ and $L_{H}$ are the Planck and Hubble scale cutoffs. The fraction of the dark energy is given by $\\Omega_{de}=\\frac{2}{\\pi}$ at leading order approximation, which does not evolve with time, so it is "always" comparable to the critical density. This theory is consistent with current cosmic observations.

M. J. Luo

2014-03-03T23:59:59.000Z

422

Quantum and classical dissipation of charged particles  

SciTech Connect (OSTI)

A Hamiltonian approach is presented to study the two dimensional motion of damped electric charges in time dependent electromagnetic fields. The classical and the corresponding quantum mechanical problems are solved for particular cases using canonical transformations applied to Hamiltonians for a particle with variable mass. Greens function is constructed and, from it, the motion of a Gaussian wave packet is studied in detail. -- Highlights: Hamiltonian of a damped charged particle in time dependent electromagnetic fields. Exact Greens function of a charged particle in time dependent electromagnetic fields. Time evolution of a Gaussian wave packet of a damped charged particle. Classical and quantum dynamics of a damped electric charge.

Ibarra-Sierra, V.G. [Departamento de Fsica, Universidad Autnoma Metropolitana at Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mxico D.F. (Mexico)] [Departamento de Fsica, Universidad Autnoma Metropolitana at Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mxico D.F. (Mexico); Anzaldo-Meneses, A.; Cardoso, J.L.; Hernndez-Saldaa, H. [rea de Fsica Terica y Materia Condensada, Universidad Autnoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 Mxico D.F. (Mexico)] [rea de Fsica Terica y Materia Condensada, Universidad Autnoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 Mxico D.F. (Mexico); Kunold, A., E-mail: akb@correo.azc.uam.mx [rea de Fsica Terica y Materia Condensada, Universidad Autnoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 Mxico D.F. (Mexico); Roa-Neri, J.A.E. [rea de Fsica Terica y Materia Condensada, Universidad Autnoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 Mxico D.F. (Mexico)] [rea de Fsica Terica y Materia Condensada, Universidad Autnoma Metropolitana at Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 Mxico D.F. (Mexico)

2013-08-15T23:59:59.000Z

423

Local models and EPR quantum correlations  

E-Print Network [OSTI]

A model for two entangled systems in an EPR setting is shown to reproduce the quantum-mechanical outcomes and expectation values. Each system is represented by a small sphere containing a point-like particle embedded in a field. A quantum state appears as an equivalence class of several possible particle-field configurations. Contrarily to Bell-type hidden variables models, the fields account for the non-commutative aspects of the measurements and deny the simultaneous reality of incompatible physical quantities, thereby allowing to escape EPR's ``completeness or locality'' dilemma.

A. Matzkin

2009-01-14T23:59:59.000Z

424

Success Stories: Quantum Dots  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Quantum Dots Outshine the Competition for Biomedical Assays Quantum Dots Outshine the Competition for Biomedical Assays Quantum Dots (Qdots), nano-scale semiconductor crystals that emit a range of bright colors when excited by a light source such as a laser, are shining brightly these days. The Berkeley Lab developed technology has been licensed by Quantum Dot Corporation and is being used as fluorescence probes for biomedical assays. The technology just won an R & D 100 Award and Quantum Dot Corporation was named by Fortune magazine as one of 2004's "Cool Companies." Science honored the technology as one of the Top 10 Breakthroughs of the Year in 2003, and Nanotechnology Now named Quantum Dots as the Best Nanotech Product in 2003, among other honors. Quantum Dot Corporation (QDC) is a 1998 start-up biotechnology company

425

Adiabatic topological quantum computing  

E-Print Network [OSTI]

Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.

Chris Cesare; Andrew J. Landahl; Dave Bacon; Steven T. Flammia; Alice Neels

2014-06-10T23:59:59.000Z

426

Adiabatic Quantum Transistors  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We describe a many-body quantum system that can be made to quantum compute by the adiabatic application of a large applied field to the system. Prior to the application of the field, quantum information is localized on one boundary of the device, and after the application of the field, this information propagates to the other side of the device, with a quantum circuit applied to the information. The applied circuit depends on the many-body Hamiltonian of the material, and the computation takes place in a degenerate ground space with symmetry-protected topological order. Such adiabatic quantum transistors are universal adiabatic quantum computing devices that have the added benefit of being modular. Here, we describe this model, provide arguments for why it is an efficient model of quantum computing, and examine these many-body systems in the presence of a noisy environment.

Bacon, Dave; Flammia, Steven T.; Crosswhite, Gregory M.

2013-06-01T23:59:59.000Z

427

Quantum Geometry and Black Holes  

E-Print Network [OSTI]

We present an overall picture of the advances in the description of black hole physics from the perspective of loop quantum gravity. After an introduction that discusses the main conceptual issues we present some details about the classical and quantum geometry of isolated horizons and their quantum geometry and then use this scheme to give a natural definition of the entropy of black holes. The entropy computations can be neatly expressed in the form of combinatorial problems solvable with the help of methods based on number theory and the use of generating functions. The recovery of the Bekenstein-Hawking law and corrections to it is explained in some detail. After this, due attention is paid to the discussion of semiclassical issues. An important point in this respect is the proper interpretation of the horizon area as the energy that should appear in the statistical-mechanical treatment of the black hole model presented here. The chapter ends with a comparison between the microscopic and semiclassical app...

G., J Fernando Barbero

2015-01-01T23:59:59.000Z

428

Smooth horizons and quantum ripples  

E-Print Network [OSTI]

Black Holes are unique objects which allow for meaningful theoretical studies of strong gravity and even quantum gravity effects. An infalling and a distant observer would have very different views on the structure of the world. However, a careful analysis has shown that it entails no genuine contradictions for physics, and the paradigm of observer complementarity has been coined. Recently this picture was put into doubt. In particular, it was argued that in old Black Holes a firewall must form in order to protect the basic principles of quantum mechanics. This AMPS paradox has already been discussed in a vast number of papers with different attitudes and conclusions. Here we want to argue that a possible source of confusion is neglection of quantum gravity effects. Contrary to widespread perception, it does not necessarily mean that effective field theory is inapplicable in rather smooth neighbourhoods of large Black Hole horizons. The real offender might be an attempt to consistently use it over the huge distances from the near-horizon zone of old Black Holes to the early radiation. We give simple estimates to support this viewpoint and show how the Page time and (somewhat more speculative) scrambling time do appear.

Alexey Golovnev

2014-02-12T23:59:59.000Z

429

Quantum Measurements: a modern view for quantum optics experimentalists  

E-Print Network [OSTI]

In these notes, based on lectures given as part of the Les Houches summer school on Quantum Optics and Nanophotonics in August, 2013, I have tried to give a brief survey of some important approaches and modern tendencies in quantum measurement. I wish it to be clear from the outset that I shy explicitly away from the "quantum measurement problem," and that the present treatment aims to elucidate the theory and practice of various ways in which measurements can, in light of quantum mechanics, be carried out; and various formalisms for describing them. While the treatment is by necessity largely theoretical, the emphasis is meant to be on an experimental "perspective" on measurement -- that is, to place the priority on the possibility of gaining information through some process, and then attempting to model that process mathematically and consider its ramifications, rather than stressing a particular mathematical definition as the {\\it sine qua non} of measurement. The textbook definition of measurement as being a particular set of mathematical operations carried out on particular sorts of operators has been so well drilled into us that many have the unfortunate tendency of saying "that experiment can't be described by projections onto the eigenstates of a Hermitian operator, so it is not really a measurement," when of course any practitioner of an experimental science such as physics should instead say "that experiment allowed us to measure something, and if the standard theory of measurement does not describe it, the standard theory of measurement is incomplete." Idealisations are important, but when the real world breaks the approximations made in the theory, it is the theory which must be fixed, and not the real world.

Aephraim M. Steinberg

2014-06-20T23:59:59.000Z

430

Computational mechanics  

SciTech Connect (OSTI)

The Computational Mechanics thrust area sponsors research into the underlying solid, structural and fluid mechanics and heat transfer necessary for the development of state-of-the-art general purpose computational software. The scale of computational capability spans office workstations, departmental computer servers, and Cray-class supercomputers. The DYNA, NIKE, and TOPAZ codes have achieved world fame through our broad collaborators program, in addition to their strong support of on-going Lawrence Livermore National Laboratory (LLNL) programs. Several technology transfer initiatives have been based on these established codes, teaming LLNL analysts and researchers with counterparts in industry, extending code capability to specific industrial interests of casting, metalforming, and automobile crash dynamics. The next-generation solid/structural mechanics code, ParaDyn, is targeted toward massively parallel computers, which will extend performance from gigaflop to teraflop power. Our work for FY-92 is described in the following eight articles: (1) Solution Strategies: New Approaches for Strongly Nonlinear Quasistatic Problems Using DYNA3D; (2) Enhanced Enforcement of Mechanical Contact: The Method of Augmented Lagrangians; (3) ParaDyn: New Generation Solid/Structural Mechanics Codes for Massively Parallel Processors; (4) Composite Damage Modeling; (5) HYDRA: A Parallel/Vector Flow Solver for Three-Dimensional, Transient, Incompressible Viscous How; (6) Development and Testing of the TRIM3D Radiation Heat Transfer Code; (7) A Methodology for Calculating the Seismic Response of Critical Structures; and (8) Reinforced Concrete Damage Modeling.

Goudreau, G.L.

1993-03-01T23:59:59.000Z

431

Generalized SAFT-DFT/DMT Model for the Thermodynamic, Interfacial, and Transport Properties of Associating Fluids:? Application for n-Alkanols  

Science Journals Connector (OSTI)

Generalized SAFT-DFT/DMT Model for the Thermodynamic, Interfacial, and Transport Properties of Associating Fluids:? Application for n-Alkanols ... We have developed a global crossover (GC) statistical associating fluid theory (SAFT) equation of state (EOS) for associating fluids that incorporates nonanalytic scaling laws in the critical region and in the limit of low densities, ? ? 0, is transformed into the ideal-gas equation EOS. ... Unlike the crossover SAFT EOS developed earlier, the new GC SAFT EOS contains a so-called kernel term and reproduces the asymptotic scaling behavior of the isochoric heat capacity in the one- and two-phase regions. ...

S. B. Kiselev; J. F. Ely; I. M. Abdulagatov; M. L. Huber

2005-07-02T23:59:59.000Z

432

The Quantum Field as a Quantum Computer  

E-Print Network [OSTI]

It is supposed that at very small scales a quantum field is an infinite homogeneous quantum computer. On a quantum computer the information cannot propagate faster than $c=a/\\tau$, $a$ and $\\tau$ being the minimum space and time distances between gates, respectively. It is shown that the information flow satisfies a Dirac equation, with speed $v=\\zeta c$ and $\\zeta=\\zeta(m)$ mass-dependent. For $a/\\tau=c$ the speed of light $\\zeta^{-1}$ is a vacuum refraction index increasing monotonically from $\\zeta^{-1}(0)=1$ to $\\zeta^{-1}(M)=\\infty$, $M$ being the Planck mass for $2a$ the Planck length.

Giacomo Mauro D'Ariano

2010-12-02T23:59:59.000Z

433

Hybrid Quantum Computation in Quantum Optics  

E-Print Network [OSTI]

We propose a hybrid quantum computing scheme where qubit degrees of freedom for computation are combined with quantum continuous variables for communication. In particular, universal two-qubit gates can be implemented deterministically through qubit-qubit communication, mediated by a continuous-variable bus mode ("qubus"), without direct interaction between the qubits and without any measurement of the qubus. The key ingredients are controlled rotations of the qubus and unconditional qubus displacements. The controlled rotations are realizable through typical atom-light interactions in quantum optics. For such interactions, our scheme is universal and works in any regime, including the limits of weak and strong nonlinearities.

P. van Loock; W. J. Munro; Kae Nemoto; T. P. Spiller; T. D. Ladd; Samuel L. Braunstein; G. J. Milburn

2007-01-11T23:59:59.000Z

434

Ab-initio study of structural, mechanical and electronic properties of functionalized carbon nanotubes  

SciTech Connect (OSTI)

We present exemplary results of extensive studies of structural, mechanical and electronic properties of covalent functionalization of carbon nanotubes (CNTs). We report new results for metallic (9,0), and semiconducting (10,0) single-wall carbon nanotubes (CNT) functionalized with -COOH, -OH, and both groups with concentration up to 12.5%. Our studies are performed in the framework of the density functional theory (DFT). We discuss here the stability, local and global changes in structure, elastic moduli (Young's, Shear, and Bulk), electronic structure and resulting band gaps, as a function of the density of the adsorbed molecules.

Milowska, Karolina Z.; Birowska, Magdalena; Majewski, Jacek A. [Faculty of Physics, University of Warsaw, ul. Hoza 69, 00-681 Warszawa (Poland)

2013-12-04T23:59:59.000Z

435

Theory of ballistic transport through a 3D-1D-3D quantum system  

Science Journals Connector (OSTI)

Ballistic transport through a three-dimensionalone-dimensionalthree-dimensional quantum system has been studied theoretically. Based on an exact quantum-mechanical formulation, the quantization of the conductance in units of 2e2/h of this vertical analog to the split-gate defined quantum channel in a two-dimensional electron gas has been proved. By taking into account the mode degeneracy in the lateral confined quantum pillar, multiple conductance plateaus, i.e., the conductance changes in steps of multiples of 2e2/h, are shown to appear in the quantum system.

Hongqi Xu

1993-09-15T23:59:59.000Z

436

MiniDFT  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

for bulk silicon, using the LDA functional and a 30 Ry plane-wave cutoff. mpirun -np 8 .minidft -in Si333.in > Si333.out The second test is a 2 x 2 x 2 super-cell for TiO2,...

437

Quantum Optomechanical Heat Engine  

E-Print Network [OSTI]

We investigate theoretically a quantum optomechanical realization of a heat engine. In a generic optomechanical arrangement the optomechanical coupling between the cavity field and the oscillating end-mirror results in polariton normal mode excitations whose character depends on the pump detuning and the coupling strength. By varying that detuning it is possible to transform their character from phonon-like to photon-like, so that they are predominantly coupled to the thermal reservoir of phonons or photons, respectively. We exploit the fact that the effective temperatures of these two reservoirs are different to produce a Otto cycle along one of the polariton branches. We discuss the basic properties of the system in two different regimes: in the optical domain it is possible to extract work from the thermal energy of a mechanical resonator at finite temperature, while in the microwave range one can in principle exploit the cycle to extract work from the blackbody radiation background coupled to an ultra-cold atomic ensemble.

Keye Zhang; Francesco Bariani; Pierre Meystre

2014-04-17T23:59:59.000Z

438

Mechanical Vibration  

Science Journals Connector (OSTI)

... THE suppression and control of mechanical vibration have assumed great importance in engineering. One consequence of this is that the number ... degree of emphasis is placed on transient oscillation (in addition to steady-State and free vibration). The treatment of this topic is based mainly on phase-plane constructions and it ...

R. E. D. BISHOP

1958-12-06T23:59:59.000Z

439

Quantum Copy-Protection and Quantum Money  

E-Print Network [OSTI]

Forty years ago, Wiesner proposed using quantum states to create money that is physically impossible to counterfeit, something that cannot be done in the classical world. However, Wiesner's scheme required a central bank ...

Aaronson, Scott

440

Generalized quantum defect methods in quantum chemistry  

E-Print Network [OSTI]

The reaction matrix of multichannel quantum defect theory, K, gives a complete picture of the electronic structure and the electron - nuclear dynamics for a molecule. The reaction matrix can be used to examine both bound ...

Altunata, Serhan

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Nested Quantum Walks with Quantum Data Structures  

E-Print Network [OSTI]

We develop a new framework that extends the quantum walk framework of Magniez, Nayak, Roland, and Santha, by utilizing the idea of quantum data structures to construct an efficient method of nesting quantum walks. Surprisingly, only classical data structures were considered before for searching via quantum walks. The recently proposed learning graph framework of Belovs has yielded improved upper bounds for several problems, including triangle finding and more general subgraph detection. We exhibit the power of our framework by giving a simple explicit constructions that reproduce both the $O(n^{35/27})$ and $O(n^{9/7})$ learning graph upper bounds (up to logarithmic factors) for triangle finding, and discuss how other known upper bounds in the original learning graph framework can be converted to algorithms in our framework. We hope that the ease of use of this framework will lead to the discovery of new upper bounds.

Stacey Jeffery; Robin Kothari; Frederic Magniez

2012-10-03T23:59:59.000Z

442

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic compounds. Working together, two British groups at the University of Edinburgh and the University of Manchester have bridged this gap with hybrid rotaxanes, in which inorganic rings encircle the organic axles. The hybrid architecture greatly increases their range of useful physical properties, such as the magnetism based on molecular magnets that may make them suitable as qubits for quantum computers.

443

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic compounds. Working together, two British groups at the University of Edinburgh and the University of Manchester have bridged this gap with hybrid rotaxanes, in which inorganic rings encircle the organic axles. The hybrid architecture greatly increases their range of useful physical properties, such as the magnetism based on molecular magnets that may make them suitable as qubits for quantum computers.

444

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic compounds. Working together, two British groups at the University of Edinburgh and the University of Manchester have bridged this gap with hybrid rotaxanes, in which inorganic rings encircle the organic axles. The hybrid architecture greatly increases their range of useful physical properties, such as the magnetism based on molecular magnets that may make them suitable as qubits for quantum computers.

445

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic compounds. Working together, two British groups at the University of Edinburgh and the University of Manchester have bridged this gap with hybrid rotaxanes, in which inorganic rings encircle the organic axles. The hybrid architecture greatly increases their range of useful physical properties, such as the magnetism based on molecular magnets that may make them suitable as qubits for quantum computers.

446

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic compounds. Working together, two British groups at the University of Edinburgh and the University of Manchester have bridged this gap with hybrid rotaxanes, in which inorganic rings encircle the organic axles. The hybrid architecture greatly increases their range of useful physical properties, such as the magnetism based on molecular magnets that may make them suitable as qubits for quantum computers.

447

Quantum Information: an invitation for mathematicians  

SciTech Connect (OSTI)

Quantum Information is the science that aims to use the unusual behavior of the microscopic world, governed by the laws of Quantum Mechanics, in order to improve the way in which we compute or communicate information. Though the first ideas in this direction come from the early 80's, it is in the last decade when Quantum Information has suffered an spectacular development. It is impossible to resume in a paper like this one the importance and complexity of the field. Therefore, I will limit to briefly explain some of the initial ideas (considered classical by now), and to briefly suggest some of the modern lines of research. By the nature of this exposition, I have decided to avoid rigor and to concentrate more in ideas and intuitions. Anyhow, I have tried to provide with enough references, in such a way that an interested reader could find there proper theorems and proofs.

Perez-Garcia, David [Departamento de Analisis Matematico. Universidad Complutense de Madrid. 28040 Madrid (Spain)

2009-05-06T23:59:59.000Z

448

Quantum Copy-Protection and Quantum Money  

E-Print Network [OSTI]

Forty years ago, Wiesner proposed using quantum states to create money that is physically impossible to counterfeit, something that cannot be done in the classical world. However, Wiesner's scheme required a central bank to verify the money, and the question of whether there can be unclonable quantum money that anyone can verify has remained open since. One can also ask a related question, which seems to be new: can quantum states be used as copy-protected programs, which let the user evaluate some function f, but not create more programs for f? This paper tackles both questions using the arsenal of modern computational complexity. Our main result is that there exist quantum oracles relative to which publicly-verifiable quantum money is possible, and any family of functions that cannot be efficiently learned from its input-output behavior can be quantumly copy-protected. This provides the first formal evidence that these tasks are achievable. The technical core of our result is a "Complexity-Theoretic No-Cloning Theorem," which generalizes both the standard No-Cloning Theorem and the optimality of Grover search, and might be of independent interest. Our security argument also requires explicit constructions of quantum t-designs. Moving beyond the oracle world, we also present an explicit candidate scheme for publicly-verifiable quantum money, based on random stabilizer states; as well as two explicit schemes for copy-protecting the family of point functions. We do not know how to base the security of these schemes on any existing cryptographic assumption. (Note that without an oracle, we can only hope for security under some computational assumption.)

Scott Aaronson

2011-10-24T23:59:59.000Z

449

Quantum computation of scattering in scalar quantum field theories  

Science Journals Connector (OSTI)

Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational ... Keywords: quantum algorithm, quantum field theory, simulation

Stephen P. Jordan, Keith S. M. Lee, John Preskill

2014-09-01T23:59:59.000Z

450

Quantum harmonic oscillator state synthesis by reservoir engineering  

E-Print Network [OSTI]

The robust generation of quantum states in the presence of decoherence is a primary challenge for explorations of quantum mechanics at larger scales. Using the mechanical motion of a single trapped ion, we utilize reservoir engineering to generate squeezed, coherent and displaced-squeezed states as steady states in the presence of noise. We verify the created state by generating two-state correlated spin-motion Rabi oscillations resulting in high contrast measurements. For both cooling and measurement, we use spin-oscillator couplings that provide transitions between oscillator states in an engineered Fock state basis. Our approach should facilitate studies of entanglement, quantum computation, and open-system quantum simulations in a wide range of physical systems.

D. Kienzler; H. -Y. Lo; B. Keitch; L. de Clercq; F. Leupold; F. Lindenfelser; M. Marinelli; V. Negnevitsky; J. P. Home

2015-01-16T23:59:59.000Z

451

Galilei covariance and Einstein's equivalence principle in quantum reference frames  

E-Print Network [OSTI]

The covariance of the Schr\\"odinger equation under Galilei boosts and the compatibility of nonrelativistic quantum mechanics with Einstein's equivalence principle have been constrained for so long to the existence of a superselection rule which would prevent a quantum particle to be found in superposition states of different masses. In a effort to avoid this expedient, thus allowing for nonrelativistic quantum mechanics to account for unstable particles, recent works have suggested that usual Galilean transformations are inconsistent with the nonrelativistic limit of the Lorentz transformation. Here we approach the issue in a fundamentally different way. Using a formalism of unitary transformations and employing quantum reference frames rather than immaterial coordinate systems, we show that the Schr\\"odinger equation, although form-variant, is fully compatible with the aforementioned principles of relativity.

S. T. Pereira; R. M. Angelo

2014-04-10T23:59:59.000Z

452

Black Holes, Entropies, and Semiclassical Spacetime in Quantum Gravity  

E-Print Network [OSTI]

We present a coherent picture of the quantum mechanics of black holes. The picture does not require the introduction of any drastically new physical effect beyond what is already known; it arises mostly from synthesizing and (re)interpreting existing results in appropriate manners. We identify the Bekenstein-Hawking entropy as the entropy associated with coarse-graining performed to obtain semiclassical field theory from a fundamental microscopic theory of quantum gravity. This clarifies the issues around the unitary evolution, the existence of the interior spacetime, and the thermodynamic nature in black hole physics--any result in semiclassical field theory is a statement about the maximally mixed ensemble of microscopic quantum states consistent with the specified background, within the precision allowed by quantum mechanics. We present a detailed analysis of information transfer in Hawking emission and black hole mining processes, clarifying what aspects of the underlying dynamics are (not) visible in sem...

Nomura, Yasunori

2014-01-01T23:59:59.000Z

453

Quantum harmonic oscillator state synthesis by reservoir engineering  

E-Print Network [OSTI]

The robust generation of quantum states in the presence of decoherence is a primary challenge for explorations of quantum mechanics at larger scales. Using the mechanical motion of a single trapped ion, we utilize reservoir engineering to generate squeezed, coherent and displaced-squeezed states as steady states in the presence of noise. We verify the created state by generating two-state correlated spin-motion Rabi oscillations resulting in high contrast measurements. For both cooling and measurement, we use spin-oscillator couplings that provide transitions between oscillator states in an engineered Fock state basis. Our approach should facilitate studies of entanglement, quantum computation, and open-system quantum simulations in a wide range of physical systems.

D. Kienzler; H. -Y. Lo; B. Keitch; L. de Clercq; F. Leupold; F. Lindenfelser; M. Marinelli; V. Negnevitsky; J. P. Home

2014-09-10T23:59:59.000Z

454

A graph-separation theorem for quantum causal models  

E-Print Network [OSTI]

A causal model is an abstract representation of a physical system as a directed acyclic graph (DAG), where the statistical dependencies are encoded using a graphical criterion called `d-separation'. Recent work by Wood & Spekkens shows that causal models cannot, in general, provide a faithful representation of quantum systems. Since d-separation encodes a form of Reichenbach's Common Cause Principle (RCCP), whose validity is questionable in quantum mechanics, we propose a generalised graph separation rule that does not assume the RCCP. We prove that the new rule faithfully captures the statistical dependencies between observables in a quantum network, encoded as a DAG, and is consistent with d-separation in a classical limit. We note that the resulting model is still unable to give a faithful representation of correlations stronger than quantum mechanics, such as the Popescu-Rorlich box.

Jacques Pienaar; Caslav Brukner

2014-10-31T23:59:59.000Z

455

Quantum Copy-Protection and Quantum Money  

E-Print Network [OSTI]

Forty years ago, Wiesner proposed using quantum states to create money that is physically impossible to counterfeit, something that cannot be done in the classical world. However, Wiesner's scheme required a central bank to verify the money, and the question of whether there can be unclonable quantum money that anyone can verify has remained open since. One can also ask a related question, which seems to be new: can quantum states be used as copy-protected programs, which let the user evaluate some function f, but not create more programs for f? This paper tackles both questions using the arsenal of modern computational complexity. Our main result is that there exist quantum oracles relative to which publicly-verifiable quantum money is possible, and any family of functions that cannot be efficiently learned from its input-output behavior can be quantumly copy-protected. This provides the first formal evidence that these tasks are achievable. The technical core of our result is a "Complexity-Theoretic No-Clon...

Aaronson, Scott

2011-01-01T23:59:59.000Z

456

Quantum Collapse and the Second Law of Thermodynamics  

E-Print Network [OSTI]

A heat engine undergoes a cyclic operation while in equilibrium with the net result of conversion of heat into work. Quantum effects such as superposition of states can improve an engine's efficiency by breaking detailed balance, but this improvement comes at a cost due to excess entropy generated from collapse of superpositions on measurement. We quantify these competing facets for a quantum ratchet comprised of an ensemble of pairs of interacting two-level atoms. We suggest that the measurement postulate of quantum mechanics is intricately connected to the second law of thermodynamics. More precisely, if quantum collapse is not inherently random, then the second law of thermodynamics can be violated. Our results challenge the conventional approach of simply quantifying quantum correlations as a thermodynamic work deficit.

Sahand Hormoz

2012-03-02T23:59:59.000Z

457

Quantum collapse and the second law of thermodynamics  

Science Journals Connector (OSTI)

A heat engine undergoes a cyclic operation while in equilibrium with the net result of conversion of heat into work. Quantum effects such as superposition of states can improve an engine's efficiency by breaking detailed balance, but this improvement comes at a cost due to excess entropy generated from collapse of superpositions on measurement. We quantify these competing facets for a quantum ratchet composed of an ensemble of pairs of interacting two-level atoms. We suggest that the measurement postulate of quantum mechanics is intricately connected to the second law of thermodynamics. More precisely, if quantum collapse is not inherently random, then the second law of thermodynamics can be violated. Our results challenge the conventional approach of simply quantifying quantum correlations as a thermodynamic work deficit.

Sahand Hormoz

2013-02-20T23:59:59.000Z

458

Nitrogen-tuned bonding mechanism of Li and Ti adatom embedded graphene  

SciTech Connect (OSTI)

The effects of nitrogen defects on the bonding mechanism and resultant binding energy between the metal and graphene layer were investigated using density functional theory (DFT) calculations. For the graphitic N-doped graphene, Li adatom exhibited ionic bonding character, while Ti adatom showed features of covalent bonding similar to that of pristine graphene. However, in the cases of pyridinic and pyrrolic structures, partially covalent bonding characteristic occurred around N atoms in the process of binding with metals, and this particular bond formation enhanced the bond strength of metal on the graphene layer as much as it exceeded the cohesive energy of the metal bulk. Thus, Li and Ti metals are expected to be dispersed with atomic accuracy on the pyridinic and pyrrolic N-doped graphene layers. These results demonstrate that the bonding mechanism of metalgraphene complex can change according to the type of N defect, and this also affects the binding results. - Graphical abstract: Display Omitted - Highlights: Nitrogen defects changed the bonding mechanism between metal and graphene. Bonding character and binding results were investigated using DFT calculations. Covalent bonding character occurred around pyridinic and pyrrolic N-doped graphene. Pyridinic and pyrrolic N atoms are effective for metal dispersion on the graphene.

Lee, Sangho; Chung, Yong-Chae, E-mail: yongchae@hanyang.ac.kr

2013-09-15T23:59:59.000Z

459

Electronic structure calculations of PbS quantum rods and tubes  

SciTech Connect (OSTI)

We study absorption spectra, optical and HOMO-LUMO gaps, and the density of states for PbS quantum rods (QRs) and tubes (QTs). We find some similarities and also differences in QR and QT properties. For both QRs and QTs, the optical and HOMO-LUMO gaps reach the plateaus for small lengths. We find that tubes are as stable as rods. The optical spectra exhibit a peak that can be due to the electron-hole interaction or be a prototype of an S{sub e}S{sub h} transition in the effective mass approximation. We also calculate the density of states by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The TDDFT density of states function is shifted towards the red side by 0.5?eV indicating the strong e-h interaction.

Pimachev, Artem; Dahnovsky, Yuri, E-mail: yurid@uwyo.edu [Department of Physics and Astronomy/3905, 1000 E. University Avenue, University of Wyoming Laramie, Wyoming 82071 (United States)

2014-01-28T23:59:59.000Z

460

Density functional theory (DFT) and ab initio molecular orbital calculations have been employed to determine the structures and energies of the isomers of the OH-toluene adduct, the methyl hydroxycyclohexadienyl radical, and their corresponding transitio  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Laboratory Investigation of Organic Aerosol Formation from Aromatic Hydrocarbons (DOE Award No. DE-FG02-02ER63098) Prepared by Luisa T. Molina, Renyi Zhang and Mario J. Molina Our work for this DOE funded project includes: (1) measurements of the kinetics and mechanism of the gas-phase oxidation reactions of the aromatic hydrocarbons initiated by OH; (2) measurements of aerosol formation from the aromatic hydrocarbons; and (3) theoretical studies to elucidate the OH-toluene reaction mechanism using quantum-chemical and rate theories. (1) Measurements of Gas-Phase Kinetics and Mechanism Work has been accomplished to develop laboratory instrumentation to conduct kinetic and mechanistic measurements of the aromatic hydrocarbon reactions initiated by OH, using

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Reducing Quantum Errors and Improving Large Scale Quantum Cryptography  

E-Print Network [OSTI]

Noise causes severe difficulties in implementing quantum computing and quantum cryptography. Several schemes have been suggested to reduce this problem, mainly focusing on quantum computation. Motivated by quantum cryptography, we suggest a coding which uses $N$ quantum bits ($N=n^2$) to encode one quantum bit, and reduces the error exponentially with $n$. Our result suggests the possibility of distributing a secure key over very long distances, and maintaining quantum states for very long times. It also provides a new quantum privacy amplification against a strong adversary.

T. Mor

1996-08-15T23:59:59.000Z

462

A Quantum Material Model of Static Schwarzschild Black Holes  

E-Print Network [OSTI]

A quantum-mechanical prescription of static Einstein field equation is proposed in order to construct the matter-metric eigen-states in the interior of a static Schwarzschild black hole where the signature of space-time is chosen as (--++). The spectrum of the quantum states is identified to be the integral multiples of the surface gravity. A statistical explanation of black hole entropy is given and a quantisation rule for the masses of Schwarzschild black holes is proposed.

S. -T. Sung

1997-03-16T23:59:59.000Z

463

Quantum Confinement in Hydrogen Bond of DNA and RNA  

E-Print Network [OSTI]

The hydrogen bond is a fundamental ingredient to stabilize the DNA and RNA macromolecules. The main contribution of this work is to describe quantitatively this interaction as a consequence of the quantum confinement of the hydrogen. The results for the free and confined system are compared with experimental data. The formalism to compute the energy gap of the vibration motion used to identify the spectrum lines is the Variational Method allied to Supersymmetric Quantum Mechanics.

Santos, da Silva dos; Ricotta, Regina Maria

2015-01-01T23:59:59.000Z

464

Quantum Money with Classical Verification  

E-Print Network [OSTI]

We construct a quantum money scheme that allows verification through classical communication with bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification.

Gavinsky, Dmitry

2011-01-01T23:59:59.000Z

465

Quantum-assisted biomolecular modelling  

Science Journals Connector (OSTI)

...incremental improvements. Quantum computing offers the possibility...might be addressed using quantum computation and speculate on the future importance of quantum-assisted biomolecular...self-organization and molecular motors are central to all cellular...

2010-01-01T23:59:59.000Z

466

Coherent control of quantum information  

E-Print Network [OSTI]

Quantum computation requires the ability to efficiently control quantum information in the presence of noise. In this thesis, NMR quantum information processors (QIPs) are used to study noise processes that compromise ...

Henry, Michael Kevin

2006-01-01T23:59:59.000Z

467

Instantaneous Quantum Computation  

E-Print Network [OSTI]

We examine theoretic architectures and an abstract model for a restricted class of quantum computation, called here instantaneous quantum computation because it allows for essentially no temporal structure within the quantum dynamics. Using the theory of binary matroids, we argue that the paradigm is rich enough to enable sampling from probability distributions that cannot, classically, be sampled from efficiently and accurately. This paradigm also admits simple interactive proof games that may convince a skeptic of the existence of truly quantum effects. Furthermore, these effects can be created using significantly fewer qubits than are required for running Shor's Algorithm.

Dan Shepherd; Michael J. Bremner

2008-09-04T23:59:59.000Z

468

Efficient Distributed Quantum Computing  

E-Print Network [OSTI]

We provide algorithms for efficiently addressing quantum memory in parallel. These imply that the standard circuit model can be simulated with low overhead by the more realistic model of a distributed quantum computer. As a result, the circuit model can be used by algorithm designers without worrying whether the underlying architecture supports the connectivity of the circuit. In addition, we apply our results to existing memory intensive quantum algorithms. We present a parallel quantum search algorithm and improve the time-space trade-off for the Element Distinctness and Collision problems.

Robert Beals; Stephen Brierley; Oliver Gray; Aram Harrow; Samuel Kutin; Noah Linden; Dan Shepherd; Mark Stather

2012-07-10T23:59:59.000Z

469

Rotational Quantum Friction  

E-Print Network [OSTI]

We investigate the frictional forces due to quantum fluctuations acting on a small sphere rotating near a surface. At zero temperature, we find the frictional force near a surface to be several orders of magnitude larger than that for the sphere rotating in vacuum. For metallic materials with typical conductivity, quantum friction is maximized by matching the frequency of rotation with the conductivity. Materials with poor conductivity are favored to obtain large quantum frictions. For semiconductor materials that are able to support surface plasmon polaritons, quantum friction can be further enhanced by several orders of magnitude due to the excitation of surface plasmon polaritons.

Rongkuo Zhao; Alejandro Manjavacas; F. Javier Garca de Abajo; J. B. Pendry

2012-08-21T23:59:59.000Z

470

Classical and Quantum Polyhedra  

E-Print Network [OSTI]

Quantum polyhedra constructed from angular momentum operators are the building blocks of space in its quantum description as advocated by Loop Quantum Gravity. Here we extend previous results on the semiclassical properties of quantum polyhedra. Regarding tetrahedra, we compare the results from a canonical quantization of the classical system with a recent wave function based approach to the large-volume sector of the quantum system. Both methods agree in the leading order of the resulting effective operator (given by an harmonic oscillator), while minor differences occur in higher corrections. Perturbative inclusion of such corrections improves the approximation to the eigenstates. Moreover, the comparison of both methods leads also to a full wave function description of the eigenstates of the (square of the) volume operator at negative eigenvalues of large modulus. For the case of general quantum polyhedra described by discrete angular momentum quantum numbers we formulate a set of quantum operators fulfilling in the semiclassical regime the standard commutation relations between momentum and position. Differently from previous formulations, the position variable here is chosen to have dimension of (Planck) length squared which facilitates the identification of quantum corrections. Finally, we provide expressions for the pentahedral volume in terms of Kapovich-Millson variables.

John Schliemann

2014-12-11T23:59:59.000Z

471

Terahertz Quantum Cascade Lasers  

Science Journals Connector (OSTI)

We provide an overview of terahertz quantum cascade lasers based on resonant-phonon depopulation and metal-metal waveguides, including two-phonon resonant-phonon depopulation...

Williams, Benjamin; Kumar, Sushil; Qin, Qi; Lee, Alan Wei Min; Hu, Qing; Reno, John L; Wasilewski, Z R; Liu, H C

472

Quantum Field Theory & Gravity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email...

473

Quantum Junction Solar Cells  

Science Journals Connector (OSTI)

Quantum Junction Solar Cells ... Department of Electrical and Computer Engineering, University of Toronto, 10 Kings College Road, Toronto, Ontario, M5S 3G4, Canada ...

Jiang Tang; Huan Liu; David Zhitomirsky; Sjoerd Hoogland; Xihua Wang; Melissa Furukawa; Larissa Levina; Edward H. Sargent

2012-08-10T23:59:59.000Z

474

Quantum random access memory  

E-Print Network [OSTI]

A random access memory (RAM) uses n bits to randomly address N=2^n distinct memory cells. A quantum random access memory (qRAM) uses n qubits to address any quantum superposition of N memory cells. We present an architecture that exponentially reduces the requirements for a memory call: O(log N) switches need be thrown instead of the N used in conventional (classical or quantum) RAM designs. This yields a more robust qRAM algorithm, as it in general requires entanglement among exponentially less gates, and leads to an exponential decrease in the power needed for addressing. A quantum optical implementation is presented.

Vittorio Giovannetti; Seth Lloyd; Lorenzo Maccone

2007-08-14T23:59:59.000Z

475

QUANTUM CONVERSION IN PHOTOSYNTHESIS  

E-Print Network [OSTI]

QUANTUM CONVERSION IN PHOTOSYNTHESIS Melvin Calvin Januaryas it occurs in modern photosynthesis can only take place inof the problem or photosynthesis, or any specific aspect of

Calvin, Melvin

2008-01-01T23:59:59.000Z

476

Quantum Markovian activated surface diffusion of interacting adsorbates  

E-Print Network [OSTI]

A quantum Markovian activated atom-surface diffusion model with interacting adsorbates is proposed for the intermediate scattering function, which is shown to be complex-valued and factorizable into a classical-like and a quantum-mechanical factor. Applications to the diffusion of Na atoms on flat (weakly corrugated) and corrugated-Cu(001) surfaces at different coverages and surface temperatures are analyzed. Quantum effects are relevant to diffusion at low surface temperatures and coverages even for relatively heavy particles, such as Na atoms, where transport by tunneling is absent.

R. Martinez-Casado; A. S. Sanz; S. Miret-Artes

2008-03-04T23:59:59.000Z

477

Is there a Jordan geometry underlying quantum physics?  

E-Print Network [OSTI]

There have been several propositions for a geometric and essentially non-linear formulation of quantum mechanics. From a purely mathematical point of view, the point of view of Jordan algebra theory might give new strength to such approaches: there is a ``Jordan geometry'' belonging to the Jordan part of the algebra of observables, in the same way as Lie groups belong to the Lie part. Both the Lie geometry and the Jordan geometry are well-adapted to describe certain features of quantum theory. We concentrate here on the mathematical description of the Jordan geometry and raise some questions concerning possible relations with foundational issues of quantum theory.

Wolfgang Bertram

2008-01-20T23:59:59.000Z

478

Quantum effects improve the energy efficiency of feedback control  

E-Print Network [OSTI]

The laws of thermodynamics apply equally well to quantum systems as to classical systems, and because of this quantum effects do not change the fundamental thermodynamic efficiency of isothermal refrigerators or engines. We show that, despite this fact, quantum mechanics permits measurement-based feedback control protocols that are more thermodynamically efficient than their classical counterparts. As part of our analysis we perform a detailed accounting of the thermodynamics of unitary feedback control, and elucidate the sources of inefficiency in measurement-based and coherent feedback.

Jordan M. Horowitz; Kurt Jacobs

2014-04-15T23:59:59.000Z

479

Quantum cosmology with varying speed of light: canonical approach  

E-Print Network [OSTI]

We investigate $(n+1)$--dimensional cosmology with varying speed of light. After solving corresponding Wheeler-DeWitt equation, we obtain exact solutions in both classical and quantum levels for ($c $--$\\Lambda$)--dominated Universe. We then construct the ``canonical'' wave packets which exhibit a good classical and quantum correspondence. We show that arbitrary but appropriate initial conditions lead to the same classical description. We also study the situation from de-Broglie Bohm interpretation of quantum mechanics and show that the corresponding Bohmian trajectories are in good agreement with the classical counterparts.

P. Pedram; S. Jalalzadeh

2007-12-16T23:59:59.000Z

480

Majorization-preserving quantum channels  

E-Print Network [OSTI]

In this report, we give a characterization to those quantum channels that preserve majorization relationship between quantum states. Some remarks are presented as well.

Lin Zhang

2012-09-24T23:59:59.000Z

Note: This page contains sample records for the topic "dft quantum mechanics" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

The Quantum Side of Photosynthesis  

Science Journals Connector (OSTI)

The Quantum Side of Photosynthesis ... But evidence is mounting that photosynthetic organisms may, in fact, capitalize on quantum effects to harness the suns rays. ...

JYLLIAN KEMSLEY

2012-02-19T23:59:59.000Z

482

Macroscopic quantum superposition of spin ensembles with ultra-long coherence times via superradiant masing  

E-Print Network [OSTI]

Macroscopic quantum phenomena such as lasers, Bose-Einstein condensates, superfluids, and superconductors are of great importance in foundations and applications of quantum mechanics. In particular, quantum superposition of a large number of spins in solids is highly desirable for both quantum information processing and ultrasensitive magnetometry. Spin ensembles in solids, however, have rather short collective coherence time (typically less than microseconds). Here we demonstrate that under realistic conditions it is possible to maintain macroscopic quantum superposition of a large spin ensemble (such as about ~10^{14} nitrogen-vacancy center electron spins in diamond) with an extremely long coherence time ~10^8 sec under readily accessible conditions. The scheme, following the mechanism of superradiant lasers, is based on superradiant masing due to coherent coupling between collective spin excitations (magnons) and microwave cavity photons. The coherence time of the macroscopic quantum superposition is the ...

Jin, Liang; Wrachtrup, Jrg; Liu, Ren-Bao

2014-01-01T23:59:59.000Z

483

Optimal quantum control using randomized benchmarking  

E-Print Network [OSTI]

We present a method for optimizing quantum control in experimental systems, using a subset of randomized benchmarking measurements to rapidly infer error. This is demonstrated to improve single- and two-qubit gates, minimize gate bleedthrough, where a gate mechanism can cause errors on subsequent gates, and identify control crosstalk in superconducting qubits. This method is able to correct parameters to where control errors no longer dominate, and is suitable for automated and closed-loop optimization of experimental systems.

J. Kelly; R. Barends; B. Campbell; Y. Chen; Z. Chen; B. Chiaro; A. Dunsworth; A. G. Fowler; I. -C. Hoi; E. Jeffrey; A. Megrant; J. Mutus; C. Neill; P. J. J. O`Malley; C. Quintana; P. Roushan; D. Sank; A. Vainsencher; J. Wenner; T. C. White; A. N. Cleland; John M. Martinis

2014-03-01T23:59:59.000Z

484

Quantum Probability and Decision Theory, Revisited  

E-Print Network [OSTI]

An extended analysis is given of the program, originally suggested by Deutsch, of solving the probability problem in the Everett interpretation by means of decision theory. Deutsch's own proof is discussed, and alternatives are presented which are based upon different decision theories and upon Gleason's Theorem. It is argued that decision theory gives Everettians most or all of what they need from `probability'. Some consequences of (Everettian) quantum mechanics for decision theory itself are also discussed.

David Wallace

2002-11-18T23:59:59.000Z

485

Harnessing vacuum forces for quantum sensing of graphene motion  

E-Print Network [OSTI]

Position measurements at the quantum level are vital for many applications, but also challenging. Typically, methods based on optical phase shifts are used, but these methods are often weak and difficult to apply to many materials. An important example is graphene, which is an excellent mechanical resonator due to its small mass and an outstanding platform for nanotechnologies, but is largely transparent. Here, we present a novel detection scheme based upon the strong, dispersive vacuum interactions between a graphene sheet and a quantum emitter. In particular, the mechanical displacement causes strong changes in the vacuum-induced shifts of the transition frequency of the emitter, which can be read out via optical fields. We show that this enables strong quantum squeezing of the graphene position on time scales short compared to the mechanical period.

Christine A. Muschik; Simon Moulieras; Adrian Bachtold; Maciej Lewenstein; Frank Koppens; Darrick Chang

2014-05-26T23:59:59.000Z

486

Quantum motor and future  

E-Print Network [OSTI]

In a popular language, the possibilities of the Casimir expulsion effect are presented, which can be the basis of quantum motors. Such motors can be in the form of a special multilayer thin film with periodic and complex nanosized structures. Quantum motors of the type of the Casimir platforms can be the base of transportation, energy and many other systems in the future.

Fateev, Evgeny G

2013-01-01T23:59:59.000Z

487

Quantum motor and future  

E-Print Network [OSTI]

In a popular language, the possibilities of the Casimir expulsion effect are presented, which can be the basis of quantum motors. Such motors can be in the form of a special multilayer thin film with periodic and complex nanosized structures. Quantum motors of the type of the Casimir platforms can be the base of transportation, energy and many other systems in the future.

Evgeny G. Fateev

2013-01-20T23:59:59.000Z

488

Isotope - based Quantum Information  

E-Print Network [OSTI]

This paper is brief review of three aspects of the isotope - based quantum information: computation, teleportation and cryptography. Our results demonstrate not only that entanglement exists in elementary excitation of isotope - mixed solids but also it can be used for quantum information processing.

Vladimir G. Plekhanov

2009-09-04T23:59:59.000Z

489

Reliable quantum computers  

Science Journals Connector (OSTI)

...the performance of a useful quantum computer will need to be. And that in itself...by the Department of Energy under Grant No. DE- FG03-92-ER40701, and...Lond. A (1998) Reliable quantum computers 409 References Aharonov, D. & Ben-Or...

1998-01-01T23:59:59.000Z

490

Quantum Spacetime Phenomenology  

E-Print Network [OSTI]

I review the current status of phenomenological programs inspired by quantum-spacetime research. I stress in particular the significance of results establishing that certain data analyses provide sensitivity to effects introduced genuinely at the Planck scale. And my main focus is on phenomenological programs that managed to affect the directions taken by studies of quantum-spacetime theories.

Giovanni Amelino-Camelia

2013-06-18T23:59:59.000Z