While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

1

High speed optical quantum random number generation

High speed optical quantum random number generation Martin FÂ¨urst1,2,, Henning Weier1,2, Sebastian, ready-for-use quantum random number generator (QRNG) whose stochastic model is based on the ran- domness directly delivered to a PC, generated at a rate of up to 50 Mbit/s, clearly pass all tests relevant

Weinfurter, Harald

2

Matter Waves and Orbital Quantum Numbers

The atom's orbital electron structure in terms of quantum numbers (principal, azimuthal, magnetic and spin) results in space for a maximum of: 2 electrons in the n=1 orbit, 8 electrons in the n=2 orbit, 18 electrons in the n=3 orbit, and so on. Those dispositions are correct, but that is not because of quantum numbers nor angular momentum nor a "Pauli exclusion principle". Matter waves were discovered in the early 20th century from their wavelength, which was predicted by DeBroglie to be, Planck's constant divided by the particle's momentum. But, the failure to obtain a reasonable theory for the matter wave frequency resulted in loss of interest. That problem is resolved in "A Reconsideration of Matter Waves" in which a reinterpretation of Einstein's derivation of relativistic kinetic energy [which produced his famous E = mc^2] leads to a valid matter wave frequency and a new understanding of particle kinetics and the atom's stable orbits. It is analytically shown that the orbital electron arrangement is enforced by the necessity of accommodating the space that each orbiting electron's matter wave occupies.

Roger Ellman

2005-05-18T23:59:59.000Z

3

transport of ions and polar molecules across biological membranes is essential for normal cell function synthetic transporters shown to be active in both model bilayers and cellular membranes. Mechanism of ion simulations of unassisted Na+ and ClÂ ion transport across a bilayer membrane. As the ion enters the outer

Smith, Bradley D.

4

Determination of the X(3872) Meson Quantum Numbers

The quantum numbers of the X(3872) meson are determined to be J[superscript PC]=1[superscript ++] based on angular correlations in B[superscript +]?X(3872)K[superscript +] decays, where X(3872)??[superscript +]?[superscript ...

Williams, Michael

5

Is there quantum chaos in the prime numbers?

A statistical analysis of the prime numbers indicates possible traces of quantum chaos. We have computed the nearest neighbor spacing distribution, number variance, skewness, and excess for sequences of the first N primes for various values of N. All four statistical measures clearly show a transition from random matrix statistics at small N toward Poisson statistics at large N. In addition, the number variance saturates at large lengths as is common for eigenvalue sequences. This data can be given a physical interpretation if the primes are thought of as eigenvalues of a quantum system whose classical dynamics is chaotic at low energy but regular at high energy. We discuss some difficulties with this interpretation in an attempt to clarify what kind of physical system might have the primes as its quantum eigenvalues.

Todd Timberlake; Jeffery Tucker

2007-08-19T23:59:59.000Z

6

Quantum random-number generator based on a photon-number-resolving detector

Science Journals Connector (OSTI)

We demonstrated a high-efficiency quantum random number generator which takes inherent advantage of the photon number distribution randomness of a coherent light source. This scheme was realized by comparing the photon flux of consecutive pulses with a photon number resolving detector. The random bit generation rate could reach 2.4 MHz with a system clock of 6.0 MHz, corresponding to a random bit generation efficiency as high as 40%. The random number files passed all the stringent statistical tests.

Min Ren; E Wu; Yan Liang; Yi Jian; Guang Wu; Heping Zeng

2011-02-23T23:59:59.000Z

7

Quantum random number generator based on spin noise

Science Journals Connector (OSTI)

We present an implementation of a robust quantum random number generator based on the quantum fluctuations of the collective spin of an alkali-metal vapor. The achieved bit rate is limited by the spin relaxation rate of the alkali-metal atoms 1/T2 to about 1 kbit/s. However, the same physical scheme, which is impervious to limitations posed by single-photon detectors used in current implementations and rests solely on threshold detection, can be extended to solid state systems with a bit rate higher than 1 Gbit/s.

G. E. Katsoprinakis; M. Polis; A. Tavernarakis; A. T. Dellis; I. K. Kominis

2008-05-19T23:59:59.000Z

8

Fast quantum-optical random-number generators

Science Journals Connector (OSTI)

In this paper we study experimentally the properties of three types of quantum -optical random-number generators and characterize them using the available National Institute for Standards and Technology statistical tests, as well as four alternate tests. The generators are characterized by a trade-off between, on one hand, the rate of generation of random bits and, on the other hand, the degree of randomness of the series which they deliver. We describe various techniques aimed at maximizing this rate without diminishing the quality (degree of randomness) of the series generated by it.

Thomas Durt; Carlos Belmonte; Louis-Philippe Lamoureux; Krassimir Panajotov; Frederik Van den Berghe; Hugo Thienpont

2013-02-25T23:59:59.000Z

9

Quantum breathers in capacitively coupled Josephson junctions: Correlations, number conservation coupled Josephson junctions. In the classical case the equations of motion admit discrete breather by employing the already developed tech- niques for quantum information processing using Josephson junctions

Flach, Sergej

10

PHYSICAL REVIEW A 87, 022339 (2013) Fast quantum-optical random-number generators

PHYSICAL REVIEW A 87, 022339 (2013) Fast quantum-optical random-number generators Thomas Durt,1 types of quantum -optical random-number generators and characterize them using the available National Institute for Standards and Technology statistical tests, as well as four alternate tests. The generators

Cerf, Nicolas

11

Postprocessing for quantum random-number generators: Entropy evaluation and randomness extraction

Science Journals Connector (OSTI)

Quantum random-number generators (QRNGs) can offer a means to generate information-theoretically provable random numbers, in principle. In practice, unfortunately, the quantum randomness is inevitably mixed with classical randomness due to classical noises. To distill this quantum randomness, one needs to quantify the randomness of the source and apply a randomness extractor. Here, we propose a generic framework for evaluating quantum randomness of real-life QRNGs by min-entropy, and apply it to two different existing quantum random-number systems in the literature. Moreover, we provide a guideline of QRNG data postprocessing for which we implement two information-theoretically provable randomness extractors: Toeplitz-hashing extractor and Trevisan's extractor.

Xiongfeng Ma; Feihu Xu; He Xu; Xiaoqing Tan; Bing Qi; Hoi-Kwong Lo

2013-06-21T23:59:59.000Z

12

Random Number Generation for Petascale Quantum Monte Carlo

The quality of random number generators can affect the results of Monte Carlo computations, especially when a large number of random numbers are consumed. Furthermore, correlations present between different random number streams in a parallel computation can further affect the results. The SPRNG software, which the author had developed earlier, has pseudo-random number generators (PRNGs) capable of producing large numbers of streams with large periods. However, they had been empirically tested on only thousand streams earlier. In the work summarized here, we tested the SPRNG generators with over a hundred thousand streams, involving over 10^14 random numbers per test, on some tests. We also tested the popular Mersenne Twister. We believe that these are the largest tests of PRNGs, both in terms of the numbers of streams tested and the number of random numbers tested. We observed defects in some of these generators, including the Mersenne Twister, while a few generators appeared to perform well. We also corrected an error in the implementation of one of the SPRNG generators.

Ashok Srinivasan

2010-03-16T23:59:59.000Z

13

Photon-number-resolved heralded-photon source for improved quantum key distribution

We have suppressed multiphoton probability of a heralded-photon source, which is vital for quantum key distribution with a higher secure key generation rate. It is accomplished by utilizing a practical photon-number-resolving detector for triggering resulting in an important step for improved practical quantum key distribution. Heralded-photon source and a practical photon-number-resolving detector capable of real-time processed multiphoton rejection are stably operable at room temperature and enable us to generate a secure key at a distance as long as an ideal single photon source is used.

Horikiri, Tomoyuki [Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Institute of Laser Science and Department of Applied Physics and Chemistry, University of Telecommunications, Chofu-ga-oka 1-5-1, Chofu, Tokyo 182-8585 (Japan); Takeno, Yuishi [Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Yabushita, Atsushi [Department of Electrophysics, Faculty of Science, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 300 (China); Kobayashi, Takayoshi [ICORP, JST, 4-1-8 Honcho, Kawaguchi, Saitama (Japan); Institute of Laser Science and Department of Applied Physics and Chemistry, University of Telecommunications, Chofu-ga-oka 1-5-1, Chofu, Tokyo 182-8585 (Japan); Department of Electrophysics, Faculty of Science, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 300 (China); Institute of Laser Engineering, Osaka University, Yamadagaoka 2-6, Suita, Osaka 565-0871 (Japan)

2007-07-15T23:59:59.000Z

14

We discuss methods of quantum state tomography for solid-state systems with a large nuclear spin $I=3/2$ in nanometer-scale semiconductors devices based on a quantum well. Due to quadrupolar interactions, the Zeeman levels of these nuclear-spin devices become nonequidistant, forming a controllable four-level quantum system (known as quartit or ququart). The occupation of these levels can be selectively and coherently manipulated by multiphoton transitions using the techniques of nuclear magnetic resonance (NMR) [Yusa et al., Nature (London) 434, 101 (2005)]. These methods are based on an unconventional approach to NMR, where the longitudinal magnetization $M_z$ is directly measured. This is in contrast to the standard NMR experiments and tomographic methods, where the transverse magnetization $M_{xy}$ is detected. The robustness against errors in the measured data is analyzed by using condition numbers. We propose several methods with optimized sets of rotations. The optimization is applied to decrease the number of NMR readouts and to improve the robustness against errors, as quantified by condition numbers. An example of state reconstruction, using Monte Carlo methods, is presented. Tomographic methods for quadrupolar nuclei with higher-spin numbers (including $I=7/2$) are also described.

Adam Miranowicz; Sahin K. Ozdemir; Jiri Bajer; Go Yusa; Nobuyuki Imoto; Yoshiro Hirayama; Franco Nori

2014-10-09T23:59:59.000Z

15

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 Â» 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

16

A High Speed, Post-Processing Free, Quantum Random Number Generator

A quantum random number generator (QRNG) based on gated single photon detection of an InGaAs photodiode at GHz frequency is demonstrated. Owing to the extremely long coherence time of each photon, each photons' wavefuntion extends over many gating cycles of the photodiode. The collapse of the photon wavefunction on random gating cycles as well as photon random arrival time detection events are used to generate sequences of random bits at a rate of 4.01 megabits/s. Importantly, the random outputs are intrinsically bias-free and require no post-processing procedure to pass random number statistical tests, making this QRNG an extremely simple device.

J. F. Dynes; Z. L. Yuan; A. W. Sharpe; A. J. Shields

2008-07-25T23:59:59.000Z

17

We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.

Nie, You-Qi; Zhang, Jun, E-mail: zhangjun@ustc.edu.cn; Pan, Jian-Wei [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Hong-Fei; Wang, Jian [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhen; Ma, Xiongfeng [Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084 (China)

2014-02-03T23:59:59.000Z

18

Office of Legacy Management (LM)

' ' , /v-i 2 -i 3 -A, This dow'at consists ~f--~-_,_~~~p.~,::, Number -------of.-&--copies, 1 Series.,-a-,-. ! 1 THE UNIVERSITY OF ROCHESTER 1; r-.' L INTRAMURALCORRESPONDENCE i"ks' 3 2.. September 25, 1947 Memo.tor Dr. A. H, Dovdy . From: Dr. H. E, Stokinger Be: Trip Report - Mayvood Chemical Works A trip vas made Nednesday, August 24th vith Messrs. Robert W ilson and George Sprague to the Mayvood Chemical F!orks, Mayvood, New Jersey one of 2 plants in the U.S.A. engaged in the production of thorium compounds. The purpose of the trip vas to: l 1. Learn the type of chemical processes employed in the thorium industry (thorium nitrate). 2. Survey conditions of eeosure of personnel associated vith these chemical processes. 3. Obtain samples of atmospheric contaminants in the plant, as

19

Science Journals Connector (OSTI)

The 100% polarized photon beam at the high intensity ? ray source (HI?S) at Duke University has been used to determine the parity of six dipole excitations between 2.9 and 3.6 MeV in the deformed nuclei Yb172,174 in photon scattering (??,?') experiments. The measured parities are compared with previous assignments based on the K quantum number that had been assigned in nuclear resonance fluorescence (NRF) experiments by using the Alaga rules. A systematic survey of the relation between ?-decay branching ratios and parity quantum numbers is given for the rare earth nuclei.

D. Savran; S. Müller; A. Zilges; M. Babilon; M. W. Ahmed; J. H. Kelley; A. Tonchev; W. Tornow; H. R. Weller; N. Pietralla; J. Li; I. V. Pinayev; Y. K. Wu

2005-03-08T23:59:59.000Z

20

Atomic and Molecular Quantum Theory Course Number: C561 23 The Born-Oppenheimer approximation are required. One powerful approximation is called the Born-Oppenheimer approximation. (It does have some limitations and we will discuss these as well.) The Born-Oppenheimer approximation assumes that the nuclei

Iyengar, Srinivasan S.

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

21

PHYSICAL RKVIE W A VOLUME 9, NUMBER 2 FEBRUARY 1974 Caialr3 waves in a quantum liquid

PHYSICAL RKVIE W A VOLUME 9, NUMBER 2 FEBRUARY 1974 CaialÂ»r3 waves in a quantum liquid George F- ing the hydrodynamic equation of Gross. ' He de- rives the pair of equations 9--R =-VR' VS --HARV as follows: #12;820 GEORGE F. BERTSCH moves infinitesimally in the z direction, with an amplitude

Bertsch George F.

22

Wesson obtained a limit on quantum and gravitational mass in the universe by combining the cosmological constant Lambda, Planck constant, the speed of light c, and also the gravitational constant G. The corresponding masses are 2.0x10E-62 kg and 2.3E+54 kg respectively, and in general can be obtained with the help of a generic dimensional analysis, or from an analysis where the cosmological constant appears in a four dimensional space-time and as a result of a higher dimensional reduction. In this paper our goal is to establish a relation for both quantum and gravitational mass as function of the information number bit N. For this reason, we first derive an expression for the cosmological constant as a function of information bit, since both masses depend on it, and then various resulting relations are explored, in relation to information number of bits N. Fractional information bits imply no information extraction is possible. We see, that the order of magnitude of the various parameters as well as their ratios involve the large number 10E+122, that is produced naturally from the fundamental parameters of modern cosmology. Finally, we propose that in a complete quantum gravity theory the idea of information the might have to be included, with the quantum bits of information (q-bits) as one of its fundamental parameters, resulting thus to a more complete understanding of the universe, its laws, and its evolution.

Ioannis Haranas; Ioannis Gkigkitzis

2014-06-09T23:59:59.000Z

23

The majority of Quantum Random Number Generators (QRNG) are designed as converters of a continuous quantum random variable into a discrete classical random bit value. For the resulting random bit sequence to be minimally biased, the conversion process demands an experimenter to fully characterize the underlying quantum system and implement parameter estimation routines. Here we show that conventional approaches to parameter estimation (such as e.g. {\\it Maximum Likelihood Estimation}) used on a finite QRNG data sample without caution may introduce binning bias and lead to overestimation of the randomness of the QRNG output. To bypass these complications, we develop an alternative conversion approach based on the Bayesian statistical inference method. We illustrate our approach using experimental data from a time-of-arrival QRNG and numerically simulated data from a vacuum homodyning QRNG. Side-by-side comparison with the conventional conversion technique shows that our method provides an automatic on-line bias control and naturally bounds the best achievable QRNG bit rate for a given measurement record.

Pavel Lougovski; Raphael Pooser

2014-04-23T23:59:59.000Z

24

Jack polynomials as fractional quantum Hall states and the Betti numbers of the (k+1)-equals ideal

We show that for Jack parameter \\alpha = -(k+1)/(r-1), certain Jack polynomials studied by Feigin-Jimbo-Miwa-Mukhin vanish to order r when k+1 of the coordinates coincide. This result was conjectured by Bernevig and Haldane, who proposed that these Jack polynomials are model wavefunctions for fractional quantum Hall states. Special cases of these Jack polynomials include the wavefunctions of Laughlin and Read-Rezayi. In fact, along these lines we prove several vanishing theorems known as clustering properties for Jack polynomials in the mathematical physics literature, special cases of which had previously been conjectured by Bernevig and Haldane. Motivated by the method of proof, which in case r = 2 identifies the span of the relevant Jack polynomials with the S_n-invariant part of a unitary representation of the rational Cherednik algebra, we conjecture that unitary representations of the type A Cherednik algebra have graded minimal free resolutions of Bernstein-Gelfand-Gelfand type; we prove this for the ideal of the (k+1)-equals arrangement in the case when the number of coordinates n is at most 2k+1. In general, our conjecture predicts the graded S_n-equivariant Betti numbers of the ideal of the (k+1)-equals arrangement with no restriction on the number of ambient dimensions.

Christine Berkesch Zamaere; Stephen Griffeth; Steven V Sam

2013-03-18T23:59:59.000Z

25

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

26

Science Journals Connector (OSTI)

Starting from Rules A and B of a previous paper (I), it is shown that the grand partition function can be evaluated in terms of the statistical averages of the occupation number in momentum space. The final formulation is in terms of a simple variational principle. The procedure represents a concise and complete separation of the effect of the Bose-Einstein or Fermi-Dirac statistical character of the particles from the dynamical problem. In the case of Bose statistics, this formulation makes possible a systematic computation of all thermodynamic functions near the Bose-Einstein transition point in the gaseous phase. Applications to a system of hard spheres are discussed.

T. D. Lee and C. N. Yang

1960-01-01T23:59:59.000Z

27

Polarization preserving quantum nondemolition photodetector

A polarization preserving quantum nondemolition photodetector is proposed based on nonlinearities obtainable through quantum coherence effects. An atomic level scheme is devised such that in the presence of strong linearly polarized drive field a coherent weak probe field acquires a phase proportional to the number of photons in the signal mode immaterial of its polarization state. It is also shown that the unavoidable phase-kicks resulting due to the measurement process are insensitive to the polarization state of the incoming signal photon. It is envisioned that such a device would have tremendous applicability in photonic quantum information proposals where quantum information in the polarization qubit is to be protected.

K. T. Kapale

2006-03-30T23:59:59.000Z

28

A collective photon-number-splitting attack strategy is proposed, which combines photon-number-splitting attack with an unambiguous set discrimination of quantum state. Verified by this attack strategy, it is shown that a two-way quantum secure direct communication protocol with qubits is insecure in real circumstance. Finally, we present a possible improved version of this kind of quantum secure direct communication protocol.

Lin Song [State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Mathematics and Computer Science, Fujian Normal University, Fuzhou 350007 (China); Wen Qiaoyan; Gao Fei [State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Zhu Fuchen [National Laboratory for Modern Communications, P.O. Box 810, Chengdu 610041 (China)

2009-05-15T23:59:59.000Z

29

41JUNE 2005AMERICAN METEOROLOGICAL SOCIETY | (not shown). This warm,

41JUNE 2005AMERICAN METEOROLOGICAL SOCIETY | (not shown). This warm, southerly flow accelerates to intense solar radiation, which lead to an early onset of melt. Therefore, an early and pro- longed meltW South 2004 (1), 2003 (2) Egedesminde 68.7ÂºN, 52.8ÂºW Central west 2004 (2), 2003 (1) Tasiilaq 65.6ÂºN, 37

Box, Jason E.

30

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

31

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

32

Quantum Mechanics, Group Theory, and C60 Frank Rioux

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

33

Quantum corrections to nonlinear ion acoustic wave with Landau damping

Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter ?{sub 1}=?(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=?{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.

Mukherjee, Abhik; Janaki, M. S. [Saha Institute of Nuclear Physics, Calcutta (India); Bose, Anirban [Serampore College, West Bengal (India)

2014-07-15T23:59:59.000Z

34

A Simplified Hierarchical Dynamic Quantum Secret Sharing Protocol with Added Features

Generalizing the notion of dynamic quantum secret sharing (DQSS), a simplified protocol for hierarchical dynamic quantum secret sharing (HDQSS) is proposed and it is shown that the protocol can be implemented using any existing protocol of quantum key distribution, quantum key agreement or secure direct quantum communication. The security of this proposed protocol against eavesdropping and collusion attacks is discussed with specific attention towards the issues related to the composability of the subprotocols that constitute the proposed protocol. The security and qubit efficiency of the proposed protocol is also compared with that of other existing protocols of DQSS. Further, it is shown that it is possible to design a semi-quantum protocol of HDQSS and in principle, the protocols of HDQSS can be implemented using any quantum state. It is also noted that the completely orthogonal-state-based realization of HDQSS protocol is possible and that HDQSS can be experimentally realized using a large number of alternative approaches.

Sandeep Mishra; Chitra Shukla; Anirban Pathak; R. Srikanth; Anu Venugopalan

2014-09-06T23:59:59.000Z

35

Quantum Graphical Models and Belief Propagation

Belief Propagation algorithms acting on Graphical Models of classical probability distributions, such as Markov Networks, Factor Graphs and Bayesian Networks, are amongst the most powerful known methods for deriving probabilistic inferences amongst large numbers of random variables. This paper presents a generalization of these concepts and methods to the quantum case, based on the idea that quantum theory can be thought of as a noncommutative, operator-valued, generalization of classical probability theory. Some novel characterizations of quantum conditional independence are derived, and definitions of Quantum n-Bifactor Networks, Markov Networks, Factor Graphs and Bayesian Networks are proposed. The structure of Quantum Markov Networks is investigated and some partial characterization results are obtained, along the lines of the Hammersley-Clifford theorem. A Quantum Belief Propagation algorithm is presented and is shown to converge on 1-Bifactor Networks and Markov Networks when the underlying graph is a tree. The use of Quantum Belief Propagation as a heuristic algorithm in cases where it is not known to converge is discussed. Applications to decoding quantum error correcting codes and to the simulation of many-body quantum systems are described.

Leifer, M.S. [Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, Waterloo Ont., N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo Ont., N2L 2Y5 (Canada)], E-mail: matt@mattleifer.info; Poulin, D. [Center for the Physics of Information, California Institute of Technology, 1200 E. California Boulevard, 107-81, Pasadena, CA 91125 (United States)], E-mail: dpoulin@ist.caltech.edu

2008-08-15T23:59:59.000Z

36

The NREL/Evident team will develop techniques to fabricate thin film solar cells where the absorption layers comprising the solar cells are derived from sintered semiconductor quantum dots.

Ginley, D. S.

2010-07-01T23:59:59.000Z

37

Computing prime factors with a Josephson phase qubit quantum processor

A quantum processor (QuP) can be used to exploit quantum mechanics to find the prime factors of composite numbers[1]. Compiled versions of Shor's algorithm have been demonstrated on ensemble quantum systems[2] and photonic systems[3-5], however this has yet to be shown using solid state quantum bits (qubits). Two advantages of superconducting qubit architectures are the use of conventional microfabrication techniques, which allow straightforward scaling to large numbers of qubits, and a toolkit of circuit elements that can be used to engineer a variety of qubit types and interactions[6, 7]. Using a number of recent qubit control and hardware advances [7-13], here we demonstrate a nine-quantum-element solid-state QuP and show three experiments to highlight its capabilities. We begin by characterizing the device with spectroscopy. Next, we produces coherent interactions between five qubits and verify bi- and tripartite entanglement via quantum state tomography (QST) [8, 12, 14, 15]. In the final experiment, we run a three-qubit compiled version of Shor's algorithm to factor the number 15, and successfully find the prime factors 48% of the time. Improvements in the superconducting qubit coherence times and more complex circuits should provide the resources necessary to factor larger composite numbers and run more intricate quantum algorithms.

Erik Lucero; Rami Barends; Yu Chen; Julian Kelly; Matteo Mariantoni; Anthony Megrant; Peter O'Malley; Daniel Sank; Amit Vainsencher; James Wenner; Ted White; Yi Yin; Andrew N. Cleland; John M. Martinis

2012-02-26T23:59:59.000Z

38

In 1990 Alcubierre, within the General Relativity model for space-time, proposed a scenario for `warp drive' faster than light travel, in which objects would achieve such speeds by actually being stationary within a bubble of space which itself was moving through space, the idea being that the speed of the bubble was not itself limited by the speed of light. However that scenario required exotic matter to stabilise the boundary of the bubble. Here that proposal is re-examined within the context of the new modelling of space in which space is a quantum system, viz a quantum foam, with on-going classicalisation. This model has lead to the resolution of a number of longstanding problems, including a dynamical explanation for the so-called `dark matter' effect. It has also given the first evidence of quantum gravity effects, as experimental data has shown that a new dimensionless constant characterising the self-interaction of space is the fine structure constant. The studies here begin the task of examining to what extent the new spatial self-interaction dynamics can play a role in stabilising the boundary without exotic matter, and whether the boundary stabilisation dynamics can be engineered; this would amount to quantum gravity engineering.

Reginald T. Cahill

2005-06-06T23:59:59.000Z

39

Eavesdropping without quantum memory

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

40

Self-field and magnetic-flux quantum mechanics

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

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

41

Deutsch's Universal Quantum Turing Machine (Revisited)

Deutsch, Feynman, and Manin viewed quantum computing as a kind of universal physical simulation procedure. Much of the writing about quantum Turing machines has shown how these machines can simulate an arbitrary unitary transformation on a finite number of qubits. This interesting problem has been addressed most famously in a paper by Deutsch, and later by Bernstein and Vazirani. Quantum Turing machines form a class closely related to deterministic and probabilistic Turing machines and one might hope to find a universal machine in this class. A universal machine is the basis of a notion of programmability. The extent to which universality has in fact been established by the pioneers in the field is examined and a key notion in theoretical computer science (universality) is scrutinised. In a forthcoming paper, the authors will also consider universality in the quantum gate model.

Willem Fouché; Johannes Heidema; Glyn Jones; Petrus H. Potgieter

2007-01-16T23:59:59.000Z

42

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to dominate flow tension forces. It is shown that the electromag- netic and surface tension forces domi- nate the flow by experimental measurements of segrega- tion in the weld pool. It is also shown that the surface tension driven

Eagar, Thomas W.

43

Preventing Quantum Hacking in Continuous Variable Quantum Key Distribution

Science Journals Connector (OSTI)

Security loopholes have been shown for discrete-variable Quantum Key Distribution (QKD). Here, we propose and provide experimental evidence of an attack targeting a continuous-variable...

Jouguet, Paul; Diamanti, Eleni; Kunz-Jacques, Sébastien

44

Quantum Bootstrapping via Compressed Quantum Hamiltonian Learning

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

45

Final Rulemaking, 10 CFR Part 1021, with Amendments Shown In Tracked Changes

Broader source: Energy.gov [DOE]

This document presents the final rule as issued September 27, 2011, amendments shown with changes tracked (additions in blue, deletions in red). Categorical exclusions are listed in Appendices A...

46

Science Journals Connector (OSTI)

A quantum R-matrix structure is presented for a family of exactly integrable multidimensional rational mappings related to lattice versions of the Korteweg–de Vries equation. It is shown that these mappings possess a commuting family of invariants.

F. W. Nijhoff; H. W. Capel; V. G. Papageorgiou

1992-08-15T23:59:59.000Z

47

DOE Takes Action to Stop the Sales of Air-Con Air Conditioner Models Shown

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

Takes Action to Stop the Sales of Air-Con Air Conditioner Takes Action to Stop the Sales of Air-Con Air Conditioner Models Shown to Violate Federal Energy Efficiency Appliance Standards DOE Takes Action to Stop the Sales of Air-Con Air Conditioner Models Shown to Violate Federal Energy Efficiency Appliance Standards September 23, 2010 - 12:00am Addthis Washington, DC - The Department of Energy announced today that it has taken action against Air-Con, International, requiring the company to stop selling certain air conditioning systems in the U.S. that have been shown to violate minimum energy efficiency appliance standards. DOE is proposing a civil penalty of more than $230,000 for importing and distributing these inefficient cooling products. This action and the proposed penalties are part of the Department's continued commitment to act aggressively to remove

48

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

49

Generation and Control of Chains of Entangled Atom-Ion Pairs with Quantum Light

Coherent control using quantum light incident upon molecules in an optical lattice is shown to give rise to a direct way of writing arbitrary sequences of entangled atom-ion pairs. There is no evident limitation on the length of the word (i.e., the number of qbits) that can be formed.

Shapiro, Moshe [Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z3 (Canada); Department of Chemical Physics, Weizmann Institute, Rehovot 76100 (Israel); Brumer, Paul [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)

2011-04-15T23:59:59.000Z

50

cord Â· 10% fabric 4 #12;Thermal ConductivityThermal Conductivity Â· Low thermal conductivity of 0.242W conventional aggregatesconventional aggregates 5 #12;Thermal ConductivityThermal Conductivity Â·Â·Shredded tireCE990 Graduate Seminar Presentations DISCLAIMER The presentation materials shown in this file were

Saskatchewan, University of

51

Several studies have shown that the availability of solar power plants often is

the utility, solar and research industries. Effective Capacity Metrics Simple metrics can be estimatedSeveral studies have shown that the availability of solar power plants often is high during times conditioning. These peaks are intensi- fied during heat waves, which are fueled by solar gain. Thus

Perez, Richard R.

52

1. INTRODUCTION Polycrystalline CdTe thin films solar cells have shown long

to the solar panel that can be adapted to any kind of shape and is easy to deploy in space. We have developed1. INTRODUCTION Polycrystalline CdTe thin films solar cells have shown long term stable performance for the solar cell, therefore high specific power (ratio of out- put power to the weight) solar cells

Romeo, Alessandro

53

A Majorana-Oppenheimer formulation of quantum electrodynamics

Science Journals Connector (OSTI)

It is shown that, according to suggestions by Majorana and Oppenheimer, it is possible to formulate quantum electrodynamics...

E. Giannetto

1985-01-01T23:59:59.000Z

54

All inorganic colloidal quantum dot LEDs

This thesis presents the first colloidal quantum dot light emitting devices (QD-LEDs) with metal oxide charge transport layers. Colloidally synthesized quantum dots (QDs) have shown promise as the active material in ...

Wood, Vanessa Claire

2007-01-01T23:59:59.000Z

55

The Quantum Field as a Quantum Computer

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

56

Quantum Terahertz Electrodynamics and Macroscopic Quantum Tunneling in Layered Superconductors

of macroscopic quantum tunneling (MQT) in stacks of intrinsic Josephson junctions. Because of the long numbers: 74.72.Hs, 74.78.Fk The recent surge of interest in stacks of intrinsic Josephson junctions of stacks of Josephson junctions in quantum electronics [6]. This requires a quantum theory capable

Nori, Franco

57

Relation of the Total Nitrogen of the Soil to its Needs as Shown in Pot Experiments.

Sanders s ilt ____________ C orn 30.0 29.28.0 1.39 .4170 19081908 SsC orn 8.2G rass 4.6 9.9 1908 D1929 Yazoo clay _____________ C orn 15.3 32.9 1909 DD2822 Sherm an lo am _________ M usta rd 1.5 2.4 19091910 DC orn 37.5 41.0 D A verage _ __________ 14...TEXAS AGRICULTURAL EXPERIMENT STATIONS 564-812-5m BULLETIN NO. 151 AUGUST I912 Relation of the Total Nitrogen of the Soil to its Needs as Shown in Pot Experiments ofG. S. P'RAPS, Chemist. Shwnh????? COLLEGE STATION, BRAZOS C O U N T Y...

Fraps, G. S.

1912-01-01T23:59:59.000Z

58

Quantum simulation I. M. Georgescu

, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar, Saitama, 351-0198, Japan and Qatar Environment and Energy Research Institute, Doha, Qatar Franco Nori CEMS, high-energy physics, atomic physics, quantum chemistry, and cosmology. Quantum simulation could

Nori, Franco

59

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

193 UNIT NUMBER: 197 UNIT NAME: CONCRETE RUBBLE PILE (30) REGULATORY STATUS: AOC LOCATION: Outside plant security fence, north of the plant on Big Bayou Creek on private property....

60

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

7 UNIT NUMBER UNIT NAME Rubble oile 41 REGULATORY STATUS: AOC LOCATION: Butler Lake Dam, West end of Butler Lake top 20 ft wide, 10 ft APPROXIMATE DIMENSIONS: 200 ft long, base 30...

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61

Smooth horizons and quantum ripples

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

62

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

63

Fault-tolerant quantum computer architectures using hierarchies of quantum error-correcting codes

Quantum computers have been shown to efficiently solve a class of problems for which no efficient solution is otherwise known. Physical systems can implement quantum computation, but devising realistic schemes is an extremely ...

Cross, Andrew W. (Andrew William), 1979-

2008-01-01T23:59:59.000Z

64

Quantum dot device tunable from single to triple dot system

We present a lateral quantum dot device which has a tunable number of quantum dots. Depending on easily tunable gate voltages, one, two or three quantum dots are found. They are investigated in transport and charge detection.

Rogge, M. C.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover (Germany); Pierz, K. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

2013-12-04T23:59:59.000Z

65

QKD Quantum Channel Authentication

Several simple yet secure protocols to authenticate the quantum channel of various QKD schemes, by coupling the photon sender's knowledge of a shared secret and the QBER Bob observes, are presented. It is shown that Alice can encrypt certain portions of the information needed for the QKD protocols, using a sequence whose security is based on computational-complexity, without compromising all of the sequence's entropy. It is then shown that after a Man-in-the-Middle attack on the quantum and classical channels, there is still enough entropy left in the sequence for Bob to detect the presence of Eve by monitoring the QBER. Finally, it is shown that the principles presented can be implemented to authenticate the quantum channel associated with any type of QKD scheme, and they can also be used for Alice to authenticate Bob.

J. T. Kosloski

2006-04-02T23:59:59.000Z

66

Stabilizing quantum information

Science Journals Connector (OSTI)

The dynamical-algebraic structure underlying all the schemes for quantum information stabilization is argued to be fully contained in the reducibility of the operator algebra describing the interaction with the environment of the coding quantum system. This property amounts to the existence of a nontrivial group of symmetries for the global dynamics. We provide a unified framework that allows us to build systematically additional classes of error correcting codes and noiseless subsystems. It is shown that by using symmetrization strategies one can artificially produce noiseless subsystems supporting universal quantum computation.

Paolo Zanardi

2000-12-05T23:59:59.000Z

67

Nonadiabatic quantum state engineering driven by fast quench dynamics

There are a number of tasks in quantum information science that exploit non-transitional adiabatic dynamics. Such a dynamics is bounded by the adiabatic theorem, which naturally imposes a speed limit in the evolution of quantum systems. Here, we investigate an approach for quantum state engineering exploiting a shortcut to the adiabatic evolution, which is based on rapid quenches in a continuous-time Hamiltonian evolution. In particular, this procedure is able to provide state preparation faster than the adiabatic brachistochrone. Remarkably, the evolution time in this approach is shown to be ultimately limited by its "thermodynamical cost,"provided in terms of the average work rate (average power) of the quench process. We illustrate this result in a scenario that can be experimentally implemented in a nuclear magnetic resonance setup.

Marcela Herrera; Marcelo S. Sarandy; Eduardo I. Duzzioni; Roberto M. Serra

2014-03-03T23:59:59.000Z

68

Electric Time in Quantum Cosmology

Effective quantum cosmology is formulated with a realistic global internal time given by the electric vector potential. New possibilities for the quantum behavior of space-time are found, and the high-density regime is shown to be very sensitive to the specific form of state realized.

Stephon Alexander; Martin Bojowald; Antonino Marciano; David Simpson

2012-12-10T23:59:59.000Z

69

To Principles of Quantum Mechanics Development

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

70

Quantum correlation via quantum coherence

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

71

Classical and Quantum Polyhedra

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

72

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

Name of Petitioner: Name of Petitioner: Date of Filing: Case Number: Department of Energy Washington, DC 20585 JUL 2 2 2009 DEPARTMENT OF ENERGY OFFICE OF HEARINGS AND APPEALS Appeal Dean P. Dennis March 2, 2009 TBA-0072 Dean D. Dennis filed a complaint of retaliation under the Department of Energy (DOE) Contractor Employee Protection Program, 10 C.F.R. Part 708. Mr. Dennis alleged that he engaged in protected activity and that his employer, National Security Technologies, LLC (NSTec ), subsequently terminated him. An Office of Hearings and Appeals (OHA) Hearing Officer denied relief in Dean P. Dennis, Case No. TBH-0072, 1 and Mr. Dennis filed the instant appeal. As discussed below, the appeal is denied. I. Background The DOE established its Contractor Employee Protection Program to "safeguard public

73

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

. . . . . . . . . .: LEAVE BLANK (NARA use only) JOB NUMBER N/-&*W- 9d - 3 DATE RECEIVED " -1s - 9 J - NOTIFICATION TOAGENCY , In accordance with the provisions of 44 U.S.C. 3303a the disposition request. including amendments, is ap roved except , . l for items that may be marke,, ,"dis osition not approved" or "withdrawn in c o i m n 10. 4. NAME OF PERSON WITH WHOM TO CONFER 5 TELEPHONE Jannie Kindred (202) 5&-333 5 - 2 -96 6 AGENCYCERTIFICATION -. ~ - I hereby certify that I am authorized to act for this agency in matters pertaining to the disposition of its records and that the records roposed for disposal are not now needed for the business of this agency or wiRnot be needed after t G t r & s s d ; and that written concurrence from

74

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

Supports CMM-SW Level 3 Supports CMM-SW Level 3 Mapping of the DOE Information Systems Engineering Methodology to the Software Engineering Institute (SEI) Software Capability Maturity Model (CMM-SW) level 3. Date: September 2002 Page 1 KPA Number KPA Activity SEM Section SEM Work Product SQSE Web site http://cio.doe.gov/sqse ORGANIZATION PROCESS FOCUS OPF-1 The software process is assessed periodically, and action plans are developed to address the assessment findings. Chapter 1 * Organizational Process Management * Process Improvement Action Plan * Methodologies ! DOE Methodologies ! SEM OPF-2 The organization develops and maintains a plan for its software process development and improvement activities. Chapter 1 * Organizational Process Management * Process Improvement

75

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

76

Purification of noisy quantum measurements

We consider the problem of improving noisy quantum measurements by suitable preprocessing strategies making many noisy detectors equivalent to a single ideal detector. For observables pertaining to finite-dimensional systems (e.g., qubits or spins) we consider preprocessing strategies that are reminiscent of quantum error correction procedures and allow one to perfectly measure an observable on a single quantum system for increasing number of inefficient detectors. For measurements of observables with an unbounded spectrum (e.g., photon number and homodyne and heterodyne detection), the purification of noisy quantum measurements can be achieved by preamplification as suggested by Yuen [Opt. Lett. 12, 789 (1987)].

Dall'Arno, Michele; D'Ariano, Giacomo Mauro [Quit Group, Dipartimento di Fisica 'A. Volta', via Bassi 6, I-27100 Pavia (Italy); Istituto Nazionale di Fisica Nucleare, Gruppo IV, via Bassi 6, I-27100 Pavia (Italy); Sacchi, Massimiliano F. [Quit Group, Dipartimento di Fisica 'A. Volta', via Bassi 6, I-27100 Pavia (Italy); Istituto di Fotonica e Nanotecnologie (IFN-CNR), Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

2010-10-15T23:59:59.000Z

77

Modulational instability of electromagnetic waves in a collisional quantum magnetoplasma

The modulational instability of right-hand circularly polarized electromagnetic electron cyclotron (CPEM-EC) wave in a magnetized quantum plasma is studied taking into account the collisional effects. Employing quantum hydrodynamic and nonlinear Schrödinger equations, the dispersion relation of modulated CPEM-EC wave in a collisional plasma has been derived. It is found that this wave is unstable in such a plasma system and the growth rate of the associated instability depends on various parameters such as electron Fermi temperature, plasma number density, collision frequency, and modulation wavenumber. It is shown that while the increase of collision frequency leads to increase of the growth rate of instability, especially at large wavenumber limit, the increase of plasma number density results in more stable modulated CPEM-EC wave. It is also found that in contrast to collisionless plasma in which modulational instability is restricted to small wavenumbers, in collisional plasma, the interval of instability occurrence can be extended to a large domain.

Niknam, A. R., E-mail: a-niknam@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of); Rastbood, E.; Bafandeh, F.; Khorashadizadeh, S. M., E-mail: smkhorashadi@birjand.ac.ir [Physics Department of Birjand University, Birjand (Iran, Islamic Republic of)

2014-04-15T23:59:59.000Z

78

We present here a quantum tripwire, which is a quantum optical interrogation technique capable of detecting an intrusion with very low probability of the tripwire being revealed to the intruder. Our scheme combines interaction-free measurement with the quantum Zeno effect in order to interrogate the presence of the intruder without interaction. The tripwire exploits a curious nonlinear behaviour of the quantum Zeno effect we discovered, which occurs in a lossy system. We also employ a statistical hypothesis testing protocol, allowing us to calculate a confidence level of interaction-free measurement after a given number of trials. As a result, our quantum intruder alert system is robust against photon loss and dephasing under realistic atmospheric conditions and its design minimizes the probabilities of false positives and false negatives as well as the probability of becoming visible to the intruder.

Petr M. Anisimov; Daniel J. Lum; S. Blane McCracken; Hwang Lee; Jonathan P. Dowling

2010-02-17T23:59:59.000Z

79

Quantum correlation cost of the weak measurement

Quantum correlation cost (QCC) characterizing how much quantum correlation is used in a weak-measurement process is presented based on the trace norm. It is shown that the QCC is related to the trace-norm-based quantum discord (TQD) by only a factor that is determined by the strength of the weak measurement, so it only catches partial quantumness of a quantum system compared with the TQD. We also find that the residual quantumness can be `extracted' not only by the further von Neumann measurement, but also by a sequence of infinitesimal weak measurements. As an example, we demonstrate our outcomes by the Bell-diagonal state.

Jun Zhang; Shao-xiong Wu; Chang-shui Yu

2014-09-14T23:59:59.000Z

80

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

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

81

We present a general model for quantum channels with memory, and show that it is sufficiently general to encompass all causal automata: any quantum process in which outputs up to some time t do not depend on inputs at times t' > t can be decomposed into a concatenated memory channel. We then examine and present different physical setups in which channels with memory may be operated for the transfer of (private) classical and quantum information. These include setups in which either the receiver or a malicious third party have control of the initializing memory. We introduce classical and quantum channel capacities for these settings, and give several examples to show that they may or may not coincide. Entropic upper bounds on the various channel capacities are given. For forgetful quantum channels, in which the effect of the initializing memory dies out as time increases, coding theorems are presented to show that these bounds may be saturated. Forgetful quantum channels are shown to be open and dense in the set of quantum memory channels.

Dennis Kretschmann; Reinhard F. Werner

2005-02-17T23:59:59.000Z

82

Quantum–enhanced information processing

Science Journals Connector (OSTI)

...conventional (classical) computing device. We will show how quantum...life. Anyone who has enjoyed listening to music on a CD, watching...quantum computer is any physical device that exploits the greatly enhanced...on any conceivable computing device. Multi- plying numbers or...

2000-01-01T23:59:59.000Z

83

Damped quantum harmonic oscillator

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

84

Rotation of Adsorbed H2 K. Svensson, L. Bengtsson, J. Bellman, M. Hassel, M. Persson, and S. Andersson, Sweden (Received 10 March 1999) We report experimental and theoretical evidence of H2 adsorbed in a confined quantum rotor state on a stepped copper surface. Rotational transitions of step-adsorbed para-H2

Persson, Mats

85

-Dimensional Localization of Quantum Vortices in Disordered Josephson Junction Arrays Alexander van Oudenaarden, S. J. K-dimensional arrays of Josephson junctions was studied experimentally. The vortices localize in disordered arrays of Josephson junctions. The great advantage of these systems is that disorder can be introduced in a very

van Oudenaarden, Alexander

86

the Progressive Decoherence of the "Meter" in a Quantum Measurement M. Brune, E. Hagley, J. Dreyer, X. Mai^tre, A. The mesoscopic superposition was the equivalent of an "atom 1 measuring apparatus" system in which the "meter a macroscopic apparatus ("meter") and a microscopic system ("atom") results in their entangle- ment and produces

Wunderlich, Christof

87

Transport and Quantum Phase Transitions in Coupled Josephson-Junction Chains with Charge Frustration Mahn of ultrasmall Josephson junctions, where the particle-hole symmetry is broken by the gate voltage applied blockade. Especially, in Josephson-junction arrays, the charging energy in competition with the Josephson

Choi, Mahn-Soo

88

VOLUME 87, NUMBER 23 P H Y S I C A L R E V I E W L E T T E R S 3 DECEMBER 2001 Optimal Quantum Pumps

Pumps J. E. Avron,1 A. Elgart,2 G. M. Graf,3 and L. Sadun4 1 Department of Physics, Technion, 32000, Austin, Texas 78712 (Received 8 May 2001; published 13 November 2001) We study adiabatic quantum pumps on time scales that are short relative to the cycle of the pump. In this regime the pump is characterized

Avron, Joseph

89

Quantum thermodynamic cooling cycle

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

90

Quantum thermodynamic cooling cycle

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

91

To Principles of Quantum Mechanics Development

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

92

Free motion in deformed (quantum) four-dimensional space

It is shown that trajectories of free motion of the particles in deformed ("quantum") four dimensional space-time are quadratic curves.

A. N. Leznov

2007-07-23T23:59:59.000Z

93

Quantum statistical calculation of cluster abundances in hot dense matter

The cluster abundances are calculated from a quantum statistical approach taking into account in-medium corrections. For arbitrary cluster size the self-energy and Pauli blocking shifts are considered. Exploratory calculations are performed for symmetric matter at temperature $T=5$ MeV and baryon density $\\varrho=0.0156$ fm$^{-3}$ to be compared with the solar element distribution. It is shown that the abundances of weakly bound nuclei with mass number $4

Gerd Ropke

2014-07-01T23:59:59.000Z

94

The Unreasonable Success of Quantum Probability II: Quantum Measurements as Universal Measurements

In the first part of this two-part article, we have introduced and analyzed a multidimensional model, called the 'general tension-reduction' (GTR) model, able to describe general quantum-like measurements with an arbitrary number of outcomes, and we have used it as a general theoretical framework to study the most general possible condition of lack of knowledge in a measurement, so defining what we have called a 'universal measurement'. In this second part, we present the formal proof that universal measurements, which are averages over all possible forms of fluctuations, produce the same probabilities as measurements characterized by 'uniform' fluctuations on the measurement situation. Since quantum probabilities can be shown to arise from the presence of such uniform fluctuations, we have proven that they can be interpreted as the probabilities of a first-order non-classical theory, describing situations in which the experimenter lacks complete knowledge about the nature of the interaction between the measuring apparatus and the entity under investigation. This same explanation can be applied -- mutatis mutandis -- to the case of cognitive measurements, made by human subjects on conceptual entities, or in decision processes, although it is not necessarily the case that the structure of the set of states would be in this case strictly Hilbertian. We also show that universal measurements correspond to maximally 'robust' descriptions of indeterministic reproducible experiments, and since quantum measurements can also be shown to be maximally robust, this adds plausibility to their interpretation as universal measurements, and provides a further element of explanation for the great success of the quantum statistics in the description of a large class of phenomena.

Diederik Aerts; Massimiliano Sassoli de Bianchi

2014-01-12T23:59:59.000Z

95

Page 1 MAES Project Review Procedures The projects shown on the Project Review list (distributed to the Peer Review Committee o Comply with MAES Project Review Procedures o After the seminar and Project Review and ensure overall compliance with established procedures for MAES Project Reviews Internal

Maxwell, Bruce D.

96

6/5/2014 Physics Tutoring List Names shown are either graduate students or Physics majors charging fees for their tutoring services. These persons are not sponsored by UCLA or the Physics & Astronomy Department. Tutor Name Phone E-mail Subject(s) Bauer, David 419.460.1267 dbauer88@gmail.com Physics

Durian, Douglas

97

A close-up of the Sun (shown in ultraviolet light) reveals a mottled surface, bright flares,

#12;#12;A close-up of the Sun (shown in ultraviolet light) reveals a mottled surface, bright flares, and tongues of hot gas leaping into space. Though they look like burns in the face of the Sun, sunspots circle in the center of the photo--allows scientists to see the solar wind streaming away from the Sun

Christian, Eric

98

Quantum information with Rydberg atoms

Science Journals Connector (OSTI)

Rydberg atoms with principal quantum number n?1 have exaggerated atomic properties including dipole-dipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom qubits. The availability of a strong long-range interaction that can be coherently turned on and off is an enabling resource for a wide range of quantum information tasks stretching far beyond the original gate proposal. Rydberg enabled capabilities include long-range two-qubit gates, collective encoding of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing.

M. Saffman; T. G. Walker; K. Mølmer

2010-08-18T23:59:59.000Z

99

Transport and Dissipation in Quantum Pumps

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

100

Quantum interference within the complex quantum Hamilton-Jacobi formalism

Quantum interference is investigated within the complex quantum Hamilton-Jacobi formalism. As shown in a previous work [Phys. Rev. Lett. 102 (2009) 250401], complex quantum trajectories display helical wrapping around stagnation tubes and hyperbolic deflection near vortical tubes, these structures being prominent features of quantum caves in space-time Argand plots. Here, we further analyze the divergence and vorticity of the quantum momentum function along streamlines near poles, showing the intricacy of the complex dynamics. Nevertheless, despite this behavior, we show that the appearance of the well-known interference features (on the real axis) can be easily understood in terms of the rotation of the nodal line in the complex plane. This offers a unified description of interference as well as an elegant and practical method to compute the lifetime for interference features, defined in terms of the average wrapping time, i.e., considering such features as a resonant process.

Chou, Chia-Chun, E-mail: chiachun@mail.utexas.ed [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Sanz, Angel S., E-mail: asanz@imaff.cfmac.csic.e [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, Salvador, E-mail: s.miret@imaff.cfmac.csic.e [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Wyatt, Robert E., E-mail: wyattre@mail.utexas.ed [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712 (United States)

2010-10-15T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

101

Renormalization of Quantum Anosov Maps: Reduction to Fixed Boundary Conditions

A renormalization scheme is introduced to study quantum Anosov maps (QAMs) on a torus for general boundary conditions (BCs), whose number ($k$) is always finite. It is shown that the quasienergy eigenvalue problem of a QAM for {\\em all} $k$ BCs is exactly equivalent to that of the renormalized QAM (with Planck's constant $\\hbar ^{\\prime}=\\hbar /k$) at some {\\em fixed} BCs that can be of four types. The quantum cat maps are, up to time reversal, fixed points of the renormalization transformation. Several results at fixed BCs, in particular the existence of a complete basis of ``crystalline'' eigenstates in a classical limit, can then be derived and understood in a simple and transparent way in the general-BCs framework.

Itzhack Dana

2000-05-18T23:59:59.000Z

102

Longitudinal dielectric permettivity of quantum Maxwell collisional plasmas

The kinetic equation of Wigner -- Vlasov -- Boltzmann with collision integral in relaxation BGK (Bhatnagar, Gross and Krook) form in coordinate space for quantum non--degenerate (Maxwellian) collisional plasma is used. Exact expression (within the limits of considered model) is found. The analysis of longitudinal dielectric permeability is done. It is shown that in the limit when Planck's constant tends to zero of expression for dielectric permettivity transforms into the classical case of dielectric permettivity. At small values of wave number it has been received the solution of the dispersion equation. Damping of plasma oscillations has been analized. The analytical comparison with the dielectric Mermin' function received with the use of the kinetic equation in momentum space is done. Graphic comparison of the real and imaginary parts of dielectric permettivity of quantum and classical plasma is done also.

A. V. Latyshev; A. A. Yushkanov

2010-03-12T23:59:59.000Z

103

Improving Quantum Algorithms for Quantum Chemistry

We present several improvements to the standard Trotter-Suzuki based algorithms used in the simulation of quantum chemistry on a quantum computer. First, we modify how Jordan-Wigner transformations are implemented to reduce their cost from linear or logarithmic in the number of orbitals to a constant. Our modification does not require additional ancilla qubits. Then, we demonstrate how many operations can be parallelized, leading to a further linear decrease in the parallel depth of the circuit, at the cost of a small constant factor increase in number of qubits required. Thirdly, we modify the term order in the Trotter-Suzuki decomposition, significantly reducing the error at given Trotter-Suzuki timestep. A final improvement modifies the Hamiltonian to reduce errors introduced by the non-zero Trotter-Suzuki timestep. All of these techniques are validated using numerical simulation and detailed gate counts are given for realistic molecules.

M. B. Hastings; D. Wecker; B. Bauer; M. Troyer

2014-03-23T23:59:59.000Z

104

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

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

105

A Description of Quantum Chaos

A measure describing the chaos of a dynamics was introduced by two complexities in information dynamics, and it is called the chaos degree. In particular, the entropic chaos degree has been used to characterized several dynamical maps such that logistis, Baker's, Tinckerbel's in classical or quantum systems. In this paper, we give a new treatment of quantum chaos by defining the entropic chaos degree for quantum transition dynamics, and we prove that every non-chaotic quantum dynamics, e.g., dissipative dynamics, has zero chaos degree. A quantum spin 1/2 system is studied by our chaos degree, and it is shown that this degree well describes the chaotic behavior of the spin system.

Kei Inoue; Andrzej Kossakowski; Masanori Ohya

2004-06-30T23:59:59.000Z

106

Quantum Theory and Spacelike Measurements

Experimentally observed violations of Bell inequalities rule out local realistic theories. Consequently, the quantum state vector becomes a strong candidate for providing an objective picture of reality. However, such an ontological view of quantum theory faces difficulties when spacelike measurements on entangled states have to be described, because time ordering of spacelike events can change under Lorentz-Poincar\\'e transformations. In the present paper it is shown that a necessary condition for consistency is to require state vector reduction on the backward light-cone. A fresh approach to the quantum measurement problem appears feasible within such a framework.

Bernd A. Berg

1998-01-04T23:59:59.000Z

107

Simulations of Quantum Turing Machines by Quantum Multi-Stack Machines

As was well known, in classical computation, Turing machines, circuits, multi-stack machines, and multi-counter machines are equivalent, that is, they can simulate each other in polynomial time. In quantum computation, Yao [11] first proved that for any quantum Turing machines $M$, there exists quantum Boolean circuit $(n,t)$-simulating $M$, where $n$ denotes the length of input strings, and $t$ is the number of move steps before machine stopping. However, the simulations of quantum Turing machines by quantum multi-stack machines and quantum multi-counter machines have not been considered, and quantum multi-stack machines have not been established, either. Though quantum counter machines were dealt with by Kravtsev [6] and Yamasaki {\\it et al.} [10], in which the machines count with $0,\\pm 1$ only, we sense that it is difficult to simulate quantum Turing machines in terms of this fashion of quantum computing devices, and we therefore prove that the quantum multi-counter machines allowed to count with $0,\\pm 1,\\pm 2,...,\\pm n$ for some $n>1$ can efficiently simulate quantum Turing machines. Therefore, our mail goals are to establish quantum multi-stack machines and quantum multi-counter machines with counts $0,\\pm 1,\\pm 2,...,\\pm n$ and $n>1$, and particularly to simulate quantum Turing machines by these quantum computing devices.

Daowen Qiu

2005-06-06T23:59:59.000Z

108

Hierarchical quantum Ising model

Science Journals Connector (OSTI)

A quantum Ising chain with both the exchange couplings and the transverse fields arranged in a hierarchical way is considered. Exact analytical results for the critical line and dispersion relation of the low-energy excitations are obtained. It is shown that only when R1=R2>Rc, where R1 and R2 are the hierarchical parameters for the exchange couplings and the transverse fields, respectively, does the system preserve a logarithmic singularity in the specific heat.

Zhifang Lin and Ruibao Tao

1990-06-01T23:59:59.000Z

109

Entanglement Cost of Quantum Channels

The entanglement cost of a quantum channel is the minimal rate at which entanglement (between sender and receiver) is needed in order to simulate many copies of a quantum channel in the presence of free classical communication. In this paper we show how to express this quantity as a regularized optimization of the entanglement formation over states that can be generated between sender and receiver. Our formula is the channel analog of a well-known formula for the entanglement cost of quantum states in terms of the entanglement of formation; and shares a similar relation to the recently shattered hope for additivity. The entanglement cost of a quantum channel can be seen as the analog of the quantum reverse Shannon theorem in the case where free classical communication is allowed. The techniques used in the proof of our result are then also inspired by a recent proof of the quantum reverse Shannon theorem and feature the one-shot formalism for quantum information theory, the post-selection technique for quantum channels as well as von Neumann's minimax theorem. We discuss two applications of our result. First, we are able to link the security in the noisy-storage model to a problem of sending quantum rather than classical information through the adversary's storage device. This not only improves the range of parameters where security can be shown, but also allows us to prove security for storage devices for which no results were known before. Second, our result has consequences for the study of the strong converse quantum capacity. Here, we show that any coding scheme that sends quantum information through a quantum channel at a rate larger than the entanglement cost of the channel has an exponentially small fidelity.

Mario Berta; Fernando Brandao; Matthias Christandl; Stephanie Wehner

2011-08-26T23:59:59.000Z

110

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

111

Quantum Computers, Factoring, and Decoherence

In a quantum computer any superposition of inputs evolves unitarily into the corresponding superposition of outputs. It has been recently demonstrated that such computers can dramatically speed up the task of finding factors of large numbers -- a problem of great practical significance because of its cryptographic applications. Instead of the nearly exponential ($\\sim \\exp L^{1/3}$, for a number with $L$ digits) time required by the fastest classical algorithm, the quantum algorithm gives factors in a time polynomial in $L$ ($\\sim L^2$). This enormous speed-up is possible in principle because quantum computation can simultaneously follow all of the paths corresponding to the distinct classical inputs, obtaining the solution as a result of coherent quantum interference between the alternatives. Hence, a quantum computer is sophisticated interference device, and it is essential for its quantum state to remain coherent in the course of the operation. In this report we investigate the effect of decoherence on the quantum factorization algorithm and establish an upper bound on a ``quantum factorizable'' $L$ based on the decoherence suffered per operational step.

I. Chuang; Raymond Laflamme; P. Shor; W. Zurek

1995-03-08T23:59:59.000Z

112

Microwave Quantum Illumination

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or 'quantum radar', is shown to be superior to that of any classical microwave radar of equal transmitted energy.

Shabir Barzanjeh; Saikat Guha; Christian Weedbrook; David Vitali; Jeffrey H. Shapiro; Stefano Pirandola

2014-10-15T23:59:59.000Z

113

Microwave Quantum Illumination

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or 'quantum radar', is shown to be superior to that of any classical microwave radar of equal transmit...

Barzanjeh, Shabir; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

2014-01-01T23:59:59.000Z

114

EPR's reality criterion and quantum realism

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

115

Large-amplitude solitons in gravitationally balanced quantum plasmas

Using the quantum fluid model for self-gravitating quantum plasmas with the Bernoulli pseudopotential method and taking into account the relativistic degeneracy effect, it is shown that gravity-induced large-amplitude density rarefaction solitons can exist in gravitationally balanced quantum plasmas. These nonlinear solitons are generated due to the force imbalance between the gravity and the quantum fluid pressure via local density perturbations, similar to that on shallow waters. It is found that both the fluid mass-density and the atomic-number of the constituent ions have significant effect on the amplitude and width of these solitonic profiles. Existence of a large-scale gravity-induced solitonic activities on neutron-star surface, for instance, can be a possible explanation for the recently proposed resonant shattering mechanism [D. Tsang et al., Phys. Rev. Lett. 108, 011102 (2012)] causing the intense short gamma ray burst phenomenon, in which release of ?10{sup 46}–10{sup 47} ergs would be possible from the surface. The resonant shattering of the crust in a neutron star has been previously attributed to the crust-core interface mode and the tidal surface tensions. We believe that current model can be a more natural explanation for the energy liberation by solitonic activities on the neutron star surfaces, without a requirement for external mergers like other neutron stars or black holes for the crustal shatter.

Akbari-Moghanjoughi, M. [Department of Physics, Faculty of Sciences, Azarbaijan Shahid Madani University, 51745-406 Tabriz (Iran, Islamic Republic of); International Centre for Advanced Studies in Physical Sciences and Institute for Theoretical Physics, Ruhr University Bochum, D-44780 Bochum (Germany)

2014-08-15T23:59:59.000Z

116

Orbits of hybrid systems as qualitative indicators of quantum dynamics

Hamiltonian theory of hybrid quantum-classical systems is used to study dynamics of the classical subsystem coupled to different types of quantum systems. It is shown that the qualitative properties of orbits of the classical subsystem clearly indicate if the quantum subsystem does or does not have additional conserved observables.

N. Buric; D. B. Popovic; M. Radonjic; S. Prvanovic

2014-03-03T23:59:59.000Z

117

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

118

Planck's quantum-driven integer quantum Hall effect in chaos

The integer quantum Hall effect (IQHE) and chaos are commonly conceived as being unrelated. Contrary to common wisdoms, we find in a canonical chaotic system, the kicked spin-$1/2$ rotor, a Planck's quantum($h_e$)-driven phenomenon bearing a firm analogy to IQHE but of chaos origin. Specifically, the rotor's energy growth is unbounded ('metallic' phase) for a discrete set of critical $h_e$-values, but otherwise bounded ('insulating' phase). The latter phase is topological in nature and characterized by a quantum number ('quantized Hall conductance'). The number jumps by unity whenever $h_e$ decreases passing through each critical value. Our findings, within the reach of cold-atom experiments, indicate that rich topological quantum phenomena may emerge from chaos.

Yu Chen; Chushun Tian

2014-09-18T23:59:59.000Z

119

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

120

Quantum theory from one global symmetry

It is shown that unitary quantum theory is not only consistent with but follows from decompositional equivalence: the principle that there is no preferred decomposition of the universe into systems, or alternatively, that there is no preferred quantum reference frame. Decompositional equivalence requires unitary quantum theory to be both observer- and scale-independent, requires time, "systems" and all classical information to be strictly observer-relative, and imposes an unavoidable free-energy cost on the acquisition of observational outcomes. This free energy cost of observation is characterized from first principles and shown to accord with known costs of information acquisition and storage by human observers.

Chris Fields

2014-06-17T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

121

Quantum walks and quantum search on graphene lattices

Quantum walks have been very successful in the development of search algorithms in quantum information, in particular in the development of spatial search algorithms. However, the construction of continuous-time quantum search algorithms in two-dimensional lattices has proved difficult, requiring additional degrees of freedom. Here, we demonstrate that continuous-time quantum walk search is possible in two-dimensions by changing the search topology to a graphene lattice, utilising the Dirac point in the energy spectrum. This is made possible by making a change to standard methods of marking a particular site in the lattice. Various ways of marking a site are shown to result in successful search protocols. We further establish that the search can be adapted to transfer probability amplitude across the lattice between specific lattice sites thus establishing a line of communication between these sites.

Iain Foulger; Sven Gnutzmann; Gregor Tanner

2015-01-29T23:59:59.000Z

122

Synthesis of Ternary Quantum Logic Circuits by Decomposition

Recent research in multi-valued logic for quantum computing has shown practical advantages for scaling up a quantum computer. Multivalued quantum systems have also been used in the framework of quantum cryptography, and the concept of a qudit cluster state has been proposed by generalizing the qubit cluster state. An evolutionary algorithm based synthesizer for ternary quantum circuits has recently been presented, as well as a synthesis method based on matrix factorization.In this paper, a recursive synthesis method for ternary quantum circuits based on the Cosine-Sine unitary matrix decomposition is presented.

Faisal Shah Khan; Marek Perkowski

2005-11-04T23:59:59.000Z

123

Quantum potential energy as concealed motion

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

124

BETTI NUMBERS OF HYPERSURFACE COMPLEMENTS LAURENTIU MAXIM

L2 ÂBETTI NUMBERS OF HYPERSURFACE COMPLEMENTS LAURENTIU MAXIM Abstract. In [DJL07] it was shown that if A is an affine hyperplane arrange- ment in Cn, then at most one of the L2ÂBetti numbers b (2) i (Cn \\ A, id of [FLM09, LM06] about L2ÂBetti numbers of plane curve complements. 1. Introduction Let M be any

Maxim, Laurentiu-George

125

Randomization theorems for quantum channels

The classical randomization criterion is an important result of statistical decision theory. Recently, a quantum analogue has been proposed, giving equivalent conditions for two sets of quantum states, ensuring existence of a quantum channel mapping one set close to the other, in $L_1$-distance. In the present paper, we extend these concepts in several ways. First, sets of states are replaced by channels and randomization is performed by either post- or pre-composition with another channel. The $L_1$-distance is replaced by the diamond norm. Secondly, the maps are not required to be completely positive, but positivity is given by an admissible family of convex cones. It is shown that the randomization theorems, generalizing both quantum and classical randomization criteria, can be proved in the framework of base section norms, including the diamond norm and its dual. The theory of such norms is developed in the Appendix.

Anna Jencova

2014-04-15T23:59:59.000Z

126

InAs/GaAs Quantum-Dot Intermediate-Band Solar Cells

Science Journals Connector (OSTI)

Results for quantum-dot intermediate-band solar cells are presented. It is shown that quantum dots in conventional p-i-n structures can extend the photoresponse to 1300 nm, well...

Grenko, Alysha; Kimukin, Ibrahim; Walker, John; Towe, Elias

127

Amplification, Redundancy, and the Quantum Chernoff Information

Amplification was regarded, since the early days of quantum theory, as a mysterious ingredient that endows quantum microstates with macroscopic consequences, key to the "collapse of the wavepacket", and a way to avoid embarrassing problems exemplified by Schr\\"odinger's cat. Such a bridge between the quantum microworld and the classical world of our experience was postulated ad hoc in the Copenhagen Interpretation. Quantum Darwinism views amplification as replication, in many copies, of the information about quantum states. We show that such amplification is a natural consequence of a broad class of models of decoherence, including the photon environment we use to obtain most of our information. This leads to objective reality via the presence of robust and widely accessible records of selected quantum states. The resulting redundancy (the number of copies deposited in the environment) follows from the Quantum Chernoff Information that quantifies the information transmitted by a typical elementary subsystem of the environment.

Michael Zwolak; C. Jess Riedel; Wojciech H. Zurek

2013-12-18T23:59:59.000Z

128

Is Number of Pregnancies a Risk Factor for Heart Attack in Women?.

??Background: Studies regarding number of pregnancies and coronary heart disease have shown inconsistent results. In the present study, we assessed the association between number of… (more)

Irukulla, Pavan Kumar

2008-01-01T23:59:59.000Z

129

Von Neumann Betti numbers and Novikov type inequalities

It is shown that the Novikov inequalities for critical points of closed 1-forms hold with the von Neumann Betti numbers replacing the Novikov numbers. As a corollary we obtain a vanishing theorem for $L^2$ cohomology, generalizing a theorem of W. Lueck. We also prove that von Neumann Betti numbers coincide with the Novikov numbers for free abelian coverings.

Michael Farber

1998-10-18T23:59:59.000Z

130

Quantum Computing and Hidden Variables Scott Aaronson #

Quantum Computing and Hidden Variables Scott Aaronson # Institute for Advanced Study, Princeton of a hidden variable, then we could e#ciently solve problems that are believed to be intractable even powerful than the quantum computing model. PACS numbers: 03.65.Ta, 03.65.Ud, 03.67.Lx, 02.70.Âc I

Aaronson, Scott

131

Quantum technology and its applications

Quantum states of matter can be exploited as high performance sensors for measuring time, gravity, rotation, and electromagnetic fields, and quantum states of light provide powerful new tools for imaging and communication. Much attention is being paid to the ultimate limits of this quantum technology. For example, it has already been shown that exotic quantum states can be used to measure or image with higher precision or higher resolution or lower radiated power than any conventional technologies, and proof-of-principle experiments demonstrating measurement precision below the standard quantum limit (shot noise) are just starting to appear. However, quantum technologies have another powerful advantage beyond pure sensing performance that may turn out to be more important in practical applications: the potential for building devices with lower size/weight/power (SWaP) and cost requirements than existing instruments. The organizers of Quantum Technology Applications Workshop (QTAW) have several goals: (1) Bring together sponsors, researchers, engineers and end users to help build a stronger quantum technology community; (2) Identify how quantum systems might improve the performance of practical devices in the near- to mid-term; and (3) Identify applications for which more long term investment is necessary to realize improved performance for realistic applications. To realize these goals, the QTAW II workshop included fifty scientists, engineers, managers and sponsors from academia, national laboratories, government and the private-sector. The agenda included twelve presentations, a panel discussion, several breaks for informal exchanges, and a written survey of participants. Topics included photon sources, optics and detectors, squeezed light, matter waves, atomic clocks and atom magnetometry. Corresponding applications included communication, imaging, optical interferometry, navigation, gravimetry, geodesy, biomagnetism, and explosives detection. Participants considered the physics and engineering of quantum and conventional technologies, and how quantum techniques could (or could not) overcome limitations of conventional systems. They identified several auxiliary technologies that needed to be further developed in order to make quantum technology more accessible. Much of the discussion also focused on specific applications of quantum technology and how to push the technology into broader communities, which would in turn identify new uses of the technology. Since our main interest is practical improvement of devices and techniques, we take a liberal definition of 'quantum technology': a system that utilizes preparation and measurement of a well-defined coherent quantum state. This nomenclature encompasses features broader than entanglement, squeezing or quantum correlations, which are often more difficult to utilize outside of a laboratory environment. Still, some applications discussed in the workshop do take advantage of these 'quantum-enhanced' features. They build on the more established quantum technologies that are amenable to manipulation at the quantum level, such as atom magnetometers and atomic clocks. Understanding and developing those technologies through traditional engineering will clarify where quantum-enhanced features can be used most effectively, in addition to providing end users with improved devices in the near-term.

Boshier, Malcolm [Los Alamos National Laboratory; Berkeland, Dana [USG; Govindan, Tr [ARO; Abo - Shaeer, Jamil [DARPA

2010-12-10T23:59:59.000Z

132

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 Böhm…

2001-01-01T23:59:59.000Z

133

Science Journals Connector (OSTI)

Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game—bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow). We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2?1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.

Sadiq Muhammad; Armin Tavakoli; Maciej Kurant; Marcin Paw?owski; Marek ?ukowski; Mohamed Bourennane

2014-06-12T23:59:59.000Z

134

Quantum Interferometric Sensors

Quantum entanglement has the potential to revolutionize the entire field of interferometric sensing by providing many orders of magnitude improvement in interferometer sensitivity. The quantum-entangled particle interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like $1/\\sqrt{N}$, where $N$ is the number of particles passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of $\\sqrt{N}$ to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. This effect can translate into a tremendous science pay-off for space missions. For example, one application of this new effect is to fiber optical gyroscopes for deep-space inertial guidance and tests of General Relativity (Gravity Probe B). Another application is to ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively. Other applications are to Satellite-to-Satellite laser Interferometry (SSI) proposed for the next generation Gravity Recovery And Climate Experiment (GRACE II).

Kishore T. Kapale; Leo D. Didomenico; Hwang Lee; Pieter Kok; Jonathan P. Dowling

2005-07-15T23:59:59.000Z

135

Quantum Entanglement in Carbon Nanotubes

Science Journals Connector (OSTI)

With the surge of research in quantum information, the issue of producing entangled states has gained prominence. Here, we show that judiciously bringing together two systems of strongly interacting electrons with vastly differing ground states—the gapped BCS superconductor and the Luttinger liquid—can result in quantum entanglement. We propose three sets of measurements involving single-walled metallic carbon nanotubes which have been shown to exhibit Luttinger liquid physics, to test our claim and as nanoscience experiments of interest in and of themselves.

Cristina Bena; Smitha Vishveshwara; Leon Balents; Matthew P. A. Fisher

2002-06-26T23:59:59.000Z

136

Physics as quantum information processing

The experience from Quantum Information has lead us to look at Quantum Theory (QT) and the whole Physics from a different angle. The information-theoretical paradigm---"It from Bit'---prophesied by John Archibald Wheeler is relentlessly advancing. Recently it has been shown that QT is derivable from pure informational principles. The possibility that there is only QT at the foundations of Physics has been then considered, with space-time, Relativity, quantization rules and Quantum Field Theory (QFT) emerging from a quantum-information processing. The resulting theory is a discrete version of QFT with automatic relativistic invariance, and without fields, Hamiltonian, and quantization rules. In this paper I review some recent advances on these lines. In particular: i) How space-time and relativistic covariance emerge from the quantum computation; ii) The derivation of the Dirac equation as free information flow, without imposing Lorentz covariance; iii) the information-theoretical meaning of inertial mass and Planck constant; iv) An observable consequence of the theory: a mass-dependent refraction index of vacuum. I will then conclude with two possible routes to Quantum Gravity.

Giacomo Mauro D'Ariano

2010-12-12T23:59:59.000Z

137

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

138

Some Physics And System Issues In The Security Analysis Of Quantum Key Distribution Protocols

In this paper we review a number of issues on the security of quantum key distribution (QKD) protocols that bear directly on the relevant physics or mathematical representation of the QKD cryptosystem. It is shown that the cryptosystem representation itself may miss out many possible attacks which are not accounted for in the security analysis and proofs. Hence the final security claims drawn from such analysis are not reliable, apart from foundational issues about the security criteria that are discussed elsewhere. The cases of continuous-variable QKD and multi-photon sources are elaborated upon.

Horace P. Yuen

2014-05-07T23:59:59.000Z

139

The dissertation argues for the necessity of a morphosemantic theory of number, that is, a theory of number serviceable both to semantics and morphology. The basis for this position, and the empirical core of the dissertation, ...

Harbour, Daniel, 1975-

2003-01-01T23:59:59.000Z

140

A Review of Procedure to Evolve Quantum Procedures

There exist quantum algorithms that are more efficient than their classical counterparts; such algorithms were invented by Shor in 1994 and then Grover in 1996. A lack of invention since Grover's algorithm has been commonly attributed to the non-intuitive nature of quantum algorithms to the classically trained person. Thus, the idea of using computers to automatically generate quantum algorithms based on an evolutionary model emerged. A limitation of this approach is that quantum computers do not yet exist and quantum simulation on a classical machine has an exponential order overhead. Nevertheless, early research into evolving quantum algorithms has shown promise. This paper provides an introduction into quantum and evolutionary algorithms for the computer scientist not familiar with these fields. The exciting field of using evolutionary algorithms to evolve quantum algorithms is then reviewed.

Adrian Gepp; Phil Stocks

2007-08-24T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

141

Quantum walks and quantum simulation of wavepacket dynamics with twisted photons

The "quantum walk" has emerged recently as a paradigmatic process for the dynamic simulation of complex quantum systems, entanglement production and quantum computation. Hitherto, photonic implementations of quantum walks have mainly been based on multi-path interferometric schemes in real space. Here, we report the experimental realization of a discrete quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous photons. In contrast to previous implementations, the whole process develops in a single light beam, with no need of interferometers; it requires optical resources scaling linearly with the number of steps; and it allows flexible control of input and output superposition states. Exploiting the latter property, we also simulated the quantum dynamics of Gaussian wavepackets, exploring the system dispersion relation in momentum space and the associated spin-orbit topological features. Our demonstration introduces a novel versatile photonic platform for quantum simulations.

Filippo Cardano; Francesco Massa; Hammam Qassim; Ebrahim Karimi; Sergei Slussarenko; Domenico Paparo; Corrado de Lisio; Fabio Sciarrino; Enrico Santamato; Robert W. Boyd; Lorenzo Marrucci

2014-07-21T23:59:59.000Z

142

Probing Aerogels by Multiple Quantum Filtered 131Xe NMR Spectroscopy

Science Journals Connector (OSTI)

This is demonstrated in Figure 1 where four pulse sequences using multiple quantum filters are shown. ... Pyrex tube at 7.4 T, 1.2 MPa, and 298 K:? (a) double-quantum filtered pulse sequence, (b) magic-angle double-quantum filter which is a T2,±1 pulse sequence, (c) triple-quantum filtered sequence, and (d) triple-quantum filtered inversion recovery pulse sequence. ... 14-16 The tubes have been filled with aerogel fragments of a few millimeter diameter and were pressurized with xenon to about 6.9 MPa at 298 K to create supercritical conditions. ...

Thomas Meersmann; Michaël Deschamps; Geoffrey Bodenhausen

2001-01-13T23:59:59.000Z

143

Quantum top inside a Bose-Einstein-condensate Josephson junction

We consider an atomic quantum dot confined between two weakly coupled Bose-Einstein condensates, where the dot serves as an additional tunneling channel. It is shown that the thus-embedded atomic quantum dot is a pseudospin subject to an external torque, and therefore equivalent to a quantum top. We demonstrate by numerical analysis of the time-dependent coupled evolution equations that this microscopic quantum top is very sensitive to any deviation from linear oscillatory behavior of the condensates. For sufficiently strong dot-condensate coupling, the atomic quantum dot can induce or modify the tunneling between the macroscopic condensates in the two wells.

Bausmerth, Ingrid; Posazhennikova, Anna [Institut fuer Theoretische Festkoerperphysik, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany); Fischer, Uwe R. [Institut fuer Theoretische Physik, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2007-05-15T23:59:59.000Z

144

Pulsed homodyne Gaussian quantum tomography with low detection efficiency

Pulsed homodyne quantum tomography usually requires a high detection efficiency limiting its applicability in quantum optics. Here, it is shown that the presence of low detection efficiency ($<50\\%$) does not prevent the tomographic reconstruction of quantum states of light, specifically, of Gaussian type. This result is obtained by applying the so-called "minimax" adaptive reconstruction of the Wigner function to pulsed homodyne detection. In particular, we prove, by both numerical and real experiments, that an effective discrimination of different Gaussian quantum states can be achieved. Our finding paves the way to a more extensive use of quantum tomographic methods, even in physical situations in which high detection efficiency is unattainable.

Martina Esposito; Fabio Benatti; Roberto Floreanini; Stefano Olivares; Francesco Randi; Kelvin Titimbo; Marco Pividori; Fabio Novelli; Federico Cilento; Fulvio Parmigiani; Daniele Fausti

2014-02-19T23:59:59.000Z

145

Quantum Certificate Complexity Scott Aaronson #

, that Q 0 (f) # R 0 (f), and that Q E (f) # D (f). If f is partial (i.e. Dom (f) #= {0, 1} n ), then Q 2Quantum Certificate Complexity Scott Aaronson # Computer Science Division University of California . Then the deterministic query complexity D (f) is the minimum number of queries to the y i 's needed to evaluate f , if Y

Aaronson, Scott

146

A model for a quantum heat bath is introduced. When the bath molecules have finitely many degrees of freedom, it is shown that the assumption that the molecules are weakly interacting is sufficient to enable one to derive the canonical distribution for the energy of a small system immersed in the bath. While the specific form of the bath temperature, for which we provide an explicit formula, depends on (i) spectral properties of the bath molecules, and (ii) the choice of probability measure on the state space of the bath, we are in all cases able to establish the existence of a strictly positive lower bound on the temperature of the bath. The results can be used to test the merits of different hypotheses for the equilibrium states of quantum systems. Two examples of physically plausible choices for the probability measure on the state space of a quantum heat bath are considered in detail, and the associated lower bounds on the temperature of the bath are worked out.

Dorje C. Brody; Lane P. Hughston

2014-11-17T23:59:59.000Z

147

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

148

It is considered the indirect inter-qubit coupling in 1D chain of atoms with nuclear spins 1/2, which plays role of qubits in the quantum register. This chain of the atoms is placed by regular way in easy-axis 3D antiferromagnetic thin plate substrate, which is cleaned from the other nuclear spin containing isotopes. It is shown that the range of indirect inter-spin coupling may run to a great number of lattice constants both near critical point of quantum phase transition in antiferromagnet of spin-flop type (control parameter is external magnetic field) and/or near homogeneous antiferromagnetic resonance (control parameter is microwave frequency).

A. A. Kokin

2004-10-31T23:59:59.000Z

149

Office of Scientific and Technical Information (OSTI)

The images are processed through Adobe Photoshop to determine the amount of white light, thus the quantity of Glo Germ powder. The coupon shown in the picture in Figure...

150

On the Nature of Quantum Phenomena

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

151

Quantum Mechanical Search and Harmonic Perturbation

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

152

Nuclear quantum effects in water

In this work, a path integral Car-Parrinello molecular dynamics simulation of liquid water is performed. It is found that the inclusion of nuclear quantum effects systematically improves the agreement of first principles simulations of liquid water with experiment. In addition, the proton momentum distribution is computed utilizing a recently developed open path integral molecular dynamics methodology. It is shown that these results are in good agreement with neutron Compton scattering data for liquid water and ice.

Joseph A. Morrone; Roberto Car

2008-03-25T23:59:59.000Z

153

Quantum coherence in two dimensions

Science Journals Connector (OSTI)

The formation and evaporation of two-dimensional black holes are discussed. It is shown that if the radiation in minimal scalars has positive energy, there must be a global event horizon or a naked singularity. The former would imply loss of quantum coherence while the latter would lead to an even worse breakdown of predictability. CPT invariance would suggest that there ought to be past horizons as well. A way in which this could happen with wormholes is described.

S. W. Hawking and J. D. Hayward

1994-05-15T23:59:59.000Z

154

Quantum Catalysis of Magnetic Phase Transitions in a Quantum Simulator

We control quantum fluctuations to create the ground state magnetic phases of a classical Ising model with a tunable longitudinal magnetic field using a system of 6 to 10 atomic ion spins. Due to the long-range Ising interactions, the various ground state spin configurations are separated by multiple first-order phase transitions, which in our zero temperature system cannot be driven by thermal fluctuations. We instead use a transverse magnetic field as a quantum catalyst to observe the first steps of the complete fractal devil's staircase, which emerges in the thermodynamic limit and can be mapped to a large number of many-body and energy-optimization problems.

Philip Richerme; Crystal Senko; Simcha Korenblit; Jacob Smith; Aaron Lee; Rajibul Islam; Wesley C. Campbell; Christopher Monroe

2013-03-27T23:59:59.000Z

155

Graph isomorphism and adiabatic quantum computing

Science Journals Connector (OSTI)

In the graph isomorphism (GI) problem two N-vertex graphs G and G? are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and transforms G?G?. If yes, then G and G? are said to be isomorphic; otherwise they are nonisomorphic. The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. In this paper we present a quantum algorithm that solves arbitrary instances of GI and which also provides an approach to determining all automorphisms of a given graph. We show how the GI problem can be converted to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. We numerically simulate the algorithm's quantum dynamics and show that it correctly (i) distinguishes nonisomorphic graphs; (ii) recognizes isomorphic graphs and determines the permutation(s) that connect them; and (iii) finds the automorphism group of a given graph G. We then discuss the GI quantum algorithm's experimental implementation, and close by showing how it can be leveraged to give a quantum algorithm that solves arbitrary instances of the NP-complete subgraph isomorphism problem. The computational complexity of an adiabatic quantum algorithm is largely determined by the minimum energy gap ?(N) separating the ground and first-excited states in the limit of large problem size N?1. Calculating ?(N) in this limit is a fundamental open problem in adiabatic quantum computing, and so it is not possible to determine the computational complexity of adiabatic quantum algorithms in general, nor consequently, of the specific adiabatic quantum algorithms presented here. Adiabatic quantum computing has been shown to be equivalent to the circuit model of quantum computing, and so development of adiabatic quantum algorithms continues to be of great interest.

Frank Gaitan and Lane Clark

2014-02-28T23:59:59.000Z

156

Stochastic quantization weakening and quantum entanglement decoherence

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

157

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

158

On Quantum Algorithm for Binary Search and Its Computational Complexity

A new quantum algorithm for a search problem and its computational complexity are discussed. It is shown in the search problem containing 2^n objects that our algorithm runs in polynomial time.

S. Iriyama; M. Ohya; I. V. Volovich

2013-06-21T23:59:59.000Z

159

Commutators in Quantum Hydrodynamics for Interacting Bose Systems

Science Journals Connector (OSTI)

It is shown that the curl of the velocity operator in the second quantized version of quantum hydrodynamics for interacting Bose systems is equal to zero, thus resolving the apparent discrepancies between various existing formulations.

Robert Fanelli and R. E. Struzynski

1969-06-05T23:59:59.000Z

160

Hybrid cluster state proposal for a quantum game

We propose an experimental implementation of a quantum game algorithm in a hybrid scheme combining the quantum circuit approach and the cluster state model. An economical cluster configuration is suggested to embody a quantum version of the Prisoners' Dilemma. Our proposal is shown to be within the experimental state-of-art and can be realized with existing technology. The effects of relevant experimental imperfections are also carefully examined.

M. Paternostro; M. S. Tame; M. S. Kim

2005-09-09T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

161

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

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

162

Quantum arithmetic with the Quantum Fourier Transform

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

163

Producibility in hierarchical self-assembly David Doty Abstract Three results are shown on producibility in the hierarchical model of tile self-assembly. It is shown that a simple greedy polynomial, an assembly is considered terminal if nothing can attach to it; viewing self-assembly as a computation

Doty, David

164

Physics as Quantum Information Processing: Quantum Fields as Quantum Automata

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

165

Quantum coherence and correlations in quantum system

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

166

Many-body entanglement in gapped quantum systems : representation, classification, and application

Entanglement is a special form of quantum correlation that exists among quantum particles and it has been realized that surprising things can happen when a large number of particles are entangled together. For example, ...

Chen, Xie, Ph. D. Massachusetts Institute of Technology

2012-01-01T23:59:59.000Z

167

Quantum computer of wire circuit architecture

First solid state quantum computer was built using transmons (cooper pair boxes). The operation of the computer is limited because of using a number of the rigit cooper boxes working with fixed frequency at temperatures of superconducting material. Here, we propose a novel architecture of quantum computer based on a flexible wire circuit of many coupled quantum nodes containing controlled atomic (molecular) ensembles. We demonstrate wide opportunities of the proposed computer. Firstly, we reveal a perfect storage of external photon qubits to multi-mode quantum memory node and demonstrate a reversible exchange of the qubits between any arbitrary nodes. We found optimal parameters of atoms in the circuit and self quantum modes for quantum processing. The predicted perfect storage has been observed experimentally for microwave radiation on the lithium phthalocyaninate molecule ensemble. Then also, for the first time we show a realization of the efficient basic two-qubit gate with direct coupling of two arbitrary nodes by using appropriate atomic frequency shifts in the circuit nodes. Proposed two-qubit gate runs with a speed drastically accelerated proportionally to the number of atoms in the node. The direct coupling and accelerated two-qubit gate can be realized for large number of the circuit nodes. Finally, we describe two and three-dimensional scalable architectures that pave the road to construction of universal multi-qubit quantum computer operating at room temperatures.

S. A. Moiseev; F. F. Gubaidullin; S. N. Andrianov

2010-01-07T23:59:59.000Z

168

An avalanche-photodiode-based photon-number-resolving detector

Avalanche photodiodes are widely used as practical detectors of single photons.1 Although conventional devices respond to one or more photons, they cannot resolve the number in the incident pulse or short time interval. However, such photon number resolving detectors are urgently needed for applications in quantum computing,2-4 communications5 and interferometry,6 as well as for extending the applicability of quantum detection generally. Here we show that, contrary to current belief,3,4 avalanche photodiodes are capable of detecting photon number, using a technique to measure very weak avalanches at the early stage of their development. Under such conditions the output signal from the avalanche photodiode is proportional to the number of photons in the incident pulse. As a compact, mass-manufactured device, operating without cryogens and at telecom wavelengths, it offers a practical solution for photon number detection.

B. E. Kardynal; Z. L. Yuan; A. J. Shields

2008-07-02T23:59:59.000Z

169

Ising quantum chain and sequence evolution Holger Wagner 1) , Ellen Baake 2) , and Thomas Gerisch 1)

Ising quantum chain and sequence evolution Holger Wagner 1) , Ellen Baake 2) , and Thomas Gerisch 1 in molecular evolution is shown to be equivalent to an Ising quantum chain. Observable quantities, tailored and selection; Ising quantum chain; mean-#12;eld model; phase transition 1 Introduction Sequence space models

Baake, Ellen

170

Quantum computing in a piece of glass

Quantum gates and simple quantum algorithms can be designed utilizing the diffraction phenomena of a photon within a multiplexed holographic element. The quantum eigenstates we use are the photon's linear momentum (LM) as measured by the number of waves of tilt across the aperture. Two properties of quantum computing within the circuit model make this approach attractive. First, any conditional measurement can be commuted in time with any unitary quantum gate - the timeless nature of quantum computing. Second, photon entanglement can be encoded as a superposition state of a single photon in a higher-dimensional state space afforded by LM. Our theoretical and numerical results indicate that OptiGrate's photo-thermal refractive (PTR) glass is an enabling technology. We will review our previous design of a quantum projection operator and give credence to this approach on a representative quantum gate grounded on coupled-mode theory and numerical simulations, all with parameters consistent with PTR glass. We discuss the strengths (high efficiencies, robustness to environment) and limitations (scalability, crosstalk) of this technology. While not scalable, the utility and robustness of such optical elements for broader quantum information processing applications can be substantial.

Warner A. Miller; Grigoriy Kreymerman; Christopher Tison; Paul M. Alsing; Jonathan R. McDonald

2011-12-15T23:59:59.000Z

171

Surface electromagnetic wave equations in a warm magnetized quantum plasma

Based on the single-fluid plasma model, a theoretical investigation of surface electromagnetic waves in a warm quantum magnetized inhomogeneous plasma is presented. The surface electromagnetic waves are assumed to propagate on the plane between a vacuum and a warm quantum magnetized plasma. The quantum magnetohydrodynamic model includes quantum diffraction effect (Bohm potential), and quantum statistical pressure is used to derive the new dispersion relation of surface electromagnetic waves. And the general dispersion relation is analyzed in some special cases of interest. It is shown that surface plasma oscillations can be propagated due to quantum effects, and the propagation velocity is enhanced. Furthermore, the external magnetic field has a significant effect on surface wave's dispersion equation. Our work should be of a useful tool for investigating the physical characteristic of surface waves and physical properties of the bounded quantum plasmas.

Li, Chunhua; Yang, Weihong [Department of Modern Physics, University of Science and Technology of China, 230026 Hefei (China); Wu, Zhengwei, E-mail: wuzw@ustc.edu.cn [Department of Modern Physics, University of Science and Technology of China, 230026 Hefei (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Center of Low Temperature Plasma Application, Yunnan Aerospace Industry Company, Kunming, 650229 Yunnan (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

2014-07-15T23:59:59.000Z

172

Modeling of the quantum dot filling and the dark current of quantum dot infrared photodetectors

A generalized drift-diffusion model for the calculation of both the quantum dot filling profile and the dark current of quantum dot infrared photodetectors is proposed. The confined electrons inside the quantum dots produce a space-charge potential barrier between the two contacts, which controls the quantum dot filling and limits the dark current in the device. The results of the model reasonably agree with a published experimental work. It is found that increasing either the doping level or the temperature results in an exponential increase of the dark current. The quantum dot filling turns out to be nonuniform, with a dot near the contacts containing more electrons than one in the middle of the device where the dot occupation approximately equals the number of doping atoms per dot, which means that quantum dots away from contacts will be nearly unoccupied if the active region is undoped.

Ameen, Tarek A.; El-Batawy, Yasser M.; Abouelsaood, A. A. [Department of Engineering Mathematics and Physics, Faculty of Engineering, Cairo University, Giza (Egypt)

2014-02-14T23:59:59.000Z

173

Quantum and classical separability of spin-orbit laser modes

In this work we investigate the quantum noise properties of polarization vortices in connection with an intensity based Clauser-Horne-Shimony-Holt inequality for their spin-orbit separability. We evaluate the inequality for different input quantum states and the corresponding intensity fluctuations. The roles played by coherence and photon number squeezing provide a suitable framework for characterizing pure state spin-orbit entanglement. Structural inseparability of the spin-orbit mode requires coherence, an issue concerning either classical or quantum descriptions. In both cases, it can be witnessed by violation of this intensity based CHSH inequality. However, in the quantum domain, entanglement requires both coherence and reduced photon number fluctuations.

L. J. Pereira; A. Z. Khoury; K. Dechoum

2014-09-02T23:59:59.000Z

174

Construction of relativistic quantum theory: a progress report

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

175

Subsidiary Condition in Quantum Electrodynamics

Science Journals Connector (OSTI)

The subsidiary condition ?A?(+)?x?|n?=0, usually known as the "Gupta-Bleuler" condition, is shown to be inadequate as a criterion for defining physical states in quantum electrodynamics in the Lorentz gauge. The condition is shown not to be covariant and to fail to define state vectors that remain in the physical subspace. An alternative subsidiary condition, which is satisfactory, is discussed and is shown to require an extensively different formulation of the collision problem in quantum electrodynamics. Some possible physical consequences of the inadequacy of ?A?(+)?x?|n?=0 are proposed; these include effects in the decays of short-lived particles, and the fact that in some types of strong interactions, acting simultaneously with electromagnetic ones, S-matrix elements may occur which predict transitions from the physical space into the part of space in which the subsidiary condition is violated. The solution to the collision problem for stable charged particles that have only electromagnetic interactions is shown to be identical to that obtainable from the present theory.

Kurt Haller and Leon F. Landovitz

1968-07-25T23:59:59.000Z

176

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

177

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

178

A bridge to lower overhead quantum computation

Two primary challenges stand in the way of practical large-scale quantum computation, namely achieving sufficiently low error rate quantum gates and implementing interesting quantum algorithms with a physically reasonable number of qubits. In this work we address the second challenge, presenting a new technique, bridge compression, which enables remarkably low volume structures to be found that implement complex computations in the surface code. The surface code has a number of highly desirable properties, including the ability to achieve arbitrarily reliable computation given sufficient qubits and quantum gate error rates below approximately 1%, and the use of only a 2-D array of qubits with nearest neighbor interactions. As such, our compression technique is of great practical relevance.

Austin G. Fowler; Simon J. Devitt

2012-09-04T23:59:59.000Z

179

Replication Regulates Volume Weighting in Quantum Cosmology

Probabilities for observations in cosmology are conditioned both on the universe's quantum state and on local data specifying the observational situation. We show the quantum state defines a measure for prediction through such conditional probabilities that is well behaved for spatially large or infinite universes when the probabilities that our data is replicated are taken into account. In histories where our data are rare volume weighting connects top-down probabilities conditioned on both the data and the quantum state to the bottom-up probabilities conditioned on the quantum state alone. We apply these principles to a calculation of the number of inflationary e-folds in a homogeneous, isotropic minisuperspace model with a single scalar field moving in a quadratic potential. We find that volume weighting is justified and the top-down probabilities favor a large number of e-folds.

James Hartle; Thomas Hertog

2009-05-24T23:59:59.000Z

180

Insulator Formed by Quantum Vortices in Josephson Junction Arrays Alexander van Oudenaarden and J. E. Mooij) The quantum transport of vortices in very long and narrow arrays of small Josephson junctions has been studied-range interactions. Experi- mentally, Josephson junction arrays can be used to study interacting bosons in one

van Oudenaarden, Alexander

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

181

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

182

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

183

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

184

Energy Content of Quantum Systems and the Alleged Collapse of the Wavefunction

It is shown that within a quantum system, the wave field has a (potential) energy content that can be exchanged with quantum particles. Energy conservation in quantum systems holds if potential energy is correctly taken to be a field attribute. From this perspective, a transfer of energy occurs on measurement from the wave field to a quantum particle and this provides a physical explanation of what is commonly referred to as the collapse of the wavefunction.

Peter J. Riggs

2009-10-15T23:59:59.000Z

185

Solving for the Particle-Number-Projected HFB Wavefunction

Recently we proposed a particle-number-conserving theory for nuclear pairing [Jia, Phys. Rev. C 88, 044303 (2013)] through the generalized density matrix formalism. The relevant equations were solved for the case when each single-particle level has a distinct set of quantum numbers and could only pair with its time-reversed partner (BCS-type Hamiltonian). In this work we consider the more general situation when several single-particle levels could have the same set of quantum numbers and pairing among these levels is allowed (HFB-type Hamiltonian). The pair condensate wavefunction (the HFB wavefunction projected onto good particle number) is determined by the equations of motion for density matrix operators instead of the variation principle. The theory is tested in the simple two-level model with factorizable pairing interactions and the semi-realistic model with the zero-range delta interaction.

Jia, L Y

2015-01-01T23:59:59.000Z

186

“Quantum Coaxial Cables” for Solar Energy Harvesting

Science Journals Connector (OSTI)

“Quantum Coaxial Cables” for Solar Energy Harvesting ... A conventional coaxial cable is a two-conductor cable consisting of a central wire conductor symmetrically surrounded by a braided conductor with an insulating spacer in between, as shown in Figure 1a. ...

Yong Zhang; Lin-Wang Wang; Angelo Mascarenhas

2007-04-05T23:59:59.000Z

187

Effect of carrier dynamics and temperature on two-state lasing in semiconductor quantum dot lasers

It is analytically shown that the both the charge carrier dynamics in quantum dots and their capture into the quantum dots from the matrix material have a significant effect on two-state lasing phenomenon in quantum dot lasers. In particular, the consideration of desynchronization in electron and hole capture into quantum dots allows one to describe the quenching of ground-state lasing observed at high injection currents both qualitatevely and quantitatively. At the same time, an analysis of the charge carrier dynamics in a single quantum dot allowed us to describe the temperature dependences of the emission power via the ground- and excited-state optical transitions of quantum dots.

Korenev, V. V., E-mail: korenev@spbau.ru; Savelyev, A. V.; Zhukov, A. E.; Omelchenko, A. V.; Maximov, M. V. [Saint Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation)] [Saint Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation)

2013-10-15T23:59:59.000Z

188

Elementary quantum cloning machines

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

189

Location-dependent communications using quantum entanglement

The ability to unconditionally verify the location of a communication receiver would lead to a wide range of new security paradigms. However, it is known that unconditional location verification in classical communication systems is impossible. In this work we show how unconditional location verification can be achieved with the use of quantum communication channels. Our verification remains unconditional irrespective of the number of receivers, computational capacity, or any other physical resource held by an adversary. Quantum location verification represents an application of quantum entanglement that delivers a feat not possible in the classical-only channel. It gives us the ability to deliver real-time communications viable only at specified geographical coordinates.

Malaney, Robert A. [School of Electrical Engineering and Telecommunications, University of New South Wales, New South Wales 2052 (Australia)

2010-04-15T23:59:59.000Z

190

Resonator-quantum well infrared photodetectors

We applied a recent electromagnetic model to design the resonator-quantum well infrared photodetector (R-QWIP). In this design, we used an array of rings as diffractive elements to diffract normal incident light into parallel propagation and used the pixel volume as a resonator to intensify the diffracted light. With a proper pixel size, the detector resonates at certain optical wavelengths and thus yields a high quantum efficiency (QE). To test this detector concept, we fabricated a number of R-QWIPs with different quantum well materials and detector geometries. The experimental result agrees satisfactorily with the prediction, and the highest QE achieved is 71%.

Choi, K. K., E-mail: kwong.k.choi.civ@mail.mil; Sun, J.; Olver, K. [Electro-Optics and Photonics Division, U.S. Army Research Laboratory, Adelphi, Maryland 20783 (United States)] [Electro-Optics and Photonics Division, U.S. Army Research Laboratory, Adelphi, Maryland 20783 (United States); Jhabvala, M. D.; Jhabvala, C. A.; Waczynski, A. [Instrument Systems and Technology Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)] [Instrument Systems and Technology Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

2013-11-11T23:59:59.000Z

191

How red is a quantum black hole?

Radiating black holes pose a number of puzzles for semiclassical and quantum gravity. These include the transplanckian problem -- the nearly infinite energies of Hawking particles created near the horizon, and the final state of evaporation. A definitive resolution of these questions likely requires robust inputs from quantum gravity. We argue that one such input is a quantum bound on curvature. We show how this leads to an upper limit on the redshift of a Hawking emitted particle, to a maximum temperature for a black hole, and to the prediction of a Planck scale remnant.

Viqar Husain; Oliver Winkler

2005-05-30T23:59:59.000Z

192

Number | Open Energy Information

Number Number Jump to: navigation, search Properties of type "Number" Showing 200 properties using this type. (previous 200) (next 200) A Property:AvgAnnlGrossOpCpcty Property:AvgTempGeoFluidIntoPlant Property:AvgWellDepth B Property:Building/FloorAreaChurchesChapels Property:Building/FloorAreaGroceryShops Property:Building/FloorAreaHealthServices24hr Property:Building/FloorAreaHealthServicesDaytime Property:Building/FloorAreaHeatedGarages Property:Building/FloorAreaHotels Property:Building/FloorAreaMiscellaneous Property:Building/FloorAreaOffices Property:Building/FloorAreaOtherRetail Property:Building/FloorAreaResidential Property:Building/FloorAreaRestaurants Property:Building/FloorAreaSchoolsChildDayCare Property:Building/FloorAreaShops Property:Building/FloorAreaSportCenters

193

All beams of electromagnetic radiation are made of photons. Therefore, it is important to find a precise relationship between the classical properties of the beam and the quantum characteristics of the photons that make a particular beam. It is shown that this relationship is best expressed in terms of the Riemann-Silberstein vector -- a complex combination of the electric and magnetic field vectors -- that plays the role of the photon wave function. The Whittaker representation of this vector in terms of a single complex function satisfying the wave equation greatly simplifies the analysis. Bessel beams, exact Laguerre-Gauss beams, and other related beams of electromagnetic radiation can be described in a unified fashion. The appropriate photon quantum numbers for these beams are identified. Special emphasis is put on the angular momentum of a single photon and its connection with the angular momentum of the beam.

Iwo Bialynicki-Birula; Zofia Bialynicka-Birula

2006-01-12T23:59:59.000Z

194

Compressed Quantum Simulation of the Ising Model

Science Journals Connector (OSTI)

Jozsa et al. [Proc. R. Soc. A 466, 809 2009)] have shown that a match gate circuit running on n qubits can be compressed to a universal quantum computation on log?(n)+3 qubits. Here, we show how this compression can be employed to simulate the Ising interaction of a 1D chain consisting of n qubits using a universal quantum computer running on log?(n) qubits. We demonstrate how the adiabatic evolution can be realized on this exponentially smaller system and how the magnetization, which displays a quantum phase transition, can be measured. This shows that the quantum phase transition of very large systems can be observed experimentally with current technology.

B. Kraus

2011-12-14T23:59:59.000Z

195

Quantum mechanical stabilization of Minkowski signature wormholes

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

196

Quantum memory in non-inertial frames

We study the effect of quantum memory in non-inertial frames under the influence of amplitude damping, depolarizing, phase flip and bit-phase flip channels. It is shown that the entanglement of initial state is heavily influenced by quantum correlations. It is seen that quantum memory compensates the loss of entanglement generated caused by the Unruh effect. It is interesting to note that the sudden death of entanglement disappears for any acceleration for higher values of memory. Therefore, it is possible to avoid ESD in non-inertial frames due to the presence of quantum memory. Furthermore, the degree of entanglement is enhanced as we increase the degree of memory and it maximizes for maximum correlations.

M. Ramzan; M. K. Khan

2011-01-15T23:59:59.000Z

197

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

198

OptQC: An optimised parallel quantum compiler

The software package \\emph{Qcompiler} (CPC, 184 (2013) 853) provides a general quantum compilation framework, which maps any given unitary operation into a quantum circuit consisting of a sequential set of elementary quantum gates. In this paper, we present an extended software \\emph{OptQC}, which finds permutation matrices $P$ and $Q$ for a given unitary matrix $U$ such that the number of gates in the quantum circuit of $U = Q^TP^TU'PQ$ is significantly reduced, where $U'$ is equivalent to $U$ up to a permutation and the quantum circuit implementation of each matrix component is considered separately. We extend further this software package to make use of high-performance computers with a multiprocessor architecture using MPI. We demonstrate its effectiveness in reducing the total number of quantum gates required for various unitary operators.

T. Loke; J. B. Wang

2014-08-07T23:59:59.000Z

199

Simulating weak localization using superconducting quantum circuits

Understanding complex quantum matter presents a central challenge in condensed matter physics. The difficulty lies in the exponential scaling of the Hilbert space with the system size, making solutions intractable for both analytical and conventional numerical methods. As originally envisioned by Richard Feynman, this class of problems can be tackled using controllable quantum simulators. Despite many efforts, building an quantum emulator capable of solving generic quantum problems remains an outstanding challenge, as this involves controlling a large number of quantum elements. Here, employing a multi-element superconducting quantum circuit and manipulating a single microwave photon, we demonstrate that we can simulate the weak localization phenomenon observed in mesoscopic systems. By engineering the control sequence in our emulator circuit, we are also able to reproduce the well-known temperature dependence of weak localization. Furthermore, we can use our circuit to continuously tune the level of disorder, a parameter that is not readily accessible in mesoscopic systems. By demonstrating a high level of control and complexity, our experiment shows the potential for superconducting quantum circuits to realize scalable quantum simulators.

Yu Chen; P. Roushan; D. Sank; C. Neill; Erik Lucero; Matteo Mariantoni; R. Barends; B. Chiaro; J. Kelly; A. Megrant; J. Y. Mutus; P. J. J. O'Malley; A. Vainsencher; J. Wenner; T. C. White; Yi Yin; A. N. Cleland; John M. Martinis

2014-03-26T23:59:59.000Z

200

Quantum Certificate Complexity Scott Aaronson #

(f) # D (f ), and that Q 0 (f) # R 0 (f). 1 If f is partial (i.e. S #= {0, 1} n ), then Q 2 (f) canQuantum Certificate Complexity Scott Aaronson # Abstract Given a Boolean function f , we study two . Then the deterministic query complexity D (f) is the minimum number of queries to the y i 's needed to evaluate f , if Y

Aaronson, Scott

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

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201

This document contains information dealing with the lessons learned from the experience of nuclear plants. In this issue the authors tried to avoid the `tyranny` of numbers and concentrated on the main lessons learned. Topics include: filtration devices for air pollution abatement, crack repair and inspection, and remote handling equipment.

Khan, T.A.; Baum, J.W.; Beckman, M.C. [eds.] [eds.

1993-10-01T23:59:59.000Z

202

Science Journals Connector (OSTI)

...variables for which the double inte-gral does not exist: R. L. JEFFERY. On the number of elements in a group which have a power in...society will meet at Columbia University, MA ay 2, 1925. W. BENJAMIN FITE Acting Secretary 424 SCIENCE

Theophilus S. Painter

1925-04-17T23:59:59.000Z

203

This report, prepared for the Community Planning Study - Snowmass 2013 - summarizes the theoretical motivations and the experimental efforts to search for baryon number violation, focussing on nucleon decay and neutron-antineutron oscillations. Present and future nucleon decay search experiments using large underground detectors, as well as planned neutron-antineutron oscillation search experiments with free neutron beams are highlighted.

K. S. Babu; E. Kearns; U. Al-Binni; S. Banerjee; D. V. Baxter; Z. Berezhiani; M. Bergevin; S. Bhattacharya; S. Brice; R. Brock; T. W. Burgess; L. Castellanos; S. Chattopadhyay; M-C. Chen; E. Church; C. E. Coppola; D. F. Cowen; R. Cowsik; J. A. Crabtree; H. Davoudiasl; R. Dermisek; A. Dolgov; B. Dutta; G. Dvali; P. Ferguson; P. Fileviez Perez; T. Gabriel; A. Gal; F. Gallmeier; K. S. Ganezer; I. Gogoladze; E. S. Golubeva; V. B. Graves; G. Greene; T. Handler; B. Hartfiel; A. Hawari; L. Heilbronn; J. Hill; D. Jaffe; C. Johnson; C. K. Jung; Y. Kamyshkov; B. Kerbikov; B. Z. Kopeliovich; V. B. Kopeliovich; W. Korsch; T. Lachenmaier; P. Langacker; C-Y. Liu; W. J. Marciano; M. Mocko; R. N. Mohapatra; N. Mokhov; G. Muhrer; P. Mumm; P. Nath; Y. Obayashi; L. Okun; J. C. Pati; R. W. Pattie Jr.; D. G. Phillips II; C. Quigg; J. L. Raaf; S. Raby; E. Ramberg; A. Ray; A. Roy; A. Ruggles; U. Sarkar; A. Saunders; A. Serebrov; Q. Shafi; H. Shimizu; M. Shiozawa; R. Shrock; A. K. Sikdar; W. M. Snow; A. Soha; S. Spanier; G. C. Stavenga; S. Striganov; R. Svoboda; Z. Tang; Z. Tavartkiladze; L. Townsend; S. Tulin; A. Vainshtein; R. Van Kooten; C. E. M. Wagner; Z. Wang; B. Wehring; R. J. Wilson; M. Wise; M. Yokoyama; A. R. Young

2013-11-21T23:59:59.000Z

204

CHEMICAL SAFETY Emergency Numbers

- 1 - CHEMICAL SAFETY MANUAL 2010 #12;- 2 - Emergency Numbers UNBC Prince George Campus Security Prince George Campus Chemstores 6472 Chemical Safety 6472 Radiation Safety 5530 Biological Safety 5530 Risk and Safety Manager 5535 Security 7058 #12;- 3 - FOREWORD This reference manual outlines the safe

Bolch, Tobias

205

Electroweak strings, zero modes and baryon number

Science Journals Connector (OSTI)

The Dirac equations for leptons and quarks in the background of an electroweak Z—string have zero mode solutions. If two loops of electroweak string are linked, the zero modes on one of the loops interacts with the other loop via an Aharanov-Bohm interaction. The effects of this interaction are briefly discussed and it is shown that the fermions induce a baryon number on linked loops of Z—string.

Tanmay Vachaspati

1995-01-01T23:59:59.000Z

206

Entanglement Distillation Protocols and Number Theory

We show that the analysis of entanglement distillation protocols for qudits of arbitrary dimension $D$ benefits from applying basic concepts from number theory, since the set $\\zdn$ associated to Bell diagonal states is a module rather than a vector space. We find that a partition of $\\zdn$ into divisor classes characterizes the invariant properties of mixed Bell diagonal states under local permutations. We construct a very general class of recursion protocols by means of unitary operations implementing these local permutations. We study these distillation protocols depending on whether we use twirling operations in the intermediate steps or not, and we study them both analitically and numerically with Monte Carlo methods. In the absence of twirling operations, we construct extensions of the quantum privacy algorithms valid for secure communications with qudits of any dimension $D$. When $D$ is a prime number, we show that distillation protocols are optimal both qualitatively and quantitatively.

H. Bombin; M. A. Martin-Delgado

2005-03-01T23:59:59.000Z

207

Entanglement distillation protocols and number theory

We show that the analysis of entanglement distillation protocols for qudits of arbitrary dimension D benefits from applying basic concepts from number theory, since the set Z{sub D}{sup n} associated with Bell diagonal states is a module rather than a vector space. We find that a partition of Z{sub D}{sup n} into divisor classes characterizes the invariant properties of mixed Bell diagonal states under local permutations. We construct a very general class of recursion protocols by means of unitary operations implementing these local permutations. We study these distillation protocols depending on whether we use twirling operations in the intermediate steps or not, and we study them both analytically and numerically with Monte Carlo methods. In the absence of twirling operations, we construct extensions of the quantum privacy algorithms valid for secure communications with qudits of any dimension D. When D is a prime number, we show that distillation protocols are optimal both qualitatively and quantitatively.

Bombin, H.; Martin-Delgado, M.A. [Departamento de Fisica Teorica I, Universidad Complutense, 28040 Madrid (Spain)

2005-09-15T23:59:59.000Z

208

Quantum Catalysis of Magnetic Phase Transitions in a Quantum Simulator P. Richerme,1

a transverse magnetic field as a quantum catalyst to observe the first steps of the complete fractal devil's staircase, which emerges in the thermodynamic limit and can be mapped to a large number of many on to a number of energy minimization problems [25,26], and shows the first steps of the complete devil

Richerme, Phil

209

Extractable work from ensembles of quantum batteries. Entanglement helps

Motivated by the recent interest in thermodynamics of micro- and mesoscopic quantum systems we study the maximal amount of work that can be reversibly extracted from a quantum system used to store temporarily energy. Guided by the notion of passivity of a quantum state we show that entangling unitary controls extract in general more work than independent ones. In the limit of large number of copies one can reach the thermodynamical bound given by the variational principle for free energy.

Robert Alicki; Mark Fannes

2012-11-19T23:59:59.000Z

210

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

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 Gonçalves

2014-02-05T23:59:59.000Z

211

Minor in Psychology The minor in Psychology requires 18 hours of Psychology coursework as shown on this minor check sheet may be counted toward the Psychology minor. Research Methods/Critical Thinking Skills 1 PSYC Course - 3 hours Term Grade Hrs Qpts General Psychology Lecture (PSYC 1101) with a C

Raja, Anita

212

Employment in Quebec's forest industry has shown considerable variation during the last few decades productivity of Quebec mills and processing facilities, and increasing foreign competition. Over the past forty years, crises in Quebec's forest industry have mostly been related to variations in oil price

Asselin, Hugo

213

concentrations were similar between yeast lines (data not shown). Analysis of boron concentration Determination and boron translocation in sunflower using the stable isotopes 10 B and 11 B. Aust. J. Plant Physiol. 27respectively. In media with glucose (GAL1 promoter inactive), both soluble and bound boron

CzÃ¡rÃ¡n, TamÃ¡s

214

#12;THE `TEST STATISTICS REPORT' provides a synopsis of the test attributes and some important statistics. A sample is shown here to the right. The Test reliability indicators are measures of how well: Are formulae for testing reliability as a measure of internal consistency. Higher values indicate a stronger

Kambhampati, Patanjali

215

A quick tour through PREKIN (shown for the PC) Double clicking on the PREKIN icon will open the file name. Many programs use PDB files, so they may have a variety of icons. Here I have selected 1CF3 started this session by dragging the icon for your PDB file onto the PREKIN icon, you will bypass both

Richardson, David

216

Installing JBuilder 4 Foundation from the Student CD-ROM 1. Open the My Computer icon on the Window, as shown in Figure 1. 2. Right-click the CD-ROM icon (labeled JAVAWJB4) and choose Open to display the CD-ROM

Liang, Y. Daniel

217

Occupants are in italics to distinguish them from building names; they are shown against the building housing their main reception. Highlighted buildings are those pictured overleaf. If you have a question or comment about the accessibility of the buildings or grounds at the University of Leeds, email

Haase, Markus

218

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

219

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

220

Hybrid quantum devices and quantum engineering

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

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221

ELECTRICAL DISTRICT NUMBER EIGHT

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

ELECTRICAL DISTRICT NUMBER EIGHT ELECTRICAL DISTRICT NUMBER EIGHT Board of Directors Reply to: Ronald Rayner C. W. Adams James D. Downing, P.E. Chairman Billy Hickman 66768 Hwy 60 Brian Turner Marvin John P.O. Box 99 Vice-Chairman Jason Pierce Salome, AZ 85348 Denton Ross Jerry Rovey Secretary James N. Warkomski ED8@HARCUVARCO.COM John Utz Gary Wood PHONE:(928) 859-3647 Treasurer FAX: (928) 859-3145 Sent via e-mail Mr. Darrick Moe, Regional Manager Western Area Power Administration Desert Southwest Region P. O. Box 6457 Phoenix, AZ 85005-6457 moe@wapa.gov; dswpwrmrk@wapa.gov Re: ED5-Palo Verde Hub Project Dear Mr. Moe, In response to the request for comments issued at the October 6 Parker-Davis Project customer th meeting, and in conjunction with comments previously submitted by the Southwest Public Power

222

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8 Preventive Action Report Planning Worksheet 11_0414 1 of 3 8 Preventive Action Report Planning Worksheet 11_0414 1 of 3 EOTA - Business Form Document Title: Preventive Action Report Planning Worksheet Document Number: F-018 Rev 11_0414 Document Owner: Elizabeth Sousa Backup Owner: Melissa Otero Approver(s): Melissa Otero Parent Document: P-008, Corrective/Preventive Action Notify of Changes: EOTA Employees Referenced Document(s): N/A F-018 Preventive Action Report Planning Worksheet 11_0414 2 of 3 Revision History: Rev. Description of Change 08_0613 Initial Release 09_0924 Worksheet modified to reflect External Audit recommendation for identification of "Cause for Potential Nonconformance". Minor editing changes. 11_0414 Added Preventive Action Number block to match Q-Pulse

223

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

7 Corrective Action Report Planning Worksheet 11_0414 1 of 3 7 Corrective Action Report Planning Worksheet 11_0414 1 of 3 EOTA - Business Form Document Title: Corrective Action Report Planning Worksheet Document Number: F-017 Rev 11_0414 Document Owner: Elizabeth Sousa Backup Owner: Melissa Otero Approver(s): Melissa Otero Parent Document: P-008, Corrective/Preventive Action Notify of Changes: EOTA Employees Referenced Document(s): N/A F-017 Corrective Action Report Planning Worksheet 11_0414 2 of 3 Revision History: Rev. Description of Change 08_0613 Initial Release 11_0414 Added problem statement to first block. F-017 Corrective Action Report Planning Worksheet 11_0414 3 of 3 Corrective Action Report Planning Worksheet Corrective Action Number: Source: Details/Problem Statement: Raised By: Raised Date: Target Date:

224

Resources required for topological quantum factoring

We consider a hypothetical topological quantum computer composed of either Ising or Fibonacci anyons. For each case, we calculate the time and number of qubits (space) necessary to execute the most computationally expensive step of Shor's algorithm, modular exponentiation. For Ising anyons, we apply Bravyi's distillation method [S. Bravyi, Phys. Rev. A 73, 042313 (2006)] which combines topological and nontopological operations to allow for universal quantum computation. With reasonable restrictions on the physical parameters we find that factoring a 128-bit number requires approximately 10{sup 3} Fibonacci anyons versus at least 3x10{sup 9} Ising anyons. Other distillation algorithms could reduce the resources for Ising anyons substantially.

Baraban, M. [Department of Physics, Yale University, 217 Prospect Street, New Haven, Connecticut 06511 (United States); Bonesteel, N. E. [Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Simon, S. H. [Rudolf Peierls Centre for Theoretical Physics, Oxford University, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

2010-06-15T23:59:59.000Z

225

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

226

Hybrid Quantum Cloning Machine

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

227

Quantum optical waveform conversion

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

228

Quantum Monte Carlo methods and lithium cluster properties

Properties of small lithium clusters with sizes ranging from n = 1 to 5 atoms were investigated using quantum Monte Carlo (QMC) methods. Cluster geometries were found from complete active space self consistent field (CASSCF) calculations. A detailed development of the QMC method leading to the variational QMC (V-QMC) and diffusion QMC (D-QMC) methods is shown. The many-body aspect of electron correlation is introduced into the QMC importance sampling electron-electron correlation functions by using density dependent parameters, and are shown to increase the amount of correlation energy obtained in V-QMC calculations. A detailed analysis of D-QMC time-step bias is made and is found to be at least linear with respect to the time-step. The D-QMC calculations determined the lithium cluster ionization potentials to be 0.1982(14) [0.1981], 0.1895(9) [0.1874(4)], 0.1530(34) [0.1599(73)], 0.1664(37) [0.1724(110)], 0.1613(43) [0.1675(110)] Hartrees for lithium clusters n = 1 through 5, respectively; in good agreement with experimental results shown in the brackets. Also, the binding energies per atom was computed to be 0.0177(8) [0.0203(12)], 0.0188(10) [0.0220(21)], 0.0247(8) [0.0310(12)], 0.0253(8) [0.0351(8)] Hartrees for lithium clusters n = 2 through 5, respectively. The lithium cluster one-electron density is shown to have charge concentrations corresponding to nonnuclear attractors. The overall shape of the electronic charge density also bears a remarkable similarity with the anisotropic harmonic oscillator model shape for the given number of valence electrons.

Owen, R.K.

1990-12-01T23:59:59.000Z

229

Integrable Quantum Computation

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

230

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

231

Physics Reports 355 (2001) 235334 Quantum phase transitions and vortex dynamics in

Contents 1. Introduction 237 1.1. Josephson-junction arrays 237 1.2. Phase-number relation 238 1.3. Structure of the review 239 2. Quantum phase transitions 240 2.1. The model of a Josephson-junction array currents 313 4.2. The quantum Hall e ect 316 4.3. Quantum computation with Josephson junctions 317

232

Colorado Natural Gas Number of Residential Consumers (Number...

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Residential Consumers (Number of Elements) Colorado Natural Gas Number of Residential Consumers (Number of Elements) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6 Year-7...

233

Colorado Natural Gas Number of Industrial Consumers (Number of...

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Industrial Consumers (Number of Elements) Colorado Natural Gas Number of Industrial Consumers (Number of Elements) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6 Year-7...

234

Colorado Natural Gas Number of Commercial Consumers (Number of...

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Commercial Consumers (Number of Elements) Colorado Natural Gas Number of Commercial Consumers (Number of Elements) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6 Year-7...

235

NAME: STUDENT NUMBER (PID): CITY, STATE ZIP: DAYTIME PHONE NUMBER

NAME: STUDENT NUMBER (PID): ADDRESS: CITY, STATE ZIP: DAYTIME PHONE NUMBER: CELL PHONE NUMBER of financial institution. 14 Cell Phone Expenses 15 Other ordinary and necessary living expenses. 16 TOTAL (add

236

Connecticut Natural Gas Number of Residential Consumers (Number...

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Residential Consumers (Number of Elements) Connecticut Natural Gas Number of Residential Consumers (Number of Elements) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6...

237

Connecticut Natural Gas Number of Commercial Consumers (Number...

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Commercial Consumers (Number of Elements) Connecticut Natural Gas Number of Commercial Consumers (Number of Elements) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6 Year-7...

238

Connecticut Natural Gas Number of Industrial Consumers (Number...

Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

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239

2-31 Review Problems 2-72 The deflection of the spring of the two-piston cylinder with a spring shown in the figure is to be determined. Analysis Summing the forces acting on the pistonN/m, the pressures in kPa (i.e., kN/m2 ) and the diameters in m units. 2-73 The pressure in chamber 1 of the two-piston

Bahrami, Majid

240

A Graphic Representation of States for Quantum Copying Machines

The aim of this paper is to introduce a new graphic representation of quantum states by means of a specific application: the analysis of two models of quantum copying machines. The graphic representation by diagrams of states offers a clear and detailed visualization of quantum information's flow during the unitary evolution of not too complex systems. The diagrams of states are exponentially more complex in respect to the standard representation and this clearly illustrates the discrepancy of computational power between quantum and classical systems. After a brief introductive exposure of the general theory, we present a constructive procedure to illustrate the new representation by means of concrete examples. Elementary diagrams of states for single-qubit and two-qubit systems and a simple scheme to represent entangled states are presented. Quantum copying machines as imperfect cloners of quantum states are introduced and the quantum copying machines of Griffiths and Niu and of Buzek and Hillery are analyzed, determining quantum circuits of easier interpretation. The method has indeed shown itself to be extremely successful for the representation of the involved quantum operations and it has allowed to point out the characteristic aspects of the quantum computations examined.

Sara Felloni; Giuliano Strini

2006-09-29T23:59:59.000Z

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they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

241

A New Ontological View of the Quantum Measurement Problem

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

242

A quantum gravitational origin of dark energy

We propose a new explanation of the origin of the small vacuum energy of the present universe within a nonperturbative quantum theory of gravity with torsional instantons. These pseudoparticles, which were recently found to exist in a first order formulation of Giddings-Strominger axionic gravity, carry nontrivial Nieh-Yan topological charge. The nonperturbative vacuum as generated due to tunneling effects and parametrised by the Barbero-Immirzi topological angle is shown to be stable under quantum fluctuations. In this theory, absence of any observable parity violating effect fixes the Barbero-Immirzi parameter to a small value, which is determined by the current estimate of the Hubble constant.

Sengupta, Sandipan

2015-01-01T23:59:59.000Z

243

Local models and EPR quantum correlations

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

244

Practical Characterization of Quantum Devices without Tomography

Science Journals Connector (OSTI)

Quantum tomography is the main method used to assess the quality of quantum information processing devices. However, the amount of resources needed for quantum tomography is exponential in the device size. Part of the problem is that tomography generates much more information than is usually sought. Taking a more targeted approach, we develop schemes that enable (i) estimating the fidelity of an experiment to a theoretical ideal description, (ii) learning which description within a reduced subset best matches the experimental data. Both these approaches yield a significant reduction in resources compared to tomography. In particular, we demonstrate that fidelity can be estimated from a number of simple experiments that is independent of the system size, removing an important roadblock for the experimental study of larger quantum information processing units.

Marcus P. da Silva; Olivier Landon-Cardinal; David Poulin

2011-11-16T23:59:59.000Z

245

Time-Energy Costs of Quantum Measurements

Time and energy of quantum processes are a tradeoff against each other. We propose to ascribe to any given quantum process a time-energy cost to quantify how much computation it performs. Here, we analyze the time-energy costs for general quantum measurements, along a similar line as our previous work for quantum channels, and prove exact and lower bound formulae for the costs. We use these formulae to evaluate the efficiencies of actual measurement implementations. We find that one implementation for a Bell measurement is optimal in time-energy. We also analyze the time-energy cost for unambiguous state discrimination and find evidence that only a finite time-energy cost is needed to distinguish any number of states.

Chi-Hang Fred Fung; H. F. Chau

2014-02-20T23:59:59.000Z

246

Quantum limits to estimation of photon deformation

We address potential deviations of radiation field from the bosonic behaviour and employ local quantum estimation theory to evaluate the ultimate bounds to precision in the estimation of these deviations using quantum-limited measurements on optical signals. We consider different classes of boson deformation and found that intensity measurement on coherent or thermal states would be suitable for their detection making, at least in principle, tests of boson deformation feasible with current quantum optical technology. On the other hand, we found that the quantum signal-to-noise ratio (QSNR) is vanishing with the deformation itself for all the considered classes of deformations and probe signals, thus making any estimation procedure of photon deformation inherently inefficient. A partial way out is provided by the polynomial dependence of the QSNR on the average number of photon, which suggests that, in principle, it would be possible to detect deformation by intensity measurements on high-energy thermal states.

Giovanni De Cillis; Matteo G. A. Paris

2014-07-08T23:59:59.000Z

247

Time-energy costs of quantum measurements

Science Journals Connector (OSTI)

Time and energy of quantum processes are a tradeoff against each other. We propose to ascribe to any given quantum process a time-energy cost to quantify how much computation it performs. Here, we analyze the time-energy costs for general quantum measurements, along a similar line as our previous work for quantum channels, and prove exact and lower bound formulas for the costs. We use these formulas to evaluate the efficiencies of actual measurement implementations. We find that one implementation for a Bell measurement is optimal in time energy. We also analyze the time-energy cost for unambiguous state discrimination and find evidence that only a finite time-energy cost is needed to distinguish any number of states.

Chi-Hang Fred Fung and H. F. Chau

2014-05-08T23:59:59.000Z

248

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; Raúl García-Patrón; Nicolas J. Cerf; Timothy C. Ralph; Jeffrey H. Shapiro; Seth Lloyd

2012-05-01T23:59:59.000Z

249

Nonlinear Phenomenology from Quantum Mechanics: Soliton in a Lattice

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

250

The quantization of topology, from quantum Hall effect to quantum gravity

It is the goal of this article to extend the notion of quantization from the standard interpretation focused on non-commuting observables defined starting from classical analogues, to the topological equivalents defined in terms of coefficient groups in (co)homology. It is shown that the commutation relations between quantum observables become (non)compatibility relations between coefficient groups. The main result is the construction of a new, higher-level form of quantization, as seen from the perspective of the universal coefficient theorem. This idea brings us closer to a consistent quantization of gravity, allows for a systematic description of topology changing string interactions but also gives new, quantum-topological degrees of freedom in discussions involving quantum information. On the practical side, a possible connection to the fractional quantum Hall effect is explored.

Andrei T. Patrascu

2014-11-17T23:59:59.000Z

251

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

North Execution - (2009 - 2011) North Execution - (2009 - 2011) Construction Project Number 2009 2010 2011 Project Description ANMLPL 0001C 76,675.32 - - Animas-Laplata circuit breaker and power rights CRGRFL 0001C - - 7,177.09 Craig Rifle Bay and transfer bay upgrade to 2000 amps; / Convert CRG RFL to 345 kV out of Bears Ear Sub FGE 0019C - - 39,207.86 Replace 69/25kV transformer KX2A at Flaming Gorge FGE 0020C - - 52,097.12 Flaming Gorge: Replace failed KW2A transformer HDN 0069C 16,638.52 208,893.46 3,704,578.33 Replace failed transformer with KZ1A 250 MVA 230/138kv

252

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

supports CMM-SW Level 2 supports CMM-SW Level 2 Mapping of the DOE Systems Engineering Methodology to the Software Engineering Institute (SEI) Software Capability Maturity Model (CMM- SW) level 2. Date: September 2002 Page 1 KPA Activity Number KPA Activity SEM Section SME Work Product SQSE Web Site http://cio.doe.gov/sqse REQUIREMENTS MANAGEMENT RM-1 The software engineering group reviews the allocated requirements before they are incorporated in the software project. Chapter 3.0 * Develop High-Level Project Requirements Chapter 4.0 * Establish Functional Baseline * Project Plan * Requirements Specification Document * Requirements Management awareness * Defining Project Requirements RM-2 The software engineering group uses the allocated requirements as the basis for

253

Recycling of quantum information: Multiple observations of quantum systems

Given a finite number of copies of an unknown qubit state that have already been measured optimally, can one still extract any information about the original unknown state? We give a positive answer to this question and quantify the information obtainable by a given observer as a function of the number of copies in the ensemble, and of the number of independent observers that, one after the other, have independently measured the same ensemble of qubits before him. The optimality of the protocol is proven and extensions to other states and encodings are also studied. According to the general lore, the state after a measurement has no information about the state before the measurement. Our results manifestly show that this statement has to be taken with a grain of salt, specially in situations where the quantum states encode confidential information.

Peter Rapcan; John Calsamiglia; Ramon Munoz-Tapia; Emilio Bagan; Vladimir Buzek

2007-08-08T23:59:59.000Z

254

Magic State Distillation and Gate Compilation in Quantum Algorithms for Quantum Chemistry

Quantum algorithms for quantum chemistry map the dynamics of electrons in a molecule to the dynamics of a coupled spin system. To reach chemical accuracy for interesting molecules, a large number of quantum gates must be applied which implies the need for quantum error correction and fault-tolerant quantum computation. Arbitrary fault-tolerant operations can be constructed from a small, universal set of fault-tolerant operations by gate compilation. Quantum chemistry algorithms are compiled by decomposing the dynamics of the coupled spin-system using a Trotter formula, synthesizing the decomposed dynamics using Clifford operations and single-qubit rotations, and finally approximating the single-qubit rotations by a sequence of fault-tolerant single-qubit gates. Certain fault-tolerant gates rely on the preparation of specific single-qubit states referred to as magic states. As a result, gate compilation and magic state distillation are critical for solving quantum chemistry problems on a quantum computer. We review recent progress that has improved the efficiency of gate compilation and magic state distillation by orders of magnitude.

Colin J. Trout; Kenneth R. Brown

2015-01-07T23:59:59.000Z

255

Science Journals Connector (OSTI)

We present a microscopic theory of the magnetic field dependence of the optical properties of II–VI semiconductor quantum dots containing a single magnetic (Mn) impurity. The single-particle electron and heavy-hole states are described exactly by two-dimensional harmonic oscillators in a magnetic field, the Mn ion is treated as a spin of an isoelectronic impurity, and the quantum dot anisotropy is included perturbatively. The electron-hole direct, short-, and long-range exchange electron-hole Coulomb interactions, as well as the short-range spin-spin contact exchange interaction of the electron and the hole with the magnetic impurity is included. The electron-hole-Mn states are expanded in a finite number of configurations controlled by the number of confined electronic quantum dot shells and the full interacting Hamiltonian is diagonalized numerically in this basis. The absorption and emission spectrum is predicted as a function of photon energy, magnetic field, number of confined shells, and anisotropy. It is shown that the magnetic-field-induced enhancement of the exchange interaction of the Mn spin with the exciton is largely canceled by increased electron-hole Coulomb interactions. The predicted weak magnetic field dependence of the spacing of emission lines agrees well with the results of the spin model at low magnetic fields but differs at higher magnetic fields. Correlations in the exciton-Mn complex are predicted to determine absorption spectra.

Anna H. Trojnar; Marek Korkusi?ski; Marek Potemski; Pawel Hawrylak

2012-04-06T23:59:59.000Z

256

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.

Damián Pitalúa-García

2013-05-22T23:59:59.000Z

257

Feasible quantum engineering of quantum multiphoton superpositions

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

258

Photovoltaic Cell Quantum Efficiency Basics | Department of Energy

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

Cell Quantum Efficiency Basics Cell Quantum Efficiency Basics Photovoltaic Cell Quantum Efficiency Basics August 20, 2013 - 3:05pm Addthis Quantum efficiency (QE) is the ratio of the number of charge carriers collected by a photovoltaic (PV) cell to the number of photons-or packets of light-of a given energy shining on the solar cell. Quantum efficiency therefore relates to the response of a solar cell to the various wavelengths in the spectrum of light shining on the cell. The QE is given as a function of either wavelength or energy. If all the photons of a certain wavelength are absorbed and the resulting minority carriers (for example, electrons in a p-type material) are collected, then the QE at that particular wavelength has a value of one. The QE for photons with energy below the bandgap is zero.

259

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

Science Journals Connector (OSTI)

Ballistic transport through a three-dimensional–one-dimensional–three-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

260

Spectrum of electron-hole states of the Si/Ge structure with Ge quantum dots

The lateral photoconductivity spectra of Si/Ge multilayer structures with Ge quantum dots of various sizes are investigated. We observed optical transition lines between the hole levels of quantum dots and electronic states of Si. This enabled us to construct a detailed energy level diagram of the electron-hole spectrum of the Si/Ge structures. It is shown that the hole levels of Ge quantum dots are successfully described by the 'quantum box' model using the actual sizes of Ge islands. It I found that the position of the longwavelength photosensitivity boundary of Si/Ge structures with Ge quantum dots can be controlled by changing the growth parameters.

Talochkin, A. B., E-mail: tal@thermo.isp.nsc.ru; Chistokhin, I. B., E-mail: igor@thermo.isp.nsc.ru [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-09-15T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

261

Photoconductivity of Si/Ge multilayer structures with Ge quantum dots pseudomorphic to the Si matrix

Longitudinal photoconductivity spectra of Si/Ge multilayer structures with Ge quantum dots grown pseudomorphically to the Si matrix are studied. Lines of optical transitions between hole levels of quantum dots and Si electronic states are observed. This allowed us to construct a detailed energy-level diagram of electron-hole levels of the structure. It is shown that hole levels of pseudomorphic Ge quantum dots are well described by the simplest 'quantum box' model using actual sizes of Ge islands. The possibility of controlling the position of the long-wavelength photosensitivity edge by varying the growth parameters of Si/Ge structures with Ge quantum dots is determined.

Talochkin, A. B., E-mail: tal@thermo.isp.nsc.ru; Chistokhin, I. B. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-07-15T23:59:59.000Z

262

Quantum spins mimic refrigerator magnets - Argonne National Laboratories,

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

Highlights > Quantum spins mimic refrigerator Highlights > Quantum spins mimic refrigerator magnets Quantum spins mimic refrigerator magnets By Joseph Bernstein * October 11, 2012 The behavior of magnetic moments in metal oxides such as layered iridium is dominated by strong spin-orbit coupling effects. In layered compounds such as Sr3Ir2O7 (shown on the left), the direction of these moments (blue arrows) is controlled at the quantum level by dipolar interactions that are akin to those of classical bar magnets. Another outcome is an unprecedented 'magnon gap' (shown at right), which was measured at the Argonne Advanced Photon Source and reveals that these underlying dipolar magnetic interactions are extremely strong. Current electronic devices depend on manipulating charge. Alternative approaches may rely on not only charge but also the spin of electrons.

263

Satellite-Based Quantum Communications

Single-photon quantum communications (QC) offers the attractive feature of 'future proof', forward security rooted in the laws of quantum physics. Ground based quantum key distribution (QKD) experiments in optical fiber have attained transmission ranges in excess of 200km, but for larger distances we proposed a methodology for satellite-based QC. Over the past decade we have devised solutions to the technical challenges to satellite-to-ground QC, and we now have a clear concept for how space-based QC could be performed and potentially utilized within a trusted QKD network architecture. Functioning as a trusted QKD node, a QC satellite ('QC-sat') could deliver secret keys to the key stores of ground-based trusted QKD network nodes, to each of which multiple users are connected by optical fiber or free-space QC. A QC-sat could thereby extend quantum-secured connectivity to geographically disjoint domains, separated by continental or inter-continental distances. In this paper we describe our system concept that makes QC feasible with low-earth orbit (LEO) QC-sats (200-km-2,000-km altitude orbits), and the results of link modeling of expected performance. Using the architecture that we have developed, LEO satellite-to-ground QKD will be feasible with secret bit yields of several hundred 256-bit AES keys per contact. With multiple ground sites separated by {approx} 100km, mitigation of cloudiness over any single ground site would be possible, potentially allowing multiple contact opportunities each day. The essential next step is an experimental QC-sat. A number of LEO-platforms would be suitable, ranging from a dedicated, three-axis stabilized small satellite, to a secondary experiment on an imaging satellite. to the ISS. With one or more QC-sats, low-latency quantum-secured communications could then be provided to ground-based users on a global scale. Air-to-ground QC would also be possible.

Hughes, Richard J [Los Alamos National Laboratory; Nordholt, Jane E [Los Alamos National Laboratory; McCabe, Kevin P [Los Alamos National Laboratory; Newell, Raymond T [Los Alamos National Laboratory; Peterson, Charles G [Los Alamos National Laboratory

2010-09-20T23:59:59.000Z

264

Efficient distributed quantum computing

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

265

Systematic quantum corrections to screening in thermonuclear fusion

We develop a series expansion of the plasma screening length away from the classical limit in powers of $\\hbar^{2}$. It is shown that the leading order quantum correction increases the screening length in solar conditions by approximately 2% while it decreases the fusion rate by approximately $ 0.34%$. We also calculate the next higher order quantum correction which turns out to be approximately 0.05%.

Chitanvis, S M

2006-01-01T23:59:59.000Z

266

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

267

Systematic quantum corrections to screening in thermonuclear fusion

We develop a series expansion of the plasma screening length away from the classical limit in powers of $\\hbar^{2}$. It is shown that the leading order quantum correction increases the screening length in solar conditions by approximately 2% while it decreases the fusion rate by approximately $ 0.34%$. We also calculate the next higher order quantum correction which turns out to be approximately 0.05%.

Shirish M. Chitanvis

2006-06-13T23:59:59.000Z

268

On neutron numbers and atomic masses

Science Journals Connector (OSTI)

On neutron numbers and atomic masses ... Assigning neutron numbers, correct neutron numbers, and atomic masses and nucleon numbers. ...

R. Heyrovská

1992-01-01T23:59:59.000Z

269

Black holes as self-sustained quantum states, and Hawking radiation

We employ the recently proposed formalism of the "horizon wave-function" to investigate the emergence of a horizon in models of black holes as Bose-Einstein condensates of gravitons. We start from the Klein-Gordon equation for a massless scalar (toy graviton) field coupled to a static matter current. The (spherically symmetric) classical field reproduces the Newtonian potential generated by the matter source, and the corresponding quantum state is given by a coherent superposition of scalar modes with continuous occupation number. Assuming an attractive self-interaction that allows for bound states, one finds that (approximately) only one mode is allowed, and the system can be confined in a region of the size of the Schwarzschild radius. This radius is then shown to correspond to a proper horizon, by means of the horizon wave-function of the quantum system, with an uncertainty in size naturally related to the expected typical energy of Hawking modes. In particular, this uncertainty decreases for larger black hole mass (with larger number of light scalar quanta), in agreement with semiclassical expectations, a result which does not hold for a single very massive particle. We finally speculate that a phase transition should occur during the gravitational collapse of a star, ideally represented by a static matter current and Newtonian potential, that leads to a black hole, again ideally represented by the condensate of toy gravitons, and suggest an effective order parameter that could be used to investigate this transition.

Roberto Casadio; Andrea Giugno; Octavian Micu; Alessio Orlandi

2014-10-06T23:59:59.000Z

270

Electron exchange-correlation in quantum mechanics

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

271

Changing quantum reference frames

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

272

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

273

Nonequilibrium quantum kinetics

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

274

Impossibility of secure cloud quantum computing for classical client

The first generation quantum computer will be implemented in the cloud style, since only few groups will be able to access such an expensive and high-maintenance machine. How the privacy of the client can be protected in such a cloud quantum computing? It was theoretically shown [A. Broadbent, J. F. Fitzsimons, and E. Kashefi, Proceedings of the 50th Annual IEEE Symposium on Foundation of Computer Science, 517 (2009)], and experimentally demonstrated [S. Barz, E. Kashefi, A. Broadbent, J. F. Fitzsimons, A. Zeilinger, and P. Walther, Science {\\bf335}, 303 (2012)] that a client who can generate randomly-rotated single qubit states can delegate her quantum computing to a remote quantum server without leaking any privacy. The generation of a single qubit state is not too much burden for the client, and therefore we can say that "almost classical client" can enjoy the secure cloud quantum computing. However, isn't is possible to realize a secure cloud quantum computing for a client who is completely free from any quantum technology? Here we show that perfectly-secure cloud quantum computing is impossible for a completely classical client unless classical computing can simulate quantum computing, or a breakthrough is brought in classical cryptography.

Tomoyuki Morimae; Takeshi Koshiba

2014-07-07T23:59:59.000Z

275

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

276

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

277

Topological Quantum Distillation

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

278

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

279

Quantum theory of nonequilibrium processes II. Application to nuclear collisions

In the high-energy (E/sub lab/> or =200 MeV/nucl) heavy ion-collisions, the quantum uncertainty of nucleon energies, given by the collision frequency, is of the order of (50-100) MeV. At hundreds MeV/nucl beam energies, the uncertainty is comparable with nucleon energies in the equal ion-velocity frame, indicating a quantum character of the dynamics. The quantum dynamics of a collision process is examined using nonequilibrium Green's function methods. Numerical calculations of collisions in an interpenetrating nuclear matter model, at the energy E/sub lab/ = 400 MeV/nucl, are performed. Comparison of the quantum dynamics, with the classical Markovian dynamics from the Boltzmann equation, reveals effects of the ill-defined nucleon energies in the nucleon momentum distribution. It is shown that the quantum dynamics proceeds twice as slow as Boltzmann dynamics, but the off-shell kinematics compensates for this somewhat.

Danielewicz, P.

1984-02-01T23:59:59.000Z

280

Quantum Markovian activated surface diffusion of interacting adsorbates

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

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

281

Spatially dependent decoherence and anomalous diffussion of quantum walks

We analyze the long time behavior of a discrete time quantum walk subject to decoherence with a strong spatial dependence, acting on one half of the lattice. We show that, except for limiting cases on the decoherence parameter, the quantum walk at late times behaves sub-ballistically, meaning that the characteristic features of the quantum walk are not completely spoiled. Contrarily to expectations, the asymptotic behavior is non Markovian, and depends on the amount of decoherence. This feature can be clearly shown on the long time value of the Generalized Chiral Distribution (GCD).

A. Perez; A. Romanelli

2012-03-30T23:59:59.000Z

282

Hidden Variables and Quantum Statistics Nature

It is shown that the nature of quantum statistics can be clarified by assuming the existence of a background of random gravitational fields and waves, distributed isotropically in the space. This background is responsible for correlating phases of oscillations of identical microobjects. If such a background of random gravitational fields and waves is considered as hidden variables then taking it into account leads to the Bell-type inequalities that are fairly consistent with the experimental data.

T. F. Kamalov

2007-03-14T23:59:59.000Z

283

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

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

284

Optimized multiparty quantum clock synchronization

A multiparty protocol for distributed quantum clock synchronization has been claimed to provide universal limits on the clock accuracy, viz., that accuracy monotonically decreases with the number n of party members. But this is only true for synchronization when one limits oneself to W states. This work shows that the usage of Z (Symmetric Dicke) states, a generalization of W states, results in improved accuracy, having a maximum when Left-Floor n/2 Right-Floor of its members have their qubits with a |1> eigenstate.

Ben-Av, Radel; Exman, Iaakov [Software Engineering Department, Jerusalem College of Engineering, POB 3566, Jerusalem, 91035 (Israel)

2011-07-15T23:59:59.000Z

285

Quantum Physics and Nanotechnology

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

286

8 Characterization of Quantum Devices Giacomo Mauro D'Ariano and Paoloplacido Lo Presti

8 Characterization of Quantum Devices Giacomo Mauro D'Ariano and Paoloplacido Lo Presti QUIT Group-Verlag Berlin Heidelberg 2004 #12;298 Giacomo Mauro D'Ariano and Paoloplacido Lo Presti it was shown

D'Ariano, Giacomo Mauro

287

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

288

Exchange-induced splitting of exciton energy levels in quantum wires

Science Journals Connector (OSTI)

Effects of the electron-hole exchange interaction on excitons in one-dimensional quantum wires are studied theoretically by performing a simplified calculation with a scaling argument. It is shown that the exchange parameters are drastically enhanced in narrow quantum wires compared to the bulk values. As expected, the variation of the exchange-induced splitting as a function of the wire size has the same qualitative behavior as those in comparable two-dimensional quantum wells but with much higher magnitudes.

Y. Chen

1990-05-15T23:59:59.000Z

289

On the Interpretation of Energy as the Rate of Quantum Computation

Science Journals Connector (OSTI)

Over the last few decades, developments in the physical limits of computing and quantum computing have increasingly taught us that it can be helpful to think about physics itself in computational terms. For example, work over the last decade has shown ... Keywords: 03.65 Ta, 03.67, Hamiltonian energy, Margolus---Levitin theorem, Time evolution operator, action of the Hamiltonian operator, energy as computing, geometric phase, physics as computation, quantum computational complexity, quantum logic gates

Michael P. Frank

2005-10-01T23:59:59.000Z

290

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

291

Adiabatic topological quantum computing

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

292

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

293

Efficient photon number detection with silicon avalanche photodiodes

We demonstrate an efficient photon number detector for visible wavelengths using a silicon avalanche photodiode. Under subnanosecond gating, the device is able to resolve up to four photons in an incident optical pulse. The detection efficiency at 600 nm is measured to be 73.8%, corresponding to an avalanche probability of 91.1% of the absorbed photons, with a dark count probability below 1.1x10^{-6} per gate. With this performance and operation close to room temperature, fast-gated silicon avalanche photodiodes are ideal for optical quantum information processing that requires single-shot photon number detection.

O. Thomas; Z. L. Yuan; J. F. Dynes; A. W. Sharpe; A. J. Shields

2010-07-21T23:59:59.000Z

294

Magnetic field control of the intraband optical absorption in two-dimensional quantum rings

Linear and nonlinear optical absorption coefficients of the two-dimensional semiconductor ring in the perpendicular magnetic field B are calculated within independent electron approximation. Characteristic feature of the energy spectrum are crossings of the levels with adjacent nonpositive magnetic quantum numbers as the intensity B changes. It is shown that the absorption coefficient of the associated optical transition is drastically decreased at the fields corresponding to the crossing. Proposed model of the Volcano disc allows to get simple mathematical analytical results, which provide clear physical interpretation. An interplay between positive linear and intensity-dependent negative cubic absorption coefficients is discussed; in particular, critical light intensity at which additional resonances appear in the total absorption dependence on the light frequency is calculated as a function of the magnetic field and levels' broadening.

Olendski, O., E-mail: oolendski@ksu.edu.sa [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2454, Riyadh 11451 (Saudi Arabia); Barakat, T., E-mail: tbarakat@ksu.edu.sa [Department of Physics, King Saud University, P.O. Box 2454, Riyadh 11451 (Saudi Arabia)

2014-02-28T23:59:59.000Z

295

Quantum Illumination at the Microwave Wavelengths

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy.

Shabir Barzanjeh; Saikat Guha; Christian Weedbrook; David Vitali; Jeffrey H. Shapiro; Stefano Pirandola

2015-01-31T23:59:59.000Z

296

Nano-wires with surface disorder: Giant localization lengths and quantum-to-classical crossover

We investigate electronic quantum transport through nano-wires with one-sided surface roughness. A magnetic field perpendicular to the scattering region is shown to lead to exponentially diverging localization lengths in the quantum-to-classical crossover regime. This effect can be quantitatively accounted for by tunneling between the regular and the chaotic components of the underlying mixed classical phase space.

J. Feist; A. Bäcker; R. Ketzmerick; S. Rotter; B. Huckestein; J. Burgdörfer

2006-09-14T23:59:59.000Z

297

Photonic quantum walk in a single beam with twisted light

Inspired by the classical phenomenon of random walk, the concept of quantum walk has emerged recently as a powerful platform for the dynamical simulation of complex quantum systems, entanglement production and universal quantum computation. Such a wide perspective motivates a renewing search for efficient, scalable and stable implementations of this quantum process. Photonic approaches have hitherto mainly focused on multi-path schemes, requiring interferometric stability and a number of optical elements that scales quadratically with the number of steps. Here we report the experimental realization of a quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous indistinguishable photons. The whole process develops in a single light beam, with no need of interferometers, and requires optical resources scaling linearly with the number of steps. Our demonstration introduces a novel versatile photonic platform for implementing quantum simulations, based on exploiting the transverse modes of a single light beam as quantum degrees of freedom.

Filippo Cardano; Francesco Massa; Ebrahim Karimi; Sergei Slussarenko; Domenico Paparo; Corrado de Lisio; Fabio Sciarrino; Enrico Santamato; Lorenzo Marrucci

2014-03-19T23:59:59.000Z

298

Quantum Thermodynamic Cycles and Quantum Heat Engines (II)

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

299

Quantum Geometry and Black Holes

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

300

Economical standard quantum process tomography

Recently, Bendersky \\emph{et al.} developed a method to complete the task of characterizing an arbitrary $\\chi$ matrix element in a scalable way, Phys. Rev. Lett. Vol. \\textbf{100}, 190403(2008), where an auxiliary system was needed. In present work, we shall show that the same task can also be completed within the scheme of standard quantum process tomography (SQPT) where there is no requirement for ancilla. Our method depends on two observations: With the elaborately chosen operators basis, the SQPT may have an economical form where a single run of experiment, in which we measure the expectation value of a chosen operator in the outport of the quantum channel with a known input, is sufficient to characterize a selected $\\chi$ matrix element; With the progress recently achieved in quantum entanglement detection, we also find that the number of the experimental settings to realize the experiment for the selected $\\chi$ matrix element does not exceed 2N for the N-qubits system. For practice, our scheme can be applied for the cases where the controlled two-body interaction is neither available nor desirable.

Xiaohua Wu; Ke Xu

2010-11-30T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

301

Transcendental L2 -Betti numbers

Transcendental L2 -Betti numbers Atiyah's question Thomas Schick GÂ¨ottingen OA Chennai 2010 Thomas Schick (GÂ¨ottingen) Transcendental L2 -Betti numbers Atiyah's question OA Chennai 2010 1 / 24 #12 = ~M/) with fundamental domain F. L2-Betti numbers:= normalized dimension( space of L2-harmonic forms

Sunder, V S

302

Data Compression with Prime Numbers

A compression algorithm is presented that uses the set of prime numbers. Sequences of numbers are correlated with the prime numbers, and labeled with the integers. The algorithm can be iterated on data sets, generating factors of doubles on the compression.

Gordon Chalmers

2005-11-16T23:59:59.000Z

303

Hybrid Quantum Computation in Quantum Optics

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

304

Nucleon semimagic numbers and low-energy neutron scattering

It is shown that experimental values of the cross sections of inelastic low-energy neutron scattering on even-even nuclei together with the description of these cross sections in the framework of the coupled channel optical model may be considered as a reliable method for finding nuclei with a semimagic number (or numbers) of nucleons. Some examples of the application of this method are considered.

D. A. Zaikin; I. V. Surkova

2010-04-09T23:59:59.000Z

305

I will argue that the proposal of establishing operational foundations of Quantum Theory should have top-priority, and that the Lucien Hardy's program on Quantum Gravity should be paralleled by an analogous program on Quantum Field Theory (QFT), which needs to be reformulated, notwithstanding its experimental success. In this paper, after reviewing recently suggested operational 'principles of the quantumness', I address the problem on whether Quantum Theory and Special Relativity are unrelated theories, or instead, if the one implies the other. I show how Special Relativity can be indeed derived from causality of Quantum Theory, within the computational paradigm 'the universe is a huge quantum computer', reformulating QFT as a Quantum-Computational Field Theory (QCFT). In QCFT Special Relativity emerges from the fabric of the computational network, which also naturally embeds gauge invariance. In this scheme even the quantization rule and the Planck constant can in principle be derived as emergent from the underlying causal tapestry of space-time. In this way Quantum Theory remains the only theory operating the huge computer of the universe.Is the computational paradigm only a speculative tautology (theory as simulation of reality), or does it have a scientific value? The answer will come from Occam's razor, depending on the mathematical simplicity of QCFT. Here I will just start scratching the surface of QCFT, analyzing simple field theories, including Dirac's. The number of problems and unmotivated recipes that plague QFT strongly motivates us to undertake the QCFT project, since QCFT makes all such problems manifest, and forces a re-foundation of QFT.

D'Ariano, Giacomo Mauro [QUIT Group, Dipartimento di Fisica 'A. Volta', 27100 Pavia (Italy) and Center for Photonic Communication and Computing, Northwestern University, Evanston, IL 60208 (Italy)

2010-05-04T23:59:59.000Z

306

Onset of a Quantum Phase Transition with a Trapped Ion Quantum Simulator

A quantum simulator is a well controlled quantum system that can simulate the behavior of another quantum system which may require exponentially large classical computing resources to understand otherwise. In the 1980s, Feynman proposed the use of quantum logic gates on a standard controllable quantum system to efficiently simulate the behavior of a model Hamiltonian. Recent experiments using trapped ions and neutral atoms have realized quantum simulation of Ising model in presence of external magnetic fields, and showed almost arbitrary control in generating non-trivial Ising coupling patterns. Here we use laser-cooled trapped 171-Yb+ ions to simulate the emergence of magnetism in a system of interacting spins by implementing a fully-connected non-uniform ferromagnetic Ising model in a transverse magnetic field. To link this quantum simulation to condensed matter physics, we measure scalable correlation functions and order parameters appropriate for the description of larger systems, such as various moments of the magnetization. By increasing the Ising coupling strengths compared with the external field, the crossover from paramagnetism to ferromagnetic order sharpens as the system is scaled up from N = 2 to 9 trapped ion spins. This points toward the onset of a quantum phase transition that should become infinitely sharp as the system approaches the macroscopic scale. We compare the measured ground state order to theory, which may become intractable for non-uniform Ising couplings as the number of spins grows beyond 20- 30 and even NP complete for a fully-connected frustrated Ising model, making this experiment an important benchmark for large-scale quantum simulation.

R. Islam; E. E. Edwards; K. Kim; S. Korenblit; C. Noh; H. Carmichael; G. -D. Lin; L. -M. Duan; C. -C. Joseph Wang; J. K. Freericks; C. Monroe

2011-03-12T23:59:59.000Z

307

Quantum Copy-Protection and Quantum Money

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

308

Generalized quantum defect methods in quantum chemistry

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

309

Nested Quantum Walks with Quantum Data Structures

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

310

Properties of Reactive Oxygen Species by Quantum Monte Carlo

The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of Chemistry, Biology and Atmospheric Science. Nevertheless, the electronic structure of such species is a challenge for ab-initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as $N^3-N^4$, where $N$ is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

Andrea Zen; Bernhardt L. Trout; Leonardo Guidoni

2014-03-11T23:59:59.000Z

311

Quantum Copy-Protection and Quantum Money

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

312

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

313

Quantum cryptographic system with reduced data loss

A secure method for distributing a random cryptographic key with reduced data loss. Traditional quantum key distribution systems employ similar probabilities for the different communication modes and thus reject at least half of the transmitted data. The invention substantially reduces the amount of discarded data (those that are encoded and decoded in different communication modes e.g. using different operators) in quantum key distribution without compromising security by using significantly different probabilities for the different communication modes. Data is separated into various sets according to the actual operators used in the encoding and decoding process and the error rate for each set is determined individually. The invention increases the key distribution rate of the BB84 key distribution scheme proposed by Bennett and Brassard in 1984. Using the invention, the key distribution rate increases with the number of quantum signals transmitted and can be doubled asymptotically.

Lo, Hoi-Kwong (1309, Low Block, Lei Moon House Ap Lei Chau Estate, Hong Kong, HK); Chau, Hoi Fung (Flat C, 42nd Floor, Tower 1, University Heights 23 Pokfield Road, Pokfulam, Hong Kong, HK)

1998-01-01T23:59:59.000Z

314

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 dipole–electric charge system leads to an infinite number of different quantization conditions and an apparent incompatibility between quantum mechanics and the dipole–charge 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 dipole–charge field angular momentum and the nucleon spin crisis is given.

D. Singleton

1998-01-01T23:59:59.000Z

315

wavelength conversion. The InP-InGaAsP offset quantum-well shallow- ridge technology platform has been shown been thinned, and individual bars SGDBRSOA EAM PINSOA Receiver RLoad Transmitter in out InP/InGaAsP to 10 GHz. Index Terms-- Electro-absorption modulators (EAMs), offset quantum well, sampled grating

Coldren, Larry A.

316

The authors report on high quality InGaAsP/InP multiple quantum well structures grown by chemical beam epitaxy with absorption at the 1.3 to 1.5{micro}m range. Transmission profiles with remarkable excitonic features and sharply defined absorption edges for p-i-n samples with as many as 200 periods are shown to be achievable. Very sharp satellite peaks with linewidth comparable with that from the substrate are shown in the x-ray diffraction. The authors use a new method to monitor the substrate temperature which shows excellent results in terms of homogeneity of layer thickness and composition even for structures with a large number periods.

Mendonca, C.A.C. [Univ. Estadual de Campinas-IFGW-DFA-LPD, Sao Paulo (Brazil); Chiu, T.H. [AT and T Bell Labs., Holmdel, NJ (United States)

1996-12-31T23:59:59.000Z

317

Quantum Copy-Protection and Quantum Money

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

318

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

319

Quantum like modelling of the non-separability of voters' preferences in the U.S. political system

Divided Government is nowadays a common feature of the U.S. political system. The voters can cast partisan ballots for two political powers the executive (Presidential elections) and the legislative (the Congress election). Some recent studies have shown that many voters tend to shape their preferences for the political parties by choosing different parties in these two election contests. This type of behavior referred to by Smith et al. (1999) as "ticket splitting" shows irrationality of behavior (such as preference reversal) from the perspective of traditional decision making theories (Von Neumann and Morgenstern (1953), Savage, (1954)). It has been shown by i.e. Zorn and Smith (2011) and also Khrennikova et al. (2014) that these types of "non-separable" preferences are context dependent and can be well accommodated in a quantum like framework. In this paper we use data from Smith et al. (1999) to show first of all probabilistic violation of classical (Kolmogorovian) framework. We proceed with the depiction of our observables (the Congress and the Presidential contexts) with the aid of the quantum probability formula that incorporates the "contextuality" of the decision making process through the interference term. Statistical data induces an interference term of large magnitude a so called hyperbolic interference. We perform with help of our transition probabilities a state reconstruction of the voters state vectors to test for the applicability of the generalized Born rule. This state can be mathematically represented in the generalized Hilbert space based on hyper-complex numbers.

Polina Khrennikova

2014-05-07T23:59:59.000Z

320

The security of a cryptographic key that is generated by communication through a noisy quantum channel relies on the ability to distill a shorter secure key sequence from a longer insecure one. We show that - for protocols that use quantum channels of any dimension and completely characterize them by state tomography - the noise threshold for classical advantage distillation of a specific kind is substantially lower than the threshold for quantum entanglement distillation if the eavesdropper can perform powerful coherent attacks. In marked contrast, earlier investigations had shown that the thresholds are identical for incoherent attacks on the same classical distillation scheme. It remains an open question whether other schemes for classical advantage distillation have higher thresholds for coherent eavesdropping attacks.

Kaszlikowski, Dagomir; Lim, J.Y.; Englert, Berthold-Georg [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Kwek, L.C. [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); National Institute of Education, Nanyang Technological University, Singapore 639798 (Singapore)

2005-10-15T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

321

Unsteady aerodynamic models for agile flight at low Reynolds numbers

Unsteady aerodynamic models for agile flight at low Reynolds numbers Steven L. Brunton , Clarence W for the unsteady aerodynamic forces on a small wing in response to agile maneuvers and gusts. In a previous study, it was shown that Theodorsen's and Wagner's unsteady aerodynamic models agree with force data from DNS

Rowley, Clarence W.

322

Number-phase uncertainty relations: Verification by balanced homodyne measurement

Science Journals Connector (OSTI)

It is shown that fundamental uncertainty relations between photon number and canonical phase of a single-mode optical field can be verified by means of a balanced homodyne measurement. All the relevant quantities can be sampled directly from the measured phase-dependent quadrature distribution.

T. Opatrný; M. Dakna; D.-G. Welsch

1998-03-01T23:59:59.000Z

323

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

324

Experimental realisation of Shor's quantum factoring algorithm using qubit recycling

Quantum computational algorithms exploit quantum mechanics to solve problems exponentially faster than the best classical algorithms. Shor's quantum algorithm for fast number factoring is a key example and the prime motivator in the international effort to realise a quantum computer. However, due to the substantial resource requirement, to date, there have been only four small-scale demonstrations. Here we address this resource demand and demonstrate a scalable version of Shor's algorithm in which the n qubit control register is replaced by a single qubit that is recycled n times: the total number of qubits is one third of that required in the standard protocol. Encoding the work register in higher-dimensional states, we implement a two-photon compiled algorithm to factor N=21. The algorithmic output is distinguishable from noise, in contrast to previous demonstrations. These results point to larger-scale implementations of Shor's algorithm by harnessing scalable resource reductions applicable to all physical architectures.

Enrique Martin-Lopez; Anthony Laing; Thomas Lawson; Roberto Alvarez; Xiao-Qi Zhou; Jeremy L. O'Brien

2011-11-17T23:59:59.000Z

325

Reducing Quantum Errors and Improving Large Scale Quantum Cryptography

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

326

Quantum Money with Classical Verification

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

327

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

328

Coherent control of quantum information

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

329

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

NATIONAL ENERGY POLICY NATIONAL ENERGY POLICY STATUS REPORT on Implementation of NEP Recommendations January, 2005 1 NEP RECOMMENDATIONS: STATUS OF IMPLEMENTATION Chapter 1 1. That the President issue an Executive Order to direct all federal agencies to include in any regulatory action that could significantly and adversely affect energy supplies, distribution, or use, a detailed statement of energy effects and alternatives in submissions to the Office of Management and Budget of proposed regulations covered and all notices of proposed regulations published in the Federal Register. STATUS: IMPLEMENTED. In May 2001, President Bush issued Executive Order 13211 requiring federal agencies to include, in any regulatory action that could significantly and

330

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

SWMU 161 C-743 Trainina Trailer Comolex- Soil Backfill UNIT NAME: . REGULATORY STATUS: AOC LOCATION: Southwest of C-743 building APPROXIMATE DIMENSIONS: 200 feet wide by 200 feet...

331

Instantaneous Quantum Computation

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

332

Efficient Distributed Quantum Computing

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

333

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

334

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 García de Abajo; J. B. Pendry

2012-08-21T23:59:59.000Z

335

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

336

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

337

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...

338

Science Journals Connector (OSTI)

Quantum Junction Solar Cells ... § Department of Electrical and Computer Engineering, University of Toronto, 10 King’s 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

339

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

340

QUANTUM CONVERSION IN PHOTOSYNTHESIS

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

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

341

All-Optical Switching Using the Quantum Zeno Effect and Two-Photon Absorption

We have previously shown that the quantum Zeno effect can be used to implement quantum logic gates for quantum computing applications, where the Zeno effect was produced using a strong two-photon absorbing medium. Here we show that the Zeno effect can also be used to implement classical logic gates whose inputs and outputs are high-intensity fields (coherent states). The operation of the devices can be understood using a quasi-static analysis, and their switching times are calculated using a dynamic approach. The two-photon absorption coefficient of rubidium vapor is shown to allow operation of these devices at relatively low power levels.

B. C. Jacobs; J. D. Franson

2009-05-08T23:59:59.000Z

342

Formulation of functional theory for pairing with particle number restoration

The restoration of particle number within energy density functional theory is analyzed. It is shown that the standard method based on configuration mixing leads to a functional of both the projected and nonprojected densities. As an alternative that might be advantageous for mass models, nuclear dynamics, and thermodynamics, we propose to formulate the functional in terms directly of the one-body and two-body density matrices of the state with good particle number. Our approach does not contain the pathologies recently observed when restoring the particle number in an energy density functional framework based on transition density matrices and can eventually be applied with functionals having arbitrary density dependencies.

Hupin, Guillaume; Lacroix, Denis [Grand Accelerateur National d'Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, F-14076 Caen (France); Bender, Michael [Universite Bordeaux, Centre d'Etudes Nucleaires de Bordeaux Gradignan, UMR5797, F-33175 Gradignan (France); CNRS/IN2P3, Centre d'Etudes Nucleaires de Bordeaux Gradignan, UMR5797, F-33175 Gradignan (France)

2011-07-15T23:59:59.000Z

343

UNIFORM NON AMENABILITY AND 2 BETTI NUMBERS MIKAEL PICHOT AND STEPHANE VASSOUT

UNIFORM NON AMENABILITY AND 2 BETTI NUMBERS MIKAÂ¨EL PICHOT AND STÂ´EPHANE VASSOUT Abstract. It is shown that 1() h() for any countable group , where 1() is the first 2 Betti number and h() the uniform Cheeger constant. In particular a countable group with non vanishing first 2 Betti number is uniformly non

Vassout, StÃ©phane

344

Compendium of Experimental Cetane Numbers

This report is an updated version of the 2004 Compendium of Experimental Cetane Number Data and presents a compilation of measured cetane numbers for pure chemical compounds. It includes all available single compound cetane number data found in the scientific literature up until March 2014 as well as a number of unpublished values, most measured over the past decade at the National Renewable Energy Laboratory. This Compendium contains cetane values for 389 pure compounds, including 189 hydrocarbons and 201 oxygenates. More than 250 individual measurements are new to this version of the Compendium. For many compounds, numerous measurements are included, often collected by different researchers using different methods. Cetane number is a relative ranking of a fuel's autoignition characteristics for use in compression ignition engines; it is based on the amount of time between fuel injection and ignition, also known as ignition delay. The cetane number is typically measured either in a single-cylinder engine or a constant volume combustion chamber. Values in the previous Compendium derived from octane numbers have been removed, and replaced with a brief analysis of the correlation between cetane numbers and octane numbers. The discussion on the accuracy and precision of the most commonly used methods for measuring cetane has been expanded and the data has been annotated extensively to provide additional information that will help the reader judge the relative reliability of individual results.

Yanowitz, J.; Ratcliff, M. A.; McCormick, R. L.; Taylor, J. D.; Murphy, M. J.

2014-08-01T23:59:59.000Z

345

Generalized quantum state discrimination problems

We address a broad class of optimization problems of finding quantum measurements, which includes the problems of finding an optimal measurement in the Bayes criterion and a measurement maximizing the average success probability with a fixed rate of inconclusive results. Our approach can deal with any problem in which each of the objective and constraint functions is formulated by the sum of the traces of the multiplication of a Hermitian operator and a detection operator. We first derive dual problems and necessary and sufficient conditions for an optimal measurement. We also consider the minimax version of these problems and provide necessary and sufficient conditions for a minimax solution. Finally, for optimization problem having a certain symmetry, there exists an optimal solution with the same symmetry. Examples are shown to illustrate how our results can be used.

Kenji Nakahira; Kentaro Kato; Tsuyoshi Sasaki Usuda

2015-01-23T23:59:59.000Z

346

The SL(2,R)WZWN string model as a deformed oscillator and its classical-quantum string regimes

We study the SL(2,R) WZWN string model describing bosonic string theory in AdS_3 space-time as a deformed oscillator together with its mass spectrum and the string modified SL(2,R) uncertainty relation. The SL(2,R) string oscillator is far more quantum (with higher quantum uncertainty) and more excited than the non deformed one. This is accompassed by the highly excited string mass spectrum which is drastically changed with respect to the low excited one. The highly excited quantum string regime and the low excited semiclassical regime of the SL(2,R) string model are described and shown to be the quantum-classical dual of each other in the precise sense of the usual classical-quantum duality. This classical-quantum realization is not assumed nor conjectured. The quantum regime (high curvature) displays a modified Heisenberg's uncertainty relation, while the classical (low curvature) regime has the usual quantum mechanics uncertainty principle.

M. Ramon Medrano; N. G. Sanchez

2006-06-12T23:59:59.000Z

347

Quantum Simulations for Dense Matter

High pressure systems are important, for example, to understand the interiors of giant planets (Jupiter and Saturn), for experiments at NIF (the National Ignition Facility at Livermore) related to inertially confined fusion and for other interests of DOE. In this project, we are developing innovative simulation methods (Quantum Monte Carlo methods) to allow more accurate calculation of properties of systems under extreme conditions of pressure and temperature. These methods can use the power of current day supercomputers made of very many processors, starting from the basic equations of physics to model quantum phenomena important at the microscopic scale. During the grant period, we have settled two important questions of the physics of hydrogen and helium under extreme conditions. We have found the pressures and temperatures when hydrogen and helium mix together; this is important to understand the difference of the interiors of the planets Jupiter and Saturn. Secondly, we have shown that there exists a sharp transition as a function of pressure between molecular and atomic liquid hydrogen at temperatures below 2000K. This prediction can be confirmed with high pressure experiments.

Ceperley, David M

2010-06-07T23:59:59.000Z

348

Majorization-preserving quantum channels

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

349

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...

350

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 sun’s rays. ...

JYLLIAN KEMSLEY

2012-02-19T23:59:59.000Z

351

On the Role of Hadamard Gates in Quantum Circuits

We study a reduced quantum circuit computation paradigm in which the only allowable gates either permute the computational basis states or else apply a "global Hadamard operation", i.e. apply a Hadamard operation to every qubit simultaneously. In this model, we discuss complexity bounds (lower-bounding the number of global Hadamard operations) for common quantum algorithms : we illustrate upper bounds for Shor's Algorithm, and prove lower bounds for Grover's Algorithm. We also use our formalism to display a gate that is neither quantum-universal nor classically simulable, on the assumption that Integer Factoring is not in BPP.

Dan Shepherd

2005-08-22T23:59:59.000Z

352

Wave-Packet Revivals for Quantum Systems with Nondegenerate Energies

The revival structure of wave packets is examined for quantum systems having energies that depend on two nondegenerate quantum numbers. For such systems, the evolution of the wave packet is controlled by two classical periods and three revival times. These wave packets exhibit quantum beats in the initial motion as well as new types of long-term revivals. The issue of whether fractional revivals can form is addressed. We present an analytical proof showing that at certain times equal to rational fractions of the revival times the wave packet can reform as a sum of subsidiary waves and that both conventional and new types of fractional revivals can occur.

Robert Bluhm; Alan Kostelecky; Bogdan Tudose

1996-09-26T23:59:59.000Z

353

Quantum effects in electron beam pumped GaAs

Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.

Yahia, M. E. [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt) [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Azzouz, I. M. [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt)] [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)] [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)

2013-08-19T23:59:59.000Z

354

Real-world Quantum Sensors: Evaluating Resources for Precision Measurement

Quantum physics holds the promise of enabling certain tasks with better performance than possible when only classical resources are employed. The quantum phenomena present in many experiments signify nonclassical behavior, but do not always imply superior performance. Quantifying the enhancement achieved from quantum behavior requires careful analysis of the resources involved. We analyze the specific case of parameter estimation using an optical interferometer, where increased precision can be achieved using quantum probe states. Common performance measures are examined and it is shown that some overestimate the improvement. For the simplest experimental case we compare the different measures and show this overestimate explicitly. We give the preferred analysis of real-world experiments and calculate benchmark values for experimental parameters necessary to realize a precision enhancement.

Nicholas Thomas-Peter; Brian J Smith; Animesh Datta; Lijian Zhang; Uwe Dorner; Ian A Walmsley

2011-05-19T23:59:59.000Z

355

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

356

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

357

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

358

Isotope - based Quantum Information

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

359

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

360

Quantum Spacetime Phenomenology

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

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

361

Science Journals Connector (OSTI)

We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode...??~?6.15 ?m and a bro...

Ning Zhuo; Feng Qi Liu; Jin Chuan Zhang; Li Jun Wang…

2014-03-01T23:59:59.000Z

362

Economical ontological models for discrete quantum systems

Science Journals Connector (OSTI)

I use the recently proposed framework of ontological models (N. Harrigan, T. Rudolph, and S. Aaronson, e-print arXiv:0709.1149) to obtain economical models for the results of tomographically complete sets of measurements on finite-dimensional quantum systems. I describe a procedure that simplifies the models by decreasing the number of necessary ontic states and present an explicit model with just 33 ontic states for a qutrit.

Ernesto F. Galvão

2009-08-05T23:59:59.000Z

363

Economical ontological models for discrete quantum systems

I use the recently proposed framework of ontological models [Harrigan et al., arXiv:0709.1149v2] to obtain economical models for results of tomographically complete sets of measurements on finite-dimensional quantum systems. I describe a procedure that simplifies the models by decreasing the number of necessary ontic states, and present an explicit model with just 33 ontic states for a qutrit.

Ernesto F. Galvao

2009-02-13T23:59:59.000Z

364

Practical security analysis of a quantum stream cipher by the Yuen 2000 protocol

Science Journals Connector (OSTI)

There exists a great gap between one-time pad with perfect secrecy and conventional mathematical encryption. The Yuen 2000 (Y00) protocol or ?? scheme may provide a protocol which covers from the conventional security to the ultimate one, depending on implementations. This paper presents the complexity-theoretic security analysis on some models of the Y00 protocol with nonlinear pseudo-random-number-generator and quantum noise diffusion mapping (QDM). Algebraic attacks and fast correlation attacks are applied with a model of the Y00 protocol with nonlinear filtering like the Toyocrypt stream cipher as the running key generator, and it is shown that these attacks in principle do not work on such models even when the mapping between running key and quantum state signal is fixed. In addition, a security property of the Y00 protocol with QDM is clarified. Consequently, we show that the Y00 protocol has a potential which cannot be realized by conventional cryptography and that it goes beyond mathematical encryption with physical encryption.

Osamu Hirota

2007-09-07T23:59:59.000Z

365

Fibred Coalgebraic Logic and Quantum Protocols

Motivated by applications in modelling quantum systems using coalgebraic techniques, we introduce a fibred coalgebraic logic. Our approach extends the conventional predicate lifting semantics with additional modalities relating conditions on different fibres. As this fibred setting will typically involve multiple signature functors, the logic incorporates a calculus of modalities enabling the construction of new modalities using various composition operations. We extend the semantics of coalgebraic logic to this setting, and prove that this extension respects behavioural equivalence. We show how properties of the semantics of modalities are preserved under composition operations, and then apply the calculational aspect of our logic to produce an expressive set of modalities for reasoning about quantum systems, building these modalities up from simpler components. We then demonstrate how these modalities can describe some standard quantum protocols. The novel features of our logic are shown to allow for a uniform description of unitary evolution, and support local reasoning such as "Alice's qubit satisfies condition" as is common when discussing quantum protocols.

Daniel Marsden

2014-12-30T23:59:59.000Z

366

Quantum-noise quenching in quantum tweezers

The efficiency of extracting single atoms or molecules from an ultracold bosonic reservoir is theoretically investigated for a protocol based on lasers, coupling the hyperfine state in which the atoms form a condensate to another stable state, in which the atom experiences a tight potential in the regime of collisional blockade, the quantum tweezers. The transfer efficiency into the single-atom ground state of the tight trap is fundamentally limited by the collective modes of the condensate, which are thermally and dynamically excited and constitute the ultimate noise sources. This quantum noise can be quenched for sufficiently long laser pulses, thereby achieving high efficiencies, and showing that this protocol can be applied for quantum information processing based on tweezer traps for neutral atoms.

Zippilli, Stefano; Lutz, Eric; Morigi, Giovanna; Schleich, Wolfgang

2010-01-01T23:59:59.000Z

367

Reasoning about quantum knowledge

We construct a formal framework for investigating epistemic and temporal notions in the context of distributed quantum computation. While we rely on structures developed earlier, we stress that our notion of quantum knowledge makes sense more generally in any agent-based model for distributed quantum systems. Several arguments are given to support our view that an agent's possibility relation should not be based on the reduced density matrix, but rather on local classical states and local quantum operations. In this way, we are able to analyse distributed primitives such as superdense coding and teleportation, obtaining interesting conclusions as to how the knowledge of individual agents evolves. We show explicitly that the knowledge transfer in teleportation is essentially classical, in that eventually, the receiving agent knows that its state is equal to the initial state of the sender. The relevant epistemic statements for teleportation deal with this correlation rather than with the actual quantum state, which is unknown throughout the protocol.

Ellie D'Hondt; Prakash Panangaden

2005-07-19T23:59:59.000Z

368

Quantum Field Theory on Certain Non-Globally Hyperbolic Spacetimes

We study real linear scalar field theory on two simple non-globally hyperbolic spacetimes containing closed timelike curves within the framework proposed by Kay for algebraic quantum field theory on non-globally hyperbolic spacetimes. In this context, a spacetime (M,g) is said to be `F-quantum compatible' with a field theory if it admits a *-algebra of local observables for that theory which satisfies a locality condition known as `F-locality'. Kay's proposal is that, in formulating algebraic quantum field theory on $(M,g)$, F-locality should be imposed as a necessary condition on the *-algebra of observables. The spacetimes studied are the 2- and 4-dimensional spacelike cylinders (Minkowski space quotiented by a timelike translation). Kay has shown that the 4-dimensional spacelike cylinder is F-quantum compatible with massless fields. We prove that it is also F-quantum compatible with massive fields and prove the F-quantum compatibility of the 2-dimensional spacelike cylinder with both massive and massless fields. In each case, F-quantum compatibility is proved by constructing a suitable F-local algebra.

C. J. Fewster; A. Higuchi

1995-08-24T23:59:59.000Z

369

Effective equations for the quantum pendulum from momentous quantum mechanics

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

370

Quantum Degrees of Freedom, Quantum Integrability and Entanglment Generators

Dynamical algebra notion of quantum degrees of freedom is utilized to study the relation between quantum dynamical integrability and generalized entanglement. It is argued that a quantum dynamical system generates generalized entanglement by internal dynamics if and only if it is quantum non-integrable. Several examples are used to illustrate the relation.

Nikola Buric

2010-03-26T23:59:59.000Z

371

Full counting statistics as a probe of quantum coherence in a side-coupled double quantum dot system

We study theoretically the full counting statistics of electron transport through side-coupled double quantum dot (QD) based on an efficient particle-number-resolved master equation. It is demonstrated that the high-order cumulants of transport current are more sensitive to the quantum coherence than the average current, which can be used to probe the quantum coherence of the considered double QD system. Especially, quantum coherence plays a crucial role in determining whether the super-Poissonian noise occurs in the weak inter-dot hopping coupling regime depending on the corresponding QD-lead coupling, and the corresponding values of super-Poissonian noise can be relatively enhanced when considering the spins of conduction electrons. Moreover, this super-Poissonian noise bias range depends on the singly-occupied eigenstates of the system, which thus suggests a tunable super-Poissonian noise device. The occurrence-mechanism of super-Poissonian noise can be understood in terms of the interplay of quantum coherence and effective competition between fast-and-slow transport channels. -- Highlights: •The FCS can be used to probe the quantum coherence of side-coupled double QD system. •Probing quantum coherence using FCS may permit experimental tests in the near future. •The current noise characteristics depend on the quantum coherence of this QD system. •The super-Poissonian noise can be enhanced when considering conduction electron spin. •The side-coupled double QD system suggests a tunable super-Poissonian noise device.

Xue, Hai-Bin, E-mail: xuehaibin@tyut.edu.cn

2013-12-15T23:59:59.000Z

372

RNG: A Practitioner's Overview Random Number Generation

RNG: A Practitioner's Overview Random Number Generation A Practitioner's Overview Prof. Michael and Monte Carlo Methods Pseudorandom number generation Types of pseudorandom numbers Properties of these pseudorandom numbers Parallelization of pseudorandom number generators New directions for SPRNG Quasirandom

Mascagni, Michael

373

Properties of Open Quantum Walks on $\\mathbb{Z}$

A connection between the asymptotic behavior of the open quantum walk and the spectrum of a generalized quantum coins is studied. For the case of simultaneously diagonalizable transition operators an exact expression for probability distribution of the position of the walker for arbitrary number of steps is found. For a large number of steps the probability distribution consist of maximally two "soliton"-like solution and a certain number of Gaussian distributions. The number of different contributions to the final probability distribution is equal to the number of distinct absolute values in the spectrum of the transition operators. The presence of the zeros in spectrum is an indicator of the "soliton"-like solutions in the probability distribution.

I. Sinayskiy; F. Petruccione

2014-02-06T23:59:59.000Z

374

Quantum tunneling in the adiabatic Dicke model

The Dicke model describes N two-level atoms interacting with a single-mode bosonic field and exhibits a second-order phase transition from the normal to the superradiant phase. The energy levels are not degenerate in the normal phase but have degeneracy in the superradiant phase, where quantum tunneling occurs. By means of the Born-Oppenheimer approximation and the instanton method in quantum field theory, the tunneling splitting, inversely proportional to the tunneling rate for the adiabatic Dicke model, in the superradiant phase can be evaluated explicitly. It is shown that the tunneling splitting vanishes as exp(-N) for large N, whereas for small N it disappears as {radical}(N)/exp(N). The dependence of the tunneling splitting on the relevant parameters, especially on the atom-field coupling strength, is also discussed.

Chen Gang [Department of Physics, Shaoxing College of Arts and Sciences, Shaoxing 312000 (China); Institute of Theoretical Physics, Shanxi University, Taiyuan 030006 (China); Chen Zidong [Department of Physics, Shaoxing College of Arts and Sciences, Shaoxing 312000 (China); Liang Jiuqing [Institute of Theoretical Physics, Shanxi University, Taiyuan 030006 (China)

2007-10-15T23:59:59.000Z

375

Comment on 'Nonlocality, Counterfactuals and Quantum Mechanics'

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

376

Quantum Rainbow Cosmological Model With Perfect Fluid

Isotropic quantum cosmological perfect fluid model is studied in the formalism of Rainbow gravity. It is found that the only surviving matter degree of freedom played the role of cosmic time. With the suitable choice of the Rainbow functions it is possible to find the wave packet naturally from the superposition of the wave functions of the Schr$\\ddot{o}$dinger-Wheeler-deWitt equation. The many-worlds interpretation of quantum mechanics is applied to investigate the behavior of the scale factor and the behavior is found to depend on the operator ordering. It is shown that the model in the Rainbow framework may avoid singularity yielding a bouncing non-singular universe.

Majumder, Barun

2013-01-01T23:59:59.000Z

377

The work described in this thesis centers on inertialess motion at low Reynolds numbers at the crossroad between biofluids and microfluids. Here we address questions regarding locomotion of micro-swimmers, transport of ...

Tam, Daniel See Wai, 1980-

2008-01-01T23:59:59.000Z

378

Departmental Business Instrument Numbering System

Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]

To prescribe procedures for assigning identifying numbers to all Department of Energy (DOE), including the National Nuclear Security Administration, business instruments. Cancels DOE 1331.2B. Canceled by DOE O 540.1A.

2000-12-05T23:59:59.000Z

379

Departmental Business Instrument Numbering System

Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]

The Order prescribes the procedures for assigning identifying numbers to all Department of Energy (DOE) and National Nuclear Security Administration (NNSA) business instruments. Cancels DOE O 540.1. Canceled by DOE O 540.1B.

2005-01-27T23:59:59.000Z

380

Science Journals Connector (OSTI)

Recently the quantum trajectory method (QTM) has been utilized in solving several quantum mechanical wave packet scattering problems including barrier transmission and electronic nonadiabatic dynamics. By propagating the real-valued action and amplitude functions in the Lagrangian frame only a fraction of the grid points needed for Eulerian fixed-grid methods are used while still obtaining accurate solutions. Difficulties arise however near wave functionnodes and in regions of sharp oscillatory features and because of this many quantum mechanical problems have not yet been amenable to solution with the QTM. This study proposes a hybrid of both the Lagrangian and Eulerian techniques in what is termed the arbitrary Lagrangian–Eulerian method (ALE). In the ALE method an additional equation of motion governing the momentum of the grid points is coupled into the quantum hydrodynamicequations. These new “quasi-” Bohmian trajectories can be dynamically adapted to the emergent features of the time evolving hydrodynamic fields and are non-Lagrangian. In this study it is shown that the ALE method applied to an uphill ramp potential that was previously unsolvable by the current Lagrangian QTM not only yields stable transmission probabilities with accuracies comparable to that of a high resolution Eulerian method but does so with a small number of grid points and for extremely long propagation times. To determine the grid point positions at each new time an equidistribution method is used that is constructed similar to the stiffness matrix of a classical spring system in equilibrium. Each “smart” spring is dependent on a local function M(x) called the monitor function which can sense gradients or curvatures of the fields surrounding its position. To constrain grid points from having zero separation and possible overlap a new system of equations is derived that includes a minimum separation parameter which prevents this from occurring.

Corey J. Trahan; Robert E. Wyatt

2003-01-01T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

381

Nonlinear friction in quantum mechanics

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

382

AN INTRODUCTION TO QUANTUM OPTICS...

AN INTRODUCTION TO QUANTUM OPTICS... ...the light as you've never seen before... Optics:http://science.howstuffworks.com/laser5.htm #12;5 DEFINITION Quantum Optics: "Quantum optics is a field in quantum physics, dealing OPTICS OPERATORS Light is described in terms of field operators for creation and annihilation of photons

Palffy-Muhoray, Peter

383

California Natural Gas Number of Residential Consumers (Number of Elements)

U.S. Energy Information Administration (EIA) Indexed Site

Residential Consumers (Number of Elements) Residential Consumers (Number of Elements) California Natural Gas Number of Residential Consumers (Number of Elements) Decade Year-0 Year-1 Year-2 Year-3 Year-4 Year-5 Year-6 Year-7 Year-8 Year-9 1980's 7,626 7,904,858 8,113,034 8,313,776 1990's 8,497,848 8,634,774 8,680,613 8,726,187 8,790,733 8,865,541 8,969,308 9,060,473 9,181,928 9,331,206 2000's 9,370,797 9,603,122 9,726,642 9,803,311 9,957,412 10,124,433 10,329,224 10,439,220 10,515,162 10,510,950 2010's 10,542,584 10,625,190 10,681,916 - = No Data Reported; -- = Not Applicable; NA = Not Available; W = Withheld to avoid disclosure of individual company data. Release Date: 12/12/2013 Next Release Date: 1/7/2014 Referring Pages: Number of Natural Gas Residential

384

Finite Approximations to Quantum Physics: Quantum Points and their Bundles

There exists a physically well motivated method for approximating manifolds by certain topological spaces with a finite or a countable set of points. These spaces, which are partially ordered sets (posets) have the power to effectively reproduce important topological features of continuum physics like winding numbers and fractional statistics, and that too often with just a few points. In this work, we develop the essential tools for doing quantum physics on posets. The poset approach to covering space quantization, soliton physics, gauge theories and the Dirac equation are discussed with emphasis on physically important topological aspects. These ideas are illustrated by simple examples like the covering space quantization of a particle on a circle, and the sine-Gordon solitons.

A. P. Balachandran; G. Bimonte; E. Ercolessi; P. Teotonio-Sobrinho

1993-10-04T23:59:59.000Z

385

Broken gauge symmetry in a Bose gas with constant particle number

The existence of broken gauge symmetries in Bose-Einstein condensates is still controversially discussed in science, since it would not conserve the total number of particles. Here, it is shown for the first time that non-random condensate and non-condensate phase distributions may arise from local particle number breaking in a Bose gas with constant particle number, while the global U(1)-gauge symmetry of the system is preserved due to particle number conservation.

Alexej Schelle

2014-12-13T23:59:59.000Z

386

How to test the gauge-invariant non-local quantum dynamics of the Aharonov-Bohm effect

The gauge invariant non local quantum dynamics of the Aharonov-Bohm effect can be tested experimentally by measuring the instantaneous shift of the velocity distribution occurring when the particle passes by the flux line. It is shown that in relativistic quantum theory it is possible to measure the instantaneous velocity with accuracy sufficient to detect the change of the velocity distribution. In non relativistic quantum theory the instantaneous velocity can be measured to any desired accuracy.

T. Kaufherr

2014-11-11T23:59:59.000Z

387

Ising Model Coupled to Three-Dimensional Quantum Gravity

We have performed Monte Carlo simulations of the Ising model coupled to three-dimensional quantum gravity based on a summation over dynamical triangulations. These were done both in the microcanonical ensemble, with the number of points in the triangulation and the number of Ising spins fixed, and in the grand canoncal ensemble. We have investigated the two possible cases of the spins living on the vertices of the triangulation (``diect'' case) and the spins living in the middle of the tetrahedra (``dual'' case). We observed phase transitions which are probably second order, and found that the dual implementation more effectively couples the spins to the quantum gravity.

C. F. Baillie

1992-05-09T23:59:59.000Z

388

Layered architecture for quantum computing

We develop a layered quantum computer architecture, which is a systematic framework for tackling the individual challenges of developing a quantum computer while constructing a cohesive device design. We discuss many of the prominent techniques for implementing circuit-model quantum computing and introduce several new methods, with an emphasis on employing surface code quantum error correction. In doing so, we propose a new quantum computer architecture based on optical control of quantum dots. The timescales of physical hardware operations and logical, error-corrected quantum gates differ by several orders of magnitude. By dividing functionality into layers, we can design and analyze subsystems independently, demonstrating the value of our layered architectural approach. Using this concrete hardware platform, we provide resource analysis for executing fault-tolerant quantum algorithms for integer factoring and quantum simulation, finding that the quantum dot architecture we study could solve such problems on the timescale of days.

N. Cody Jones; Rodney Van Meter; Austin G. Fowler; Peter L. McMahon; Jungsang Kim; Thaddeus D. Ladd; Yoshihisa Yamamoto

2012-09-27T23:59:59.000Z

389

Revising the trade-off between the number of agents and agent intelligence

Science Journals Connector (OSTI)

Emergent agents are a promising approach to handle complex systems. Agent intelligence is thereby either defined by the number of states and the state transition function or the length of their steering programs. Evolution has shown to be successful ...

Marcus Komann; Dietmar Fey

2010-04-01T23:59:59.000Z

390

Quantum technology: the second quantum revolution

Science Journals Connector (OSTI)

...be an electron or nuclear spin in a molecule...the Coulomb energy cost of adding one extra...1667 A B A' B' C D BS M M S - 0 2.0 1...resolution at low cost. In addition to writing...A silicon-based nuclear spin quantum computer...

2003-01-01T23:59:59.000Z

391

Laboratory, Los Alamos, New Mexico 87545, USA (Received 11 August 2010; revised manuscript received 17 and polaron transport through finite quantum structures in the framework of the one-dimensional Holstein model a quantum wall or dot is generally accompanied by strong phonon number fluctuations due to phonon emission

Fehske, Holger

392

Quantum free-energy differences from nonequilibrium path integrals. II. Convergence properties July 2008; published 2 October 2008 Nonequilibrium path-integral methods for computing quantum free-energy with the purpose of establishing the convergence properties of the work distribution and free energy as the number

Schofield, Jeremy

393

Intrinsic Time Quantum Geometrodynamics

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

394

Simulation of a quantum phase transition of polaritons with trapped ions P. A. Ivanov,1,2,* S. S to obtain signatures of the quantum phase transitions even with a small number of ions. DOI: 10.1103/Phys 2009; published 3 December 2009 We present a system for the simulation of quantum phase transitions

Pfeifer, Holger

395

Increasing the power of the verifier in Quantum Zero Knowledge

In quantum zero knowledge, the assumption was made that the verifier is only using unitary operations. Under this assumption, many nice properties have been shown about quantum zero knowledge, including the fact that Honest-Verifier Quantum Statistical Zero Knowledge (HVQSZK) is equal to Cheating-Verifier Quantum Statistical Zero Knowledge (QSZK) (see [Wat02,Wat06]). In this paper, we study what happens when we allow an honest verifier to flip some coins in addition to using unitary operations. Flipping a coin is a non-unitary operation but doesn't seem at first to enhance the cheating possibilities of the verifier since a classical honest verifier can flip coins. In this setting, we show an unexpected result: any classical Interactive Proof has an Honest-Verifier Quantum Statistical Zero Knowledge proof with coins. Note that in the classical case, honest verifier SZK is no more powerful than SZK and hence it is not believed to contain even NP. On the other hand, in the case of cheating verifiers, we show that Quantum Statistical Zero Knowledge where the verifier applies any non-unitary operation is equal to Quantum Zero-Knowledge where the verifier uses only unitaries. One can think of our results in two complementary ways. If we would like to use the honest verifier model as a means to study the general model by taking advantage of their equivalence, then it is imperative to use the unitary definition without coins, since with the general one this equivalence is most probably not true. On the other hand, if we would like to use quantum zero knowledge protocols in a cryptographic scenario where the honest-but-curious model is sufficient, then adding the unitary constraint severely decreases the power of quantum zero knowledge protocols.

André Chailloux; Iordanis Kerenidis

2007-11-26T23:59:59.000Z

396

Special Feature: Quantum Measurement Standards

Science Journals Connector (OSTI)

This special feature is intended to present a comprehensive review of the present state and novel trends in the field of quantum measurement standards. Most of the present metrological research is concentrated on establishing and strengthening the links between the units and fundamental constants. This will be demonstrated in the nine articles in this feature. The first four articles are devoted to time, frequency and length metrology. They describe quantum standards that are used or intended to be used for the realization of the SI base units of time and length, the second and the metre. The two units are related to each other by an adopted fixed value of the speed of light in vacuum and the second is at present defined by the energy difference (frequency) of a hyperfine transition in the ground state of caesium. The special feature starts with the discussion of caesium atomic clocks as direct realizations of the second and as a basis for other standards (e.g. the Josephson voltage quantum standard). Whereas Cs atomic clocks still provide us with the most accurate realization of the second, optical frequency standards based on cold trapped ions or cold atoms may eventually lead us to even lower uncertainty levels and may replace the present definition of the second by an optical transition. This situation is described in the contribution on optical frequency standards based on trapped single ions. Since optical frequency standards are also needed as wavelength standards in length metrology, the third contribution reviews the definition of the metre. It describes the different methods of realization, in particular by optical frequency standards including standards based on cold atoms. The use of optical frequency standards in time and length metrology requires the precise knowledge of their frequencies. Methods of optical frequency measurements based on various methods—including frequency comb generators—are discussed in the fourth article. Turning to the electric units, the discovery of two macroscopic quantum effects, the Josephson effect—discovered in the early sixties—and the quantum Hall effect—discovered in 1980—allowed the linking of electric units to fundamental constants. By use of the Josephson effect quantized voltage values are realized as multiples of the product of a certain frequency and of the superconducting flux quantum (h/2e). Quantized resistance values are realized with the quantum Hall effect as submultiples of h/e2, where this fundamental constant can also be interpreted as the quotient of the flux quantum of a normal conductor and the elementary charge. The metrological application became much easier by making use of the possibility of designing and manufacturing appropriate samples with microelectronic techniques. Since 1990 all calibrations of voltages or resistances worldwide have been based on these two quantum effects. Relative uncertainties of the order of 10-9 are obtained. International comparisons have proved that the calibration results in different laboratories also agree within relative uncertainties of a few parts in 109. Great attempts have also been made to realize a current quantum standard by counting single electrons. The Josephson effect and its application are described by Kohlmann and co-workers. The quantum Hall effect is only briefly described in this issue of Measurement Science and Technology since a comprehensive review article by Jeckelmann and Jeanneret appeared recently [1]. The unit of mass, the kilogram, is the only base unit in the SI that is derived from an artefact. Therefore one major task of today's metrological research is the linking of the unit of mass to a fundamental constant. There are two rival attempts: the comparison of mechanical and electrical power using the watt-balance and the counting of a large number of identical particles, like atoms or ions. The watt balance was pioneered by B Kibble. This experiment consists of two parts. A balance in equilibrium is opposed to a gravitational force and to a force on a coil fed by a current and opp

Erich Braun; Jürgen Helmcke

2003-01-01T23:59:59.000Z

397

Architecture of a Quantum Multicomputer Optimized for Shor's Factoring Algorithm

The quantum multicomputer consists of a large number of small nodes and a qubus interconnect for creating entangled state between the nodes. The primary metric chosen is the performance of such a system on Shor's algorithm for factoring large numbers: specifically, the quantum modular exponentiation step that is the computational bottleneck. This dissertation introduces a number of optimizations for the modular exponentiation. My algorithms reduce the latency, or circuit depth, to complete the modular exponentiation of an n-bit number from O(n^3) to O(n log^2 n) or O(n^2 log n), depending on architecture. Calculations show that these algorithms are one million times and thirteen thousand times faster, when factoring a 6,000-bit number, depending on architecture. Extending to the quantum multicomputer, five different qubus interconnect topologies are considered, and two forms of carry-ripple adder are found to be the fastest for a wide range of performance parameters. The links in the quantum multicomputer are serial; parallel links would provide only very modest improvements in system reliability and performance. Two levels of the Steane [[23,1,7

Rodney Doyle Van Meter III

2006-07-11T23:59:59.000Z

398

Quantum Geometry Phenomenology: Angle and Semiclassical States

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used to develop a model of angular corrections to local, continuum flat-space 3-geometries. The physical effects involve neither breaking of local Lorentz invariance nor Planck scale suppression, but rather reply on only the combinatorics of SU(2) recouping theory. Bhabha scattering is discussed as an example of how the effects might be observationally accessible.

Seth A. Major

2011-12-19T23:59:59.000Z

399

A Global Optimization Approach to Quantum Mechanics

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

400

Physical Significance of Operators in Quantum Optics

Science Journals Connector (OSTI)

The relation between normally ordered and unordered products of creation and annihilation operators is examined, and it is emphasized that the former correspond to counting correlations and the latter to counting moments. Both can be measured. It is shown that there exists a particularly simple relation between the generating functions for the two kinds of products. This relation can also be obtained by semiclassical considerations, which give more insight into its significance. The result provides further indication of the very close connection between the semiclassical and quantum-mechanical theories of optical coherence.

L. Mandel

1964-11-23T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

401

Quantum Otto cycle efficiency on coupled qudits

Properties of the coupled particles with spin 3/2 (quartits) in a constant magnetic field, as a working substance in the quantum Otto cycle of the heat engine, are considered. It is shown that this system as a converter of heat energy in work (i) shows the efficiency 1 at the negative absolute temperatures of heat baths, (ii) at the temperatures of the opposite sign the efficiency approaches to 1, (iii) at the positive temperatures of heat baths antiferromagnetic interaction raises efficiency threefold in comparison with uncoupled particles.

E. A. Ivanchenko

2014-12-22T23:59:59.000Z

402

Demonstration of a Scalable, Multiplexed Ion Trap for Quantum Information Processing

A scalable, multiplexed ion trap for quantum information processing is fabricated and tested. The trap design and fabrication process are optimized for scalability to small trap size and large numbers of interconnected ...

Leibrandt, David R.

403

Design of Laser Transition Oscillator Strength for THz Quantum Cascade Lasers

Science Journals Connector (OSTI)

The density matrix based model is employed to design number of THz quantum cascade lasers with various laser oscillator strengths. The optimum oscillator strength varies between 0.35...

Fathololoumi, Saeed; Dupont, Emmanuel; Laframboise, Sylvain R; Wasilewski, Zbigniew R; Ban, Dayan; Liu, Hc

404

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

Document ID Number: Document ID Number: RL-721 REV 4 NEPA REVIEW SCREENING FORM DOE/CX-00066 I. Project Title: Nesting Bird Deterrent Study at the 241-C Tank Farm CX B3.8, "Outdoor Terrestrial Ecological and Environmental Research" II. Project Description and Location (including Time Period over which proposed action will occur and Project Dimensions - e.g., acres displaced/disturbed, excavation length/depth, area/location/number of buildings, etc.): Washington River Protection Solutions LLC (WRPS) will perform an outdoor, terrestrial ecological research study to attempt to control and deter nesting birds at the 241-C Tank Farm. This will be a preventative study to test possible methods for controlling &/or minimizing the presence and impacts of nesting birds inside the tank farm. A nesting bird

405

On rings of structural numbers

structural numbers over the set X, and let B(X) have the operations defined above with equality also as before. Theorem I. l. If X is any set, then B(X) is a commutative ring with identity. Proof. The structural number 0 is the additive identity element... with identity g. Definition I. 7. If A, B e S(X) then A'B = (P U q ( p e A, q e B, p Il q = &f and p U q can be formed in an odd number of ways). ~E1 t. 4. L t A = (( . b), (bj. 7 )) 4 B = ((b, c), (b), (a)) be in S(X) for some X. Then AD B = {{b, a), {a...

Powell, Wayne Bruce

2012-06-07T23:59:59.000Z

406

The production system is a theoretical model of computation relevant to the artificial intelligence field allowing for problem solving procedures such as hierarchical tree search. In this work we explore some of the connections between artificial intelligence and quantum computation by presenting a model for a quantum production system. Our approach focuses on initially developing a model for a reversible production system which is a simple mapping of Bennett's reversible Turing machine. We then expand on this result in order to accommodate for the requirements of quantum computation. We present the details of how our proposition can be used alongside Grover's algorithm in order to yield a speedup comparatively to its classical counterpart. We discuss the requirements associated with such a speedup and how it compares against a similar quantum hierarchical search approach.

Luís Tarrataca; Andreas Wichert

2015-02-06T23:59:59.000Z

407

Terahertz quantum cascade lasers

The development of the terahertz frequency range has long been impeded by the relative dearth of compact, coherent radiation sources of reasonable power. This thesis details the development of quantum cascade lasers (QCLs) ...

Williams, Benjamin S. (Benjamin Stanford), 1974-

2003-01-01T23:59:59.000Z

408

Parasupersymmetry in Quantum Graphs

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

409

Parasupersymmetry in Quantum Graphs

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

410

We show that quantum particles constrained to move along curves undergoing cyclic deformations acquire, in general, geometric phases. We treat explicitly an example, involving particular deformations of a circle, and ponder on potential applications.

C. Chryssomalakos; H. Hernandez; D. Gelbwaser-Klimovsky; E. Okon

2008-04-19T23:59:59.000Z

411

Geometrically frustrated quantum magnets

(cont.) more general lessons on frustrated quantum magnetism. At the end, we demonstrate some new mathematical tools on two other frustrated two-dimensional systems, and summarize our conclusions, with an outlook to remaining ...

NikoliÄ‡ , Predrag, 1974-

2004-01-01T23:59:59.000Z

412

Quantum kinetic theory with nonlocal coherence

In this thesis we develop a novel approximation scheme (eQPA), where the effects of nonlocal coherence are included in the kinetic approach to nonequilibrium quantum dynamics. The key element in our formalism is the finding of new singular shell solutions, located at $k_{0,z} = 0$ in the phase space of 2-point Wightman function, which describe the nonlocal quantum coherence between the ``opposite'' mass-shell excitations for spatially homogeneous and static planar symmetric problems, respectively. This phase space structure leads to a closed set of transport equations for the corresponding on-shell distribution functions $f$, providing an extension to the standard quantum Boltzmann equation. We have considered a number of applications to demonstrate the use of our formalism, including the Klein problem, quantum reflection from a CP-violating mass wall and coherent production of (fermionic and scalar) particles in an oscillating background. Our formalism should be of relevance for many problems in particle physics and cosmology, including baryogenesis and neutrino flavour oscillations in an inhomogeneous background.

Matti Herranen

2009-06-17T23:59:59.000Z

413

Baryon and lepton number violation in the Weinberg-Salam theory

This report discusses the concept of baryon and lepton number violation in the Weinberg-Salam theory. The topics discussed are: periodic vacua in quantum mechanics; tunnelling at finite temperature and classical thermal activation; calculation of the rate; an O(3) nonlinear sigma model; and the transition rate in the O(3) model. (LSP)

Mottola, E.

1989-01-01T23:59:59.000Z

414

Three-Pulse Photon Echo of Finite Numbers of Molecules: Single-Molecule Traces

Three-Pulse Photon Echo of Finite Numbers of Molecules: Single- Molecule Traces Hui Dong and Graham, 6227]. To avoid this drawback of ensemble measurements and evaluate single-molecule behavior, a quantum the fluctuations inherent to single molecules. The current method takes advantage of the coherent state

Fleming, Graham R.

415

We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in the quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using quantum statistical average. Furthermore based on our study, we give implication on the dynamics of phase transition.

Tomoko Uesugi; Masahiro Morikawa; Tetsuya Shiromizu

1996-06-26T23:59:59.000Z

416

QUANTUM ERROR CONTROL CODES A Dissertation by SALAH ABDELHAMID AWAD ALY AHMED Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 2008 Major... Subject: Computer Science QUANTUM ERROR CONTROL CODES A Dissertation by SALAH ABDELHAMID AWAD ALY AHMED Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY...

Abdelhamid Awad Aly Ahmed, Sala

2008-10-10T23:59:59.000Z

417

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

418

We review the field of Optical Quantum Computation, considering the various implementations that have been proposed and the experimental progress that has been made toward realizing them. We examine both linear and nonlinear approaches and both particle and field encodings. In particular we discuss the prospects for large scale optical quantum computing in terms of the most promising physical architectures and the technical requirements for realizing them.

T. C. Ralph; G. J. Pryde

2011-03-31T23:59:59.000Z

419

Quantum robots and environments

Science Journals Connector (OSTI)

Quantum robots and their interactions with environments of quantum systems are described, and their study justified. A quantum robot is a mobile quantum system that includes an on-board quantum computer and needed ancillary systems. Quantum robots carry out tasks whose goals include specified changes in the state of the environment, or carrying out measurements on the environment. Each task is a sequence of alternating computation and action phases. Computation phase activites include determination of the action to be carried out in the next phase, and recording of information on neighborhood environmental system states. Action phase activities include motion of the quantum robot and changes in the neighborhood environment system states. Models of quantum robots and their interactions with environments are described using discrete space and time. A unitary step operator T that gives the single time step dynamics is associated with each task. T=Ta+Tc is a sum of action phase and computation phase step operators. Conditions that Ta and Tc should satisfy are given along with a description of the evolution as a sum over paths of completed phase input and output states. A simple example of a task—carrying out a measurement on a very simple environment—is analyzed in detail. A decision tree for the task is presented and discussed in terms of the sums over phase paths. It is seen that no definite times or durations are associated with the phase steps in the tree, and that the tree describes the successive phase steps in each path in the sum over phase paths.

Paul Benioff

1998-08-01T23:59:59.000Z

420

Recently, a programmable quantum annealing machine has been built that minimizes the cost function of hard optimization problems by adiabatically quenching quantum fluctuations. Tests performed by different research teams have shown that, indeed, the machine seems to exploit quantum effects. However experiments on a class of random-bond instances have not yet demonstrated an advantage over classical optimization algorithms on traditional computer hardware. Here we present evidence as to why this might be the case. These engineered quantum annealing machines effectively operate coupled to a decohering thermal bath. Therefore, we study the finite-temperature critical behavior of the standard benchmark problem used to assess the computational capabilities of these complex machines. We simulate both random-bond Ising models and spin glasses with bimodal and Gaussian disorder on the D-Wave Chimera topology. Our results show that while the worst-case complexity of finding a ground state of an Ising spin glass on the Chimera graph is not polynomial, the finite-temperature phase space is likely rather simple: Spin glasses on Chimera have only a zero-temperature transition. This means that benchmarking optimization methods using spin glasses on the Chimera graph might not be the best benchmark problems to test quantum speedup. We propose alternative benchmarks by embedding potentially harder problems on the Chimera topology. Finally, we also study the (reentrant) disorder-temperature phase diagram of the random-bond Ising model on the Chimera graph and show that a finite-temperature ferromagnetic phase is stable up to 19.85(15)% antiferromagnetic bonds. Beyond this threshold the system only displays a zero-temperature spin-glass phase. Our results therefore show that a careful design of the hardware architecture and benchmark problems is key when building quantum annealing machines.

Helmut G. Katzgraber; Firas Hamze; Ruben S. Andrist

2014-04-11T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

421

Nanophotonic quantum phase switch with a single atom

In analogy to transistors in classical electronic circuits, a quantum optical switch is an important element of quantum circuits and quantum networks. Operated at the fundamental limit where a single quantum of light or matter controls another field or material system, it may enable fascinating applications such as long-distance quantum communication, distributed quantum information processing and metrology, and the exploration of novel quantum states of matter. Here, by strongly coupling a photon to a single atom trapped in the near field of a nanoscale photonic crystal cavity, we realize a system where a single atom switches the phase of a photon, and a single photon modifies the atom's phase. We experimentally demonstrate an atom-induced optical phase shift that is nonlinear at the two-photon level, a photon number router that separates individual photons and photon pairs into different output modes, and a single-photon switch where a single "gate" photon controls the propagation of a subsequent probe fiel...

Tiecke, T G; de Leon, N P; Liu, L R; Vuleti?, V; Lukin, M D

2014-01-01T23:59:59.000Z

422

Energy diffusion in strongly driven quantum chaotic systems

The energy evolution of a quantum chaotic system under the perturbation that harmonically depends on time is studied for the case of large perturbation, in which the rate of transition calculated from the Fermi golden rule exceeds the frequency of perturbation. It is shown that the energy evolution retains its diffusive character, with the diffusion coefficient that is asymptotically proportional to the magnitude of perturbation and to the square root of the density of states. The results are supported by numerical calculation. They imply the absence of the quantum-classical correspondence for the energy diffusion and the energy absorption in the classical limit $\\hbar \\to 0$.

P. V. Elyutin

2005-04-14T23:59:59.000Z

423

A local scheme accounting for EPR quantum correlations

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

2009-01-12T23:59:59.000Z

424

Quantum model of an autonomous oscillator in hard excitation regime

We propose the simple quantum model of nonlinear autonomous oscillator in hard excitation regime. We originate from classical equations of motion for similar oscillator and quantize them using the Lindblad master equation for the density matrix of this system. The solution for the populations of the stationary states of such oscillator may be explicitly found in the case when nonlinearity parameters of the problem are small. It was shown that in this situation there are three distinct regimes of behavior of the model. We compare properties of this model with corresponding ones of close open system, namely quantum oscillator in soft excitation regime. We discuss a possible applications of the results obtained.

E. D. Vol; M. A. Ialovega

2014-12-01T23:59:59.000Z

425

Spin transfer and coherence in coupled quantum wells

Science Journals Connector (OSTI)

Spin dynamics of optically excited electrons confined in asymmetric coupled quantum wells are investigated through time-resolved Faraday rotation experiments. The interwell coupling is shown to depend on applied electric field and barrier thickness. We observe three coupling regimes: independent spin precession in isolated quantum wells, incoherent spin transfer between single-well states, and coherent spin transfer in a highly coupled system. Relative values of the interwell tunneling time, the electron-spin lifetime, and the Larmor precession period appear to govern this behavior.

M. Poggio, G. M. Steeves, R. C. Myers, N. P. Stern, A. C. Gossard, and D. D. Awschalom

2004-09-16T23:59:59.000Z

426

Quantum-Secure Authentication with a Classical Key

Authentication provides the trust people need to engage in transactions. The advent of physical keys that are impossible to copy promises to revolutionize this field. Up to now, such keys have been verified by classical challenge-response protocols. Such protocols are in general susceptible to emulation attacks. Here we demonstrate Quantum-Secure Authentication ("QSA") of an unclonable classical physical key in a way that is inherently secure by virtue of quantum-physical principles. Our quantum-secure authentication operates in the limit of a large number of channels, represented by the more than thousand degrees of freedom of an optical wavefront shaped with a spatial light modulator. This allows us to reach quantum security with weak coherent pulses of light containing dozens of photons, too few for an adversary to determine their complex spatial shapes, thereby rigorously preventing emulation.

Sebastianus A. Goorden; Marcel Horstmann; Allard P. Mosk; Boris Škori?; Pepijn W. H. Pinkse

2014-06-03T23:59:59.000Z

427

Wigner separated the possible types of symmetries in quantum theory into those symmetries that are unitary and those that are antiunitary. Unitary symmetries have been well studied whereas antiunitary symmetries and the physical implications associated with time-reversal symmetry breaking have had little influence on quantum information science. Here we develop a quantum circuits version of time-reversal symmetry theory, classifying time-symmetric and time-asymmetric Hamiltonians and circuits in terms of their underlying network elements and geometric structures. These results reveal that many of the typical quantum circuit networks found across the field of quantum information science exhibit time-asymmetry. We then experimentally implement the most fundamental time-reversal asymmetric process, applying local gates in an otherwise time-symmetric circuit to induce time-reversal asymmetry and thereby achieve (i) directional biasing in the transition probability between basis states, (ii) the enhancement of and (iii) the suppression of these transport probabilities. Our results imply that the physical effect of time-symmetry breaking plays an essential role in coherent transport and its control represents an omnipresent yet essentially untapped resource in quantum transport science.

DaWei Lu; Jacob D. Biamonte; Jun Li; Hang Li; Tomi H. Johnson; Ville Bergholm; Mauro Faccin; Zoltán Zimborás; Raymond Laflamme; Jonathan Baugh; Seth Lloyd

2014-05-23T23:59:59.000Z

428

Turbocharging Quantum Tomography.

Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography su %7C ers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. We describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more e %7C ectively detect and characterize quantum noise using carefully tailored ensembles of input states.

Blume-Kohout, Robin J; Gamble, John King,; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael

2015-01-01T23:59:59.000Z

429

Synthesis of multi-qudit Hybrid and d-valued Quantum Logic Circuits by Decomposition

Recent research in generalizing quantum computation from 2-valued qudits to d-valued qudits has shown practical advantages for scaling up a quantum computer. A further generalization leads to quantum computing with hybrid qudits where two or more qudits have different finite dimensions. Advantages of hybrid and d-valued gates (circuits) and their physical realizations have been studied in detail by Muthukrishnan and Stroud (Physical Review A, 052309, 2000), Daboul et al. (J. Phys. A: Math. Gen. 36 2525-2536, 2003), and Bartlett et al (Physical Review A, Vol.65, 052316, 2002). In both cases, a quantum computation is performed when a unitary evolution operator, acting as a quantum logic gate, transforms the state of qudits in a quantum system. Unitary operators can be represented by square unitary matrices. If the system consists of a single qudit, then Tilma et al (J.Phys. A: Math. Gen. 35 (2002) 10467-10501) have shown that the unitary evolution matrix (gate) can be synthesized in terms of its Euler angle parameterization. However, if the quantum system consists of multiple qudits, then a gate may be synthesized by matrix decomposition techniques such as QR factorization and the Cosine-sine Decomposition (CSD). In this article, we present a CSD based synthesis method for n qudit hybrid quantum gates, and as a consequence, derive a CSD based synthesis method for n qudit gates where all the qudits have the same dimension.

Faisal Shah Khan; Marek Perkowski

2005-11-03T23:59:59.000Z

430

Nested Quantum Error Correction Codes

The theory of quantum error correction was established more than a decade ago as the primary tool for fighting decoherence in quantum information processing. Although great progress has already been made in this field, limited methods are available in constructing new quantum error correction codes from old codes. Here we exhibit a simple and general method to construct new quantum error correction codes by nesting certain quantum codes together. The problem of finding long quantum error correction codes is reduced to that of searching several short length quantum codes with certain properties. Our method works for all length and all distance codes, and is quite efficient to construct optimal or near optimal codes. Two main known methods in constructing new codes from old codes in quantum error-correction theory, the concatenating and pasting, can be understood in the framework of nested quantum error correction codes.

Zhuo Wang; Kai Sun; Hen Fan; Vlatko Vedral

2009-09-28T23:59:59.000Z

431

Response: Issue Numbers and Librarianship

Science Journals Connector (OSTI)

...some time. Put back the issue number. ALISON BAKER Librawy Jackson Laboratot), Bar...passage in which he supposes some unusually wise ape-like animal to have first thought...the approving nods and kindly grunts ofmy wise and most respected chief. And now I feel...

DANIEL E. KOSHLAND; JR.

1986-05-23T23:59:59.000Z

432

Approximation method for a spherical bound system in the quantum plasma

A system of quantum hydrodynamic equations has been used for investigating the dielectric tensor and dispersion equation of a semiconductor as a quantum magnetized plasma. Dispersion relations and their modifications due to quantum effects are derived for both longitudinal and transverse waves. The number of states and energy levels are analytically estimated for a spherical bound system embedded in a semiconductor quantum plasma. The results show that longitudinal waves decay rapidly and do not interact with the spherical bound system. The energy shifts caused by the spin-orbit interaction and the Zeeman effect are calculated.

Mehramiz, A.; Sobhanian, S. [Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, East Azerbaijan 51664 (Iran, Islamic Republic of); Mahmoodi, J. [Department of Physics, Faculty of Science, University of Qom, P.O. Box 3716146611, Qom (Iran, Islamic Republic of)

2010-08-15T23:59:59.000Z

433

Quantum graph as a quantum spectral filter

We study the transmission of a quantum particle along a straight input-output line to which a graph {Gamma} is attached at a point. In the point of contact we impose a singularity represented by a certain properly chosen scale-invariant coupling with a coupling parameter {alpha}. We show that the probability of transmission along the line as a function of the particle energy tends to the indicator function of the energy spectrum of {Gamma} as {alpha}{yields}{infinity}. This effect can be used for a spectral analysis of the given graph {Gamma}. Its applications include a control of a transmission along the line and spectral filtering. The result is illustrated with an example where {Gamma} is a loop exposed to a magnetic field. Two more quantum devices are designed using other special scale-invariant vertex couplings. They can serve as a band-stop filter and as a spectral separator, respectively.

Turek, Ondrej; Cheon, Taksu [Laboratory of Physics, Kochi University of Technology, Tosa Yamada, Kochi 782-8502 (Japan)] [Laboratory of Physics, Kochi University of Technology, Tosa Yamada, Kochi 782-8502 (Japan)

2013-03-15T23:59:59.000Z

434

Storage of hyperentanglement in a solid-state quantum memory

Two photons can simultaneously share entanglement between several degrees of freedom such as polarization, energy-time, spatial mode and orbital angular momentum. This resource is known as hyperentanglement, and it has been shown to be an important tool for optical quantum information processing. Here we demonstrate the quantum storage and retrieval of photonic hyperentanglement in a solid-state quantum memory. A pair of photons entangled in polarization and energy-time is generated such that one photon is stored in the quantum memory, while the other photon has a telecommunication wavelength suitable for transmission in optical fibre. We measured violations of a Clauser-Horne-Shimony-Holt (CHSH) Bell inequality for each degree of freedom, independently of the other one, which proves the successful storage and retrieval of the two bits of entanglement shared by the photons. Our scheme is compatible with long-distance quantum communication in optical fibre, and is in particular suitable for linear-optical entanglement purification for quantum repeaters.

Alexey Tiranov; Jonathan Lavoie; Alban Ferrier; Philippe Goldner; Varun B. Verma; Sae Woo Nam; Richard P. Mirin; Adriana E. Lita; Francesco Marsili; Harald Herrmann; Christine Silberhorn; Nicolas Gisin; Mikael Afzelius; Felix Bussieres

2014-12-19T23:59:59.000Z

435

Strong reactions in quantum super PDEs. III: Exotic quantum supergravity

Following the previous two parts, of a work devoted to encode strong reaction dynamics in the A. Pr\\'astaro's algebraic topology of quantum super PDE's, nonlinear quantum propagators in the observed quantum super Yang-Mills PDE, $\\hat{(YM)}[i]$, are further characterized. In particular, nonlinear quantum propagators with non-zero defect quantum electric-charge, are interpreted as {\\em exotic-quantum supergravity} effects. As an application, the recently discovered bound-state called $Zc(3900)$, is obtained as a neutral quasi-particle, generated in a $Q$-quantum exotic supergravity process. {\\em Quantum entanglement} is justified by means of the algebraic topologic structure of nonlinear quantum propagators. Quantum Cheshire cats are considered as examples of quantum entanglements. Existence theorem for solutions of $\\hat{(YM)}[i]$ admitting negative local temperatures ({\\em quantum thermodynamic-exotic solutions}) is obtained too and related to quantum entanglement. Such exotic solutions are used to encode Universe at the Planck-epoch. It is proved that the Universe's expansion at the Planck epoch is justified by the fact that it is encoded by a nonlinear quantum propagator having thermodynamic quantum exotic components in its boundary. This effect produces also an increasing of energy in the Universe at the Einstein epoch: {\\em Planck-epoch-legacy} on the boundary of our Universe. This is the main source of the Universe's expansion and solves the problem of the non-apparent energy-matter ({\\em dark-energy-matter}) in the actual Universe. Breit-Wheeler-type processes have been proved in the framework of the Pr\\'astaro's algebraic topology of quantum super Yang-Mills PDEs. Numerical comparisons of nonlinear quantum propagators with Weinberg-Salam electroweak theory in Standard Model are given.

Agostino Prástaro

2015-02-01T23:59:59.000Z

436

Conditional quantum optical processes enable a wide range of technologies from generation of highly non-classical states to implementation of quantum logic operations. The process fidelity that can be achieved in a realistic implementation depends on a number of system parameters. Here we experimentally examine Fock-state filtration, a canonical example of a broad class of conditional quantum operations acting on a single optical field mode. This operation is based upon interference of the mode to be manipulated with an auxiliary single-photon state at a beam splitter, resulting in the entanglement of the two output modes. A conditional projective measurement onto a single photon at one output mode heralds the success of the process. This operation, which implements a measurement-induced nonlinearity, is capable of suppressing particular photon-number probability amplitudes of an arbitrary quantum state. We employ coherent-state process tomography to determine the precise operation realized in our experiment. To identify the key sources of experimental imperfection, we develop a model of the process and identify three main contributions that significantly hamper its efficacy. The reconstructed tensor is compared with a model of the process taking into account sources of experimental imperfection with fidelity better than 0.95. This enables us to identify three key challenges to overcome in realizing a filter with high fidelity - namely the single-photon nature of the auxiliary state, high-mode overlap, and the need for number resolving detection when heralding. The results show that the filter does indeed exhibit a nonlinear response as a function of input photon number and preserves the phase relation between Fock layers of the output state, providing promise for future applications.

Merlin Cooper; Eirion Slade; Michal Karpinski; Brian J. Smith

2014-10-25T23:59:59.000Z

437

Quantum computation beyond the circuit model

The quantum circuit model is the most widely used model of quantum computation. It provides both a framework for formulating quantum algorithms and an architecture for the physical construction of quantum computers. However, ...

Jordan, Stephen Paul

2008-01-01T23:59:59.000Z

438

We identify a signature of quantum gravitational effects that survives from the early universe to the current era: Fluctuations of quantum fields as seen by comoving observers are significantly influenced by the history of the early universe. In particular we show how the existence (or not) of a quantum bounce leaves a trace in the background quantum noise that is not damped and would be non-negligible even nowadays. Furthermore, we estimate an upper bound for the typical energy and length scales where quantum effects are relevant. We discuss how this signature might be observed and therefore used to build falsifiability tests of quantum gravity theories.

Luis J. Garay; Mercedes Martin-Benito; Eduardo Martin-Martinez

2014-02-15T23:59:59.000Z

439

Computing Betti Numbers via Combinatorial Laplacians

Computing Betti Numbers via Combinatorial Laplacians method to compute Betti numbers of sim- plicial complexes. This has a number of advantages over are the Betti numbers, the i-th Betti number, bi= bi(X), being the rank of Hi(X). The Betti numbers often have

Friedman, Joel

440

An algorithm for minimization of quantum cost

A new algorithm for minimization of quantum cost of quantum circuits has been designed. The quantum cost of different quantum circuits of particular interest (eg. circuits for EPR, quantum teleportation, shor code and different quantum arithmetic operations) are computed by using the proposed algorithm. The quantum costs obtained using the proposed algorithm is compared with the existing results and it is found that the algorithm has produced minimum quantum cost in all cases.

Anindita Banerjee; Anirban Pathak

2009-10-12T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

441

Energy density matrix formalism for interacting quantum systems: a quantum Monte Carlo study

We develop an energy density matrix that parallels the one-body reduced density matrix (1RDM) for many-body quantum systems. Just as the density matrix gives access to the number density and occupation numbers, the energy density matrix yields the energy density and orbital occupation energies. The eigenvectors of the matrix provide a natural orbital partitioning of the energy density while the eigenvalues comprise a single particle energy spectrum obeying a total energy sum rule. For mean-field systems the energy density matrix recovers the exact spectrum. When correlation becomes important, the occupation energies resemble quasiparticle energies in some respects. We explore the occupation energy spectrum for the finite 3D homogeneous electron gas in the metallic regime and an isolated oxygen atom with ground state quantum Monte Carlo techniques imple- mented in the QMCPACK simulation code. The occupation energy spectrum for the homogeneous electron gas can be described by an effective mass below the Fermi level. Above the Fermi level evanescent behavior in the occupation energies is observed in similar fashion to the occupation numbers of the 1RDM. A direct comparison with total energy differences demonstrates a quantita- tive connection between the occupation energies and electron addition and removal energies for the electron gas. For the oxygen atom, the association between the ground state occupation energies and particle addition and removal energies becomes only qualitative. The energy density matrix provides a new avenue for describing energetics with quantum Monte Carlo methods which have traditionally been limited to total energies.

Krogel, Jaron T [ORNL] [ORNL; Kim, Jeongnim [ORNL] [ORNL; Reboredo, Fernando A [ORNL] [ORNL

2014-01-01T23:59:59.000Z

442

Exploiting locality in quantum computation for quantum chemistry

Accurate prediction of chemical and material properties from first principles quantum chemistry is a challenging task on traditional computers. Recent developments in quantum computation offer a route towards highly accurate solutions with polynomial cost, however this solution still carries a large overhead. In this perspective, we aim to bring together known results about the locality of physical interactions from quantum chemistry with ideas from quantum computation. We show that the utilization of spatial locality combined with the Bravyi-Kitaev transformation offers an improvement in the scaling of known quantum algorithms for quantum chemistry and provide numerical examples to help illustrate this point. We combine these developments to improve the outlook for the future of quantum chemistry on quantum computers.

Jarrod R. McClean; Ryan Babbush; Peter J. Love; Alán Aspuru-Guzik

2014-07-29T23:59:59.000Z

443

Quantum dynamics of elementary reactions in the gas phase and on surfaces

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

Quantum Quantum dynamics of elementary reactions in the gas phase and on surfaces Quantum Dynamics of Elementary Reactions in the Gas Phase and on Surfaces Key Challenges: This research addresses several important dynamics issues in elementary chemical reactions. One of the major obstacles in such studies is the quantum nature of the reactions, where the zero-point energy, mode selectivity, dynamical resonances, non-adiabatic transitions, and tunneling play an important role. The calculations are very challenging because of the large number of quantum states involved, and because of the large number of partial waves. The work required development of new methods and new, highly-efficient codes to calculate the total and state-resolved reaction probabilities. Numerically, the calculations are based on sparse

444

Quantum computing with atomic Josephson junction arrays

We present a quantum computing scheme with atomic Josephson junction arrays. The system consists of a small number of atoms with three internal states and trapped in a far-off-resonant optical lattice. Raman lasers provide the 'Josephson' tunneling, and the collision interaction between atoms represent the 'capacitive' couplings between the modes. The qubit states are collective states of the atoms with opposite persistent currents. This system is closely analogous to the superconducting flux qubit. Single-qubit quantum logic gates are performed by modulating the Raman couplings, while two-qubit gates result from a tunnel coupling between neighboring wells. Readout is achieved by tuning the Raman coupling adiabatically between the Josephson regime to the Rabi regime, followed by a detection of atoms in internal electronic states. Decoherence mechanisms are studied in detail promising a high ratio between the decoherence time and the gate operation time.

Tian Lin; Zoller, P. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria)

2003-10-01T23:59:59.000Z

445

Quantum Computing with Atomic Josephson Junction Arrays

We present a quantum computing scheme with atomic Josephson junction arrays. The system consists of a small number of atoms with three internal states and trapped in a far-off resonant optical lattice. Raman lasers provide the "Josephson" tunneling, and the collision interaction between atoms represent the "capacitive" couplings between the modes. The qubit states are collective states of the atoms with opposite persistent currents. This system is closely analogous to the superconducting flux qubit. Single qubit quantum logic gates are performed by modulating the Raman couplings, while two-qubit gates result from a tunnel coupling between neighboring wells. Readout is achieved by tuning the Raman coupling adiabatically between the Josephson regime to the Rabi regime, followed by a detection of atoms in internal electronic states. Decoherence mechanisms are studied in detail promising a high ratio between the decoherence time and the gate operation time.

Lin Tian; P. Zoller

2003-06-12T23:59:59.000Z

446

Cumulant expansion for studying damped quantum solitons

Science Journals Connector (OSTI)

The quantum statistics of damped optical solitons is studied using cumulant-expansion techniques. The effect of absorption is described in terms of ordinary Markovian relaxation theory, by coupling the optical field to a continuum of reservoir modes. After introduction of local bosonic field operators and spatial discretization, pseudo-Fokker-Planck equations for multidimensional s-parametrized phase-space functions are derived. These partial differential equations are equivalent to an infinite set of ordinary differential equations for the cumulants of the phase-space functions. Introducing an appropriate truncation condition, the resulting finite set of cumulant evolution equations can be solved numerically. Solutions are presented in a Gaussian approximation and the quantum noise is calculated, with special emphasis on squeezing and the recently measured spectral photon-number correlations [Spälter et al., Phys. Rev. Lett. 81, 786 (1998)].

Eduard Schmidt; Ludwig Knöll; Dirk-Gunnar Welsch

1999-03-01T23:59:59.000Z

447

Adiabatic Quantum Optimization for Associative Memory Recall

Hopfield networks are a variant of associative memory that recall information stored in the couplings of an Ising model. Stored memories are fixed points for the network dynamics that correspond to energetic minima of the spin state. We formulate the recall of memories stored in a Hopfield network using energy minimization by adiabatic quantum optimization (AQO). Numerical simulations of the quantum dynamics allow us to quantify the AQO recall accuracy with respect to the number of stored memories and the noise in the input key. We also investigate AQO performance with respect to how memories are stored in the Ising model using different learning rules. Our results indicate that AQO performance varies strongly with learning rule due to the changes in the energy landscape. Consequently, learning rules offer indirect methods for investigating change to the computational complexity of the recall task and the computational efficiency of AQO.

Hadayat Seddiqi; Travis S. Humble

2014-07-07T23:59:59.000Z

448

Individual quantum probes for optimal thermometry

The unknown temperature of a sample may be estimated with minimal disturbance by putting it in thermal contact with an individual quantum probe. If the interaction time is sufficiently long so that the probe thermalizes, the temperature can be read out directly from its steady state. Here we prove that the optimal quantum probe, acting as a thermometer with maximal thermal sensitivity, is an effective two-level atom with a maximally degenerate excited state. When the total interaction time is insufficient to produce full thermalization, we optimize the estimation protocol by breaking it down into sequential stages of probe preparation, thermal contact and measurement. We observe that frequently interrogated probes initialized in the ground state achieve the best performance. For both fully and partly thermalized thermometers, the sensitivity grows significantly with the number of levels, though optimization over their energy spectrum remains always crucial.

Luis A. Correa; Mohammad Mehboudi; Gerardo Adesso; Anna Sanpera

2014-11-23T23:59:59.000Z

449

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

Federal Procurement of Energy Efficient Products Federal Procurement of Energy Efficient Products RIN NUMBER: 1904-AB68 CLOSING DATE: August 20, 2007 COMMENT NUMBER DATE RECEIVED/ DATE OF LETTER NAME & TITLE OF COMMENTATOR AFFILIATION & ADDRESS OF COMMENTATOR 1 ? 7/31/07 Edwin Pinero Federal Environmental Executive Office of the Federal Environmental Executive 1200 Pennsylvania Avenue, NW Mail Code 1600J Washington, DC 20460 2 8/8/07 (e-mail) Bob Null President Arkansas Lamp Manufacturing bnull@arkansaslamp.com 3 8/10/07 (e-mail) Dawn Gunning Environmental Program Manager Department of Justice Dawn.M.Gunning@usdoj.gov 4 8/14/07 8/14/07 Kyle Pitsor Vice President, Government Relations National Electrical Manufacturers Association 1300 North 17th Street, Suite 1752 Rosslyn, VA 22209

450

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

RULEMAKING TITLE: Federal Procurement of Energy Efficient Products RULEMAKING TITLE: Federal Procurement of Energy Efficient Products RIN NUMBER: 1904-AB68 CLOSING DATE: August 20, 2007 COMMENT NUMBER DATE RECEIVED/ DATE OF LETTER NAME & TITLE OF COMMENTATOR AFFILIATION & ADDRESS OF COMMENTATOR 1 ? 7/31/07 Edwin Pinero Federal Environmental Executive Office of the Federal Environmental Executive 1200 Pennsylvania Avenue, NW Mail Code 1600J Washington, DC 20460 2 8/8/07 (e-mail) Bob Null President Arkansas Lamp Manufacturing bnull@arkansaslamp.com 3 8/10/07 (e-mail) Dawn Gunning Environmental Program Manager Department of Justice Dawn.M.Gunning@usdoj.gov 4 8/14/07 8/14/07 Kyle Pitsor Vice President, Government Relations National Electrical Manufacturers Association 1300 North 17th Street, Suite 1752

451

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

Document ID Number: Document ID Number: REV 3 NEPA REVIEW SCREENING FORM DOE/CX-00045 . J.proj(;l~t Titl~: - - - -- - - - - - - - - - - - - - - - - - -- --------- ------_. . _ - - - - - - - - - - - - - . - - - - - - - - - - - - - - - - - - - LIMITED FIREBREAK MAINTENANCE ON THE HANFORD SITE DURING CALENDAR YEAR 2012 II. Project Description and Location (including Time Period over which proposed action will occur and Project DimensionsÂ· e.g., acres displaced/disturbed, excavation length/depth, etc.): The Department of Energy (DOE) proposes to perform firebreak maintenance in selected areas of the Hanford Site during calendar year 2012 with limited use of physical, chemical, and prescribed burning methods. Prescribed burning will be performed by the Hanford Fire Department under approved burn plans and permits; and only in previously disturbed

452

Monitoring of ethylene by a pulsed quantum cascade laser

Monitoring of ethylene by a pulsed quantum cascade laser Damien Weidmann, Anatoliy A. Kosterev ethylene C2H4 concentrations by use of a rotational component of the fundamental 7 band. The laser.5960, 300.6320. 1. Introduction The detection of ethylene C2H4 at trace levels is important in a number

453

Quantum Cryptography Without Bell's Theorem and Without EPR

Quantum Cryptography Without Bell's Theorem and Without EPR Charles H. Bennett IBM Research Ekert has described how Einstein--Podolsky--Rosen (EPR) pairs can genÂ erate identical random numbers that Bell inequaliÂ ties are not needed for such an EPR procedure, point out that the non

CrÃ©peau, Claude

454

Optical implementability of the two-dimensional Quantum Walk

We propose an optical cavity implementation of the two-dimensional coined quantum walk on the line. The implementation makes use of only classical resources, and is tunable in the sense that a large number of different unitary transformations can be implemented by tuning some parameters of the device.

Eugenio Roldan; J. C. Soriano

2005-03-07T23:59:59.000Z

455

Robust quantum control using smooth pulses and topological winding

Powerful future technologies based on coherent quantum dynamical systems require an unprecedented level of control. Perhaps the greatest challenge in achieving such control is the decoherence induced by the environment, a problem which pervades experimental quantum physics and is particularly severe in the context of solid state quantum computing and nanoscale quantum devices because of the inherently strong coupling to the surrounding material. Recent years have seen rapid improvement in the quality of materials and in the design and fabrication of such systems, and it is crucial to match this progress with similar advances in the external control protocols used to manipulate quantum states so that the high levels of quantum coherence needed for technological applications persist despite the invariable presence of environmental noise. Here, we present an analytical approach that yields explicit constraints on the driving field which ensure that the leading-order noise-induced errors in a qubit's evolution cancel exactly. We derive constraints for two of the most common types of non-Markovian noise that arise in qubits: slow fluctuations of the qubit energy splitting and fluctuations in the driving field itself. By theoretically recasting a phase in the qubit's wavefunction as a topological winding number, we can satisfy the noise-cancelation conditions by adjusting driving field parameters without altering the target state or quantum evolution. We demonstrate our method by constructing robust quantum gates for two types of spin qubit: phosphorous donors in silicon and nitrogen-vacancy centers in diamond. Our results constitute an important step toward achieving robust generic control of quantum systems, bringing their novel applications closer to realization.

Edwin Barnes; Xin Wang; S. Das Sarma

2014-09-24T23:59:59.000Z

456

Quantum Algorithm for SAT Problem and Quantum Mutual Entropy

It is von Neumann who opened the window for today's Information epoch. He defined quantum entropy including Shannon's information more than 20 years ahead of Shannon, and he introduced a concept what computation means mathematically. In this paper I will report two works that we have recently done, one of which is on quantum algorithum in generalized sense solving the SAT problem (one of NP complete problems) and another is on quantum mutual entropy properly describing quantum communication processes.

Masanori Ohya

2004-06-29T23:59:59.000Z

457

Quantum Trajectories based on the Weak Value

The notion of trajectory of an individual particle is strictly inhibited in quantum mechanics because of the uncertainty principle. Nonetheless, the weak value, which has been proposed as a novel and measurable quantity definable to any quantum observable, can offer a possible description of trajectory on account of its statistical nature of the value. In this paper, we explore the physical significance provided by this weak trajectory by considering various situations where interference takes place simultaneously with the observation of particles, that is, in prototypical quantum situations for which no classical treatment is available. These include the double slit experiment and Lloyd's mirror, where in the former case it is argued that the real part of the weak trajectory describes an average over the possible classical trajectories involved in the process, and that the imaginary part is related to the variation of interference. It is shown that this average interpretation of the weak trajectory holds universally under the complex probability defined from the given transition process. These features remain essentially unaltered in the case of Lloyd's mirror where interference occurs with a single slit.

Takuya Mori; Izumi Tsutsui

2014-12-02T23:59:59.000Z

458

Large Scale Modular Quantum Computer Architecture with Atomic Memory and Photonic Interconnects

The practical construction of scalable quantum computer hardware capable of executing non-trivial quantum algorithms will require the juxtaposition of different types of quantum systems. We analyze a modular ion trap quantum computer architecture with a hierarchy of interactions that can scale to very large numbers of qubits. Local entangling quantum gates between qubit memories within a single register are accomplished using natural interactions between the qubits, and entanglement between separate registers is completed via a probabilistic photonic interface between qubits in different registers, even over large distances. We show that this architecture can be made fault-tolerant, and demonstrate its viability for fault-tolerant execution of modest size quantum circuits.

C. Monroe; R. Raussendorf; A. Ruthven; K. R. Brown; P. Maunz; L. -M. Duan; J. Kim

2013-07-02T23:59:59.000Z

459

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, Jörg; Liu, Ren-Bao

2014-01-01T23:59:59.000Z

460

Precision bounds in noisy quantum metrology

In an idealistic setting, quantum metrology protocols allow to sense physical parameters with mean squared error that scales as $1/N^2$ with the number of particles involved---substantially surpassing the $1/N$-scaling characteristic to classical statistics. A natural question arises, whether such an impressive enhancement persists when one takes into account the decoherence effects that are unavoidable in any real-life implementation. In this thesis, we resolve a major part of this issue by describing general techniques that allow to quantify the attainable precision in metrological schemes in the presence of uncorrelated noise. We show that the abstract geometrical structure of a quantum channel describing the noisy evolution of a single particle dictates then critical bounds on the ultimate quantum enhancement. Our results prove that an infinitesimal amount of noise is enough to restrict the precision to scale classically in the asymptotic $N$ limit, and thus constrain the maximal improvement to a constant factor. Although for low numbers of particles the decoherence may be ignored, for large $N$ the presence of noise heavily alters the form of both optimal states and measurements attaining the ultimate resolution. However, the established bounds are then typically achievable with use of techniques natural to current experiments. In this work, we thoroughly introduce the necessary concepts and mathematical tools lying behind metrological tasks, including both frequentist and Bayesian estimation theory frameworks. We provide examples of applications of the methods presented to typical qubit noise models, yet we also discuss in detail the phase estimation tasks in Mach-Zehnder interferometry both in the classical and quantum setting---with particular emphasis given to photonic losses while analysing the impact of decoherence.

Jan Kolodynski

2015-01-02T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

461

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

462

It is shown that weight operator of a composite quantum body in a weak external gravitational field in the post-Newtonian approximation of the General Relativity does not commute with its energy operator, taken in the absence of the field. Nevertheless, the weak equivalence between the expectations values of weight and energy is shown to survive at a macroscopic level for stationary quantum states for the simplest composite quantum body - a hydrogen atom. Breakdown of the weak equivalence between weight and energy at a microscopic level for stationary quantum states can be experimentally detected by studying unusual electromagnetic radiation, emitted by the atoms, supported and moved in the Earth gravitational field with constant velocity, using spacecraft or satellite. For superpositions of stationary quantum states, a breakdown of the above mentioned equivalence at a macroscopic level leads to time dependent oscillations of the expectation values of weight, where the equivalence restores after averaging over time procedure.

Andrei Lebed

2012-05-14T23:59:59.000Z

463

Heat Machines and Quantum Systems

Heat Machines and Quantum Systems: Towards the Third Law Thesis submitted for the degree of "Doctor Machines and Quantum Systems: Towards the Third Law Thesis submitted for the degree of "Doctor

Kosloff, Ronnie

464

Los Alamos researchers unravel the mystery of quantum dot blinking

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

Researchers unravel the mystery of quantum dot blinking Researchers unravel the mystery of quantum dot blinking Los Alamos researchers unravel the mystery of quantum dot blinking Most exciting is that the Los Alamos researchers have shown that blinking can be controlled and even completely suppressed electrochemically. November 9, 2011 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to plasma physics and new materials. Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy

465

Microscopic nonequilibrium theory of quantum well solar cells

Science Journals Connector (OSTI)

We present a microscopic theory of bipolar quantum well structures in the photovoltaic regime, based on the nonequilibrium Green’s function formalism for a multiband tight-binding Hamiltonian. The quantum kinetic equations for the single particle Green’s functions of electrons and holes are self-consistently coupled to Poisson’s equation, including intercarrier scattering on the Hartree level. Relaxation and broadening mechanisms are considered by the inclusion of acoustic and optical electron-phonon interaction in a self-consistent Born approximation of the scattering self-energies. Photogeneration of carriers is described on the same level in terms of a self-energy derived from the standard dipole approximation of the electron-photon interaction. Results from a simple two-band model are shown for the local density of states, spectral response, current spectrum, and current-voltage characteristics for generic single quantum well systems.

U. Aeberhard and R. H. Morf

2008-03-28T23:59:59.000Z

466

About the notion of truth in quantum mechanics

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

467

Quantum Money with Classical Verification

We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it.

Dmitry Gavinsky

2012-03-15T23:59:59.000Z

468

STOPPING TIMES IN QUANTUM MECHANICS

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

Attal, StÃ©phane

469

General Displaced SU (1,1) number states-revisited

The most general displaced number states, based on the bosonic and an irreducible representation(IREP) of the Lie algebra symmetry of su(1, 1) and associated to the Calogero-Sutherland model are introduced. Here, we utilize the Barut-Girardello displacement operator instead of the Klauder- Perelomov counterpart, to construct new kind of the displaced number states which can be classified in nonlinear coherent states regime, too, with special nonlinearity functions. They depend on two parameters, and can be converted into the well known Barut-Girardello coherent and number states respectively, depending on which of the parameters equal to zero. A discussion of the statistical properties of these states is included. Significant are their squeezing properties and anti bunching effects which can be raised by increasing the energy quantum number. Depending on the particular choice of the parameters of the above scenario, we are able to determine the status of compliance with flexible statistics. Major parts of the issue is spent on something that these states, in fact, should be considered as new kind of photon-added coherent states, too. Which can be reproduced through an iterated action of a creation operator on new nonlinear Barut-Girardello coherent states. Where the latter carry, also, outstanding statistical features.

A. Dehghani

2014-04-21T23:59:59.000Z

470

In 2001 all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single photon sources, linear optical elements, and single photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high efficiency single photon detectors, and low-loss interfacing of these components.

Jeremy L. O'Brien

2008-03-11T23:59:59.000Z

471

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical questions. This review presents quantum cosmology in a new picture that tries to incorporate the importance of inhomogeneity: De-emphasizing the traditional minisuperspace view, the dynamics is rather formulated in terms of the interplay of many interacting "microscopic" degrees of freedom that describe the space-time geometry. There is thus a close relationship with more-established systems in condensed-matter and particle physics even while the large set of space-time symmetries (general covariance) requires some adaptations and new developments. These extensions of standard methods are needed both at the fundamental level and at the stage of evaluating the theory by effective descriptions.

Bojowald, Martin

2015-01-01T23:59:59.000Z

472

We construct the invisible quantum barrier which represents the phenomenon of quantum reflection using the available data. We use the Abel equation to invert the data. The resulting invisible quantum barrier is double-valued in both axes. We study this invisible barrier in the case of atom and Bose-Einstein Condensate reflection from a solid silicon surface. A time-dependent, one-spatial dimension Gross-Pitaevskii equation is solved for the BEC case. We found that the BEC behaves very similarly to the single atom except for size effects, which manifest themselves in a maximum in the reflectivity at small distances from the wall. The effect of the atom-atom interaction on the BEC reflection and correspondingly on the invisible barrier is found to be appreciable at low velocities and comparable to the finite size effect. The trapping of ultracold atoms or BEC between two walls is discussed.

J. X. de Carvalho; M. S. Hussein; Weibin Li

2008-02-06T23:59:59.000Z

473

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

474

Extremal generalized quantum measurements

A measurement on a section K of the set of states of a finite dimensional C*-algebra is defined as an affine map from K to a probability simplex. Special cases of such sections are used in description of quantum networks, in particular quantum channels. Measurements on a section correspond to equivalence classes of so-called generalized POVMs, which are called quantum testers in the case of networks. We find extremality conditions for measurements on K and characterize generalized POVMs such that the corresponding measurement is extremal. These results are applied to the set of channels. We find explicit extremality conditions for two outcome measurements on qubit channels and give an example of an extremal qubit 1-tester such that the corresponding measurement is not extremal.

Anna Jencova

2012-07-23T23:59:59.000Z

475

Viscosity of Quantum Hall Fluids

Science Journals Connector (OSTI)

The viscosity of quantum fluids with an energy gap at zero temperature is related to the adiabatic curvature on the space parametrizing flat background metrics. For quantum Hall fluids on two-dimensional tori, the quantum viscosity is computed. It turns out to be isotropic, constant, and proportional to the magnetic field strength.

J. E. Avron; R. Seiler; P. G. Zograf

1995-07-24T23:59:59.000Z

476

Authentication of quantum messages.

Authentication is a well-studied area of classical cryptography: a sender A and a receiver B sharing a classical private key want to exchange a classical message with the guarantee that the message has not been modified or replaced by a dishonest party with control of the communication line. In this paper we study the authentication of messages composed of quantum states. We give a formal definition of authentication in the quantum setting. Assuming A and B have access to an insecure quantum channel and share a private, classical random key, we provide a non-interactive scheme that both enables A to encrypt and authenticate (with unconditional security) an m qubit message by encoding it into m + s qubits, where the probability decreases exponentially in the security parameter s. The scheme requires a private key of size 2m + O(s). To achieve this, we give a highly efficient protocol for testing the purity of shared EPR pairs. It has long been known that learning information about a general quantum state will necessarily disturb it. We refine this result to show that such a disturbance can be done with few side effects, allowing it to circumvent cryptographic protections. Consequently, any scheme to authenticate quantum messages must also encrypt them. In contrast, no such constraint exists classically: authentication and encryption are independent tasks, and one can authenticate a message while leaving it publicly readable. This reasoning has two important consequences: On one hand, it allows us to give a lower bound of 2m key bits for authenticating m qubits, which makes our protocol asymptotically optimal. On the other hand, we use it to show that digitally signing quantum states is impossible, even with only computational security.

Barnum, Howard; Crépeau, Jean-Claude; Gottesman, D. (Daniel); Smith, A. (Adam); Tapp, Alan

2001-01-01T23:59:59.000Z

477

Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma

We study the amplitude modulation of low-frequency, long-wavelength electrostatic drift-wave envelopes in a nonuniform quantum magnetoplasma consisting of cold ions and degenerate electrons. The effects of tunneling associated with the quantum Bohm potential and the Fermi pressure for nonrelativistic degenerate electrons, as well as the equilibrium density and magnetic field inhomogeneities are taken into account. Starting from a set of quantum magnetohydrodynamic equations, we derive a nonlinear Schrödinger equation (NLSE) that governs the dynamics of the modulated quantum drift-wave packets. The NLSE is used to study the modulational instability (MI) of a Stoke's wave train to a small plane wave perturbation. It is shown that the quantum tunneling effect as well as the scale length of inhomogeneity plays crucial roles for the MI of the drift-wave packets. Thus, the latter can propagate in the form of bright and dark envelope solitons or as drift-wave rogons in degenerate dense magnetoplasmas.

Misra, A. P., E-mail: apmisra@visva-bharati.ac.in, E-mail: apmisra@gmail.com [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235, West Bengal (India)

2014-04-15T23:59:59.000Z

478

Electric Field effects on quantum correlations in semiconductor quantum dots

We study the effect of external electric bias on the quantum correlations in the array of optically excited coupled semiconductor quantum dots. The correlations are characterized by the quantum discord and concurrence and are observed using excitonic qubits. We employ the lower bound of concurrence for thermal density matrix at different temperatures. The effect of the F\\"orster interaction on correlations will be studied. Our theoretical model detects nonvanishing quantum discord when the electric field is on while concurrence dies, ensuring the existence of nonclassical correlations as measured by the quantum discord.

S. Shojaei; M. Mahdian; R. Yousefjani

2012-05-01T23:59:59.000Z

479

No Drama Quantum Theory? A Review

Schr\\"{o}dinger (Nature, v.169, 538 (1952)) noted that the complex matter field in the Klein-Gordon equation can be made real by a gauge transform, although charged fields are believed to require complex functions. Surprisingly, the result can be extended to the Dirac equation: three complex components of the Dirac spinor function can be algebraically eliminated, and the remaining component can be made real by a gauge transform. Therefore, the Dirac equation is generally equivalent to one fourth-order partial differential equation for one real function (A. Akhmeteli, J. Math. Phys. v.52, 082303 (2011)). These results both belong in textbooks and can be used for development of new efficient methods of quantum chemistry. The matter field can be algebraically eliminated both in scalar electrodynamics and in spinor electrodynamics in a certain gauge. The resulting equations describe independent dynamics of the electromagnetic field, which permits mathematical simplification and can be useful for interpretation of quantum theory. For example, in the Bohm interpretation, the electromagnetic field can replace the wave function as the guiding field. It is also shown that for these equations, generalized Carleman embedding generates systems of linear equations in the Hilbert space, which look like second-quantized theories and are equivalent to the original nonlinear systems on the set of solutions of the latter. Thus, the relevant local realistic models can be embedded into quantum field theories. These models are equivalent to scalar electrodynamics and spinor electrodynamics, so they correctly describe a large body of experimental data. Although they may need some modifications for better agreement with experiments, they may be of great interest as "no drama quantum theories", as simple (in principle) as classical electrodynamics. Possible issues with the Bell theorem are discussed.

A. Akhmeteli

2011-11-20T23:59:59.000Z

480

The influence of the electron-exchange and quantum shielding on the bremsstrahlung spectrum is investigated in degenerate quantum plasmas. The impact-parameter analysis with the Shukla-Eliasson potential is applied to obtain the electron-ion bremsstrahlung radiation cross section as a function of the impact parameter, photon energy, projectile energy, electron-exchange parameter, Fermi energy, and plasmon energy. The result shows that the electron-exchange effect strongly enhances the bremsstrahlung radiation spectrum in degenerate quantum plasmas. It is also shown that the influence of the electron-exchange broadens the photon emission range in the electron-ion bremsstrahlung process. It is found that the electron-exchange effect focuses the bremsstrahlung photon energy in the soft photon domain. In addition, it is found that the bremsstrahlung radiation cross section increases with an increase of the Fermi energy and, however, decreases with increasing plasmon energy.

Jung, Young-Dae [Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407, USA and Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)] [Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407, USA and Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)

2013-10-15T23:59:59.000Z

While these samples are representative of the content of NLE

they are not comprehensive nor are they the most current set.

We encourage you to perform a real-time search of NLE

to obtain the most current and comprehensive results.

481

Quantum convolutional stabilizer codes

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

482

Thermodynamics of quantum lightspheres

Lightspheres, surfaces where massless particles are confined in closed orbits, are expected to be common astrophysical structures surrounding ultra-compact objects. In this paper a semi-classical treatment to photons in a lightspheres is proposed. We consider the quantum Maxwell field and derive its energy spectra. A thermodynamic approach for the quantum lightsphere is explored. Within this treatment, an expression for the spectral energy density of the emitted radiation is presented. Our results suggest that lightspheres populated by photons, when thermalized with their environment, have non-usual thermodynamic properties, which could lead to distinct observational signatures.

M. C. Baldiotti; Walace S. Elias; C. Molina; Thiago S. Pereira

2014-10-07T23:59:59.000Z

483

Thermodynamics of quantum lightspheres

Lightspheres, surfaces where massless particles are confined in closed orbits, are expected to be common astrophysical structures surrounding ultra-compact objects. In this paper a semi-classical treatment to photons in a lightspheres is proposed. We consider the quantum Maxwell field and derive its energy spectra. A thermodynamic approach for the quantum lightsphere is explored. Within this treatment, an expression for the spectral energy density of the emitted radiation is presented. Our results suggest that lightspheres populated by photons, when thermalized with their environment, have non-usual thermodynamic properties, which could lead to distinct observational signatures.

Baldiotti, M C; Molina, C; Pereira, Thiago S

2014-01-01T23:59:59.000Z

484

Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in quantum terms, of ``classical information.'' Various examples (some updating earlier work) are given of theorems which relate different incompatible kinds of information, and thus have no counterparts in classical information theory.

Robert B. Griffiths

2007-07-25T23:59:59.000Z

485

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 Bell’s, 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

486

Science Journals Connector (OSTI)

Quantum, in contrast to classical, information theory, allows for different incompatible types (or species) of information which cannot be combined with each other. Distinguishing these incompatible types is useful in understanding the role of the two classical bits in teleportation (or one bit in one-bit teleportation), for discussing decoherence in information-theoretic terms, and for giving a proper definition, in