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1

Quantum Field Theory and Representation Theory  

E-Print Network (OSTI)

Quantum Field Theory and Representation Theory Peter Woit woit@math.columbia.edu Department of Mathematics Columbia University Quantum Field Theory and Representation Theory ­ p.1 #12;Outline of the talk · Quantum Mechanics and Representation Theory: Some History Quantum Field Theory and Representation Theory

Woit, Peter

2

Quantum Field Theory Frank Wilczeky  

E-Print Network (OSTI)

Quantum Field Theory Frank Wilczeky Institute for Advanced Study, School of Natural Science, Olden Lane, Princeton, NJ 08540 I discuss the general principles underlying quantum eld theory, and attempt achieved and prospective. Possible limitations of quantum eld theory are viewed in the light of its history

Wilczek, Frank

3

Comprehending Quantum Theory from Quantum Fields  

E-Print Network (OSTI)

At the primary level of reality as described by quantum field theory, a fundamental particle like an electron represents a stable, discrete, propagating excited state of its underlying quantum field. QFT also tells us that the lowest vacuum state as well as the excited states of such a field is always very active with spontaneous, unpredictable quantum fluctuations. Also an underlying quantum field is known to be indestructible and immutable possessing the same value in each element of spacetime comprising the universe. These characteristics of the primary quantum fields together with the fact that the quantum fluctuations can be cogently substantiated to be quantum coherent throughout the universe provide a possible ontology of the quantum theory. In this picture, the wave function of a quantum particle represents the reality of the inherent quantum fluctuations at the core of the universe and endows the particle its counter intuitive quantum behavior.

Mani Bhaumik

2013-10-04T23:59:59.000Z

4

Quantum Algorithms for Quantum Field Theories  

E-Print Network (OSTI)

Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We develop a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (phi-fourth theory) in spacetime of four and fewer dimensions. Its run time is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. In the strong-coupling and high-precision regimes, our quantum algorithm achieves exponential speedup over the fastest known classical algorithm.

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

2011-11-15T23:59:59.000Z

5

Quantum Algorithms for Quantum Field Theories  

E-Print Network (OSTI)

Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We develop a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (phi-fourth theory) in spacetime of four and fewer dimensions. Its run time is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. In the strong-coupling and high-precision regimes, our quantum algorithm achieves exponential speedup over the fastest known classical algorithm.

Jordan, Stephen P; Preskill, John

2011-01-01T23:59:59.000Z

6

Quantum Field Theory in Graphene  

E-Print Network (OSTI)

This is a short non-technical introduction to applications of the Quantum Field Theory methods to graphene. We derive the Dirac model from the tight binding model and describe calculations of the polarization operator (conductivity). Later on, we use this quantity to describe the Quantum Hall Effect, light absorption by graphene, the Faraday effect, and the Casimir interaction.

Fialkovsky, I V

2011-01-01T23:59:59.000Z

7

Quantum Field Theory in Graphene  

E-Print Network (OSTI)

This is a short non-technical introduction to applications of the Quantum Field Theory methods to graphene. We derive the Dirac model from the tight binding model and describe calculations of the polarization operator (conductivity). Later on, we use this quantity to describe the Quantum Hall Effect, light absorption by graphene, the Faraday effect, and the Casimir interaction.

I. V. Fialkovsky; D. V. Vassilevich

2011-11-13T23:59:59.000Z

8

Quantum field theory without divergences  

E-Print Network (OSTI)

It is shown that loop divergences emerging in the Green functions in quantum field theory originate from correspondence of the Green functions to {\\em unmeasurable} (and hence unphysical) quantities. This is because no physical quantity can be measured in a point, but in a region, the size of which is constrained by the resolution of measuring equipment. The incorporation of the resolution into the definition of quantum fields $\\phi(x)\\to\\phi^{(A)}(x)$ and appropriate change of Feynman rules results in finite values of the Green functions. The Euclidean $\\phi^4$-field theory is taken as an example.

Altaisky, M V

2010-01-01T23:59:59.000Z

9

Quantum field theory without divergences  

E-Print Network (OSTI)

It is shown that loop divergences emerging in the Green functions in quantum field theory originate from correspondence of the Green functions to {\\em unmeasurable} (and hence unphysical) quantities. This is because no physical quantity can be measured in a point, but in a region, the size of which is constrained by the resolution of measuring equipment. The incorporation of the resolution into the definition of quantum fields $\\phi(x)\\to\\phi^{(A)}(x)$ and appropriate change of Feynman rules results in finite values of the Green functions. The Euclidean $\\phi^4$-field theory is taken as an example.

M. V. Altaisky

2010-02-12T23:59:59.000Z

10

Spaces of Quantum Field Theories  

E-Print Network (OSTI)

The concept of a "space of quantum field theories" or "theory space" was set out in the 1970's in work of Wilson, Friedan and others. This structure should play an important role in organizing and classifying QFTs, and in the study of the string landscape, allowing us to say when two theories are connected by finite variations of the couplings or by RG flows, when a sequence of QFTs converges to another QFT, and bounding the amount of information needed to uniquely specify a QFT, enabling us to estimate their number. As yet we do not have any definition of theory space which can be used to make such arguments. In this talk, we will describe various concepts and tools which should be developed for this purpose, inspired by the analogous mathematical problem of studying the space of Riemannian manifolds. We state two general conjectures about the space of two-dimensional conformal field theories, and we define a distance function on this space, which gives a distance between any pair of theories, whether or not they are connected by varying moduli. Based on talks given at QTS6 (University of Kentucky), Erice, Texas A& M, and Northwestern University. To appear in the proceedings of QTS6.

Michael R. Douglas

2010-05-16T23:59:59.000Z

11

Spinless Quantum Field Theory and Interpretation  

E-Print Network (OSTI)

Quantum field theory is mostly known as the most advanced and well-developed theory in physics, which combines quantum mechanics and special relativity consistently. In this work, we study the spinless quantum field theory, namely the Klein-Gordon equation, and we find that there exists a Dirac form of this equation which predicts the existence of spinless fermion. For its understanding, we start from the interpretation of quantum field based on the concept of quantum scope, we also extract new meanings of wave-particle duality and quantum statistics. The existence of spinless fermion is consistent with spin-statistics theorem and also supersymmetry, and it leads to several new kinds of interactions among elementary particles. Our work contributes to the study of spinless quantum field theory and could have implications for the case of higher spin.

Dong-Sheng Wang

2013-03-07T23:59:59.000Z

12

Numerical Object Oriented Quantum Field Theory Calculations  

E-Print Network (OSTI)

The qft++ package is a library of C++ classes that facilitate numerical (not algebraic) quantum field theory calculations. Mathematical objects such as matrices, tensors, Dirac spinors, polarization and orbital angular momentum tensors, etc. are represented as C++ objects in qft++. The package permits construction of code which closely resembles quantum field theory expressions, allowing for quick and reliable calculations.

M. Williams

2008-05-19T23:59:59.000Z

13

Mathematical Quantum Field Theory and Renormalization Theory  

E-Print Network (OSTI)

This volume of Math-for-Industry Lecture Note Series is dedicated to Professor Izumi Ojima and Professor Kei-ichi Ito on the occasion of their sixtieth birthdays. Professor Izumi Ojima and Professor Kei-ichi Ito have organized a lot of interesting and advanced conferences, e.g., RIMS conference, on quantum field theory and related topics, and they have encouraged not only young but also senior scientists. We would like to express our hearty gratitude to Professor Izumi Ojima and Professor Kei-ichi Ito for their continuous encouragement to us, stimulating our works, innumerable, unbounded helpful comments to our scientific researches. This lecture note is collecting several research papers and survey articles contributed by invited speakers of the international conference

Renormalization

2009-01-01T23:59:59.000Z

14

Quantum field theories on the Lefschetz thimble  

E-Print Network (OSTI)

In these proceedings, we summarize the Lefschetz thimble approach to the sign problem of Quantum Field Theories. In particular, we review its motivations, and we summarize the results of the application of two different algorithms to two test models.

M. Cristoforetti; F. Di Renzo; A. Mukherjee; L. Scorzato

2013-12-04T23:59:59.000Z

15

Neutrix Calculus and Finite Quantum Field Theory  

E-Print Network (OSTI)

In general, quantum field theories (QFT) require regularizations and infinite renormalizations due to ultraviolet divergences in their loop calculations. Furthermore, perturbation series in theories like QED are not convergent series, but are asymptotic series. We apply neutrix calculus, developed in connection with asymptotic series and divergent integrals, to QFT,obtaining finite renormalizations. While none of the physically measurable results in renormalizable QFT is changed, quantum gravity is rendered more manageable in the neutrix framework.

Y. Jack Ng; H. van Dam

2004-10-28T23:59:59.000Z

16

Continuous Wavelet Transform in Quantum Field Theory  

E-Print Network (OSTI)

We describe the application of the continuous wavelet transform to calculation of the Green functions in quantum field theory: scalar $\\phi^4$ theory, quantum electrodynamics, quantum chromodynamics. The method of continuous wavelet transform in quantum field theory presented in M.Altaisky Phys. Rev. D81(2010)125003 for the scalar $\\phi^4$ theory, consists in substitution of the local fields $\\phi(x)$ by those dependent on both the position $x$ and the resolution $a$. The substitution of the action $S[\\phi(x)]$ by the action $S[\\phi_a(x)]$ makes the local theory into nonlocal one, and implies the causality conditions related to the scale $a$, the region causality C. Christensen and L. Crane, J.Math. Phys 46 (2005) 122502. These conditions make the Green functions $G(x_1,a_1,..., x_n,a_n)= $ finite for any given set of regions by means of an effective cutoff scale $A=\\min (a_1,...,a_n)$.

Altaisky, Mikhail V

2013-01-01T23:59:59.000Z

17

Scalar Quantum Field Theory in Disordered Media  

E-Print Network (OSTI)

A free massive scalar field in inhomogeneous random media is investigated. The coefficients of the Klein-Gordon equation are taken to be random functions of the spatial coordinates. The case of an annealed-like disordered medium, modeled by centered stationary and Gaussian processes, is analyzed. After performing the averages over the random functions, we obtain the two-point causal Green's function of the model up to one-loop. The disordered scalar quantum field theory becomes qualitatively similar to a $\\lambda\\phi^{4}$ self-interacting theory with a frequency-dependent coupling.

Arias, E; Krein, G; Menezes, G; Svaiter, N F

2011-01-01T23:59:59.000Z

18

NUCLEAR SLAB COLLISION IN A RELATIVISTIC QUANTUM FIELD THEORY  

E-Print Network (OSTI)

Energy under Contract W-7405-ENG-43 LBL-12893 NUCLEAR SLAB COLLISION IN A RELATIVISTIC QUANTUM FIELD THEORY

Muller, K.-H.

2010-01-01T23:59:59.000Z

19

Duality in quantum field theory (and string theory)  

Science Conference Proceedings (OSTI)

These lectures give an introduction to duality in Quantum Field Theory. We discuss the phases of gauge theories and the implications of the electric-magnetic duality transformation to describe the mechanism of confinement. We review the exact results of N=1 supersymmetric QCD and the Seiberg-Witten solution of N=2 super Yang-Mills. Some of its extensions to String Theory are also briefly discussed.

Luis lvarez-Gaum; Frederic Zamora

1998-01-01T23:59:59.000Z

20

The effective field theory treatment of quantum gravity  

SciTech Connect

This is a pedagogical introduction to the treatment of quantum general relativity as an effective field theory. It starts with an overview of the methods of effective field theory and includes an explicit example. Quantum general relativity matches this framework and I discuss gravitational examples as well as the limits of the effective field theory. I also discuss the insights from effective field theory on the gravitational effects on running couplings in the perturbative regime.

Donoghue, John F. [Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States)

2012-09-24T23:59:59.000Z

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


21

Quantum gravity as a group field theory: a sketch  

E-Print Network (OSTI)

We give a very brief introduction to the group field theory approach to quantum gravity, a generalisation of matrix models for 2-dimensional quantum gravity to higher dimension, that has emerged recently from research in spin foam models.

Daniele Oriti

2005-12-07T23:59:59.000Z

22

Energy Inequalities in Quantum Field Theory  

E-Print Network (OSTI)

Quantum fields are known to violate all the pointwise energy conditions of classical general relativity. We review the subject of quantum energy inequalities: lower bounds satisfied by weighted averages of the stress-energy tensor, which may be regarded as the vestiges of the classical energy conditions after quantisation. Contact is also made with thermodynamics and related issues in quantum mechanics, where such inequalities find analogues in sharp Gaarding inequalities.

Christopher J. Fewster

2005-01-31T23:59:59.000Z

23

An application of neutrix calculus to quantum field theory  

E-Print Network (OSTI)

Neutrices are additive groups of negligible functions that do not contain any constants except 0. Their calculus was developed by van der Corput and Hadamard in connection with asymptotic series and divergent integrals. We apply neutrix calculus to quantum field theory, obtaining finite renormalizations in the loop calculations. For renormalizable quantum field theories, we recover all the usual physically observable results. One possible advantage of the neutrix framework is that effective field theories can be accommodated. Quantum gravity theories appear to be more manageable.

Y. Jack Ng; H. van Dam

2005-02-17T23:59:59.000Z

24

Quantum Mind from a Classical Field Theory of the Brain  

E-Print Network (OSTI)

We suggest that, with regard to a theory of quantum mind, brain processes can be described by a classical, dissipative, non-abelian gauge theory. In fact, such a theory has a hidden quantum nature due to its non-abelian character, which is revealed through dissipation, when the theory reduces to a quantum vacuum, where temperatures are of the order of absolute zero, and coherence of quantum states is preserved. We consider in particular the case of pure SU(2) gauge theory with a special anzatz for the gauge field, which breaks Lorentz invariance. In the ansatz, a contraction mapping plays the role of dissipation. In the limit of maximal dissipation, which corresponds to the attractive fixed point of the contraction mapping, the gauge fields reduce, up to constant factors, to the Pauli quantum gates for one-qubit states. Then tubuline-qubits can be processed in the quantum vacuum of the classical field theory of the brain, where decoherence is avoided due to the extremely low temperature. Finally, we interpret the classical SU(2) dissipative gauge theory as the quantum metalanguage (relative to the quantum logic of qubits), which holds the non-algorithmic aspect of the mind.

Paola Zizzi

2011-04-13T23:59:59.000Z

25

Quantum-field theories as representations of a single $^\\ast$-algebra  

E-Print Network (OSTI)

We show that many well-known quantum field theories emerge as representations of a single $^\\ast$-algebra. These include free quantum field theories in flat and curved space-times, lattice quantum field theories, Wightman quantum field theories, and string theories. We prove that such theories can be approximated on lattices, and we give a rigorous definition of the continuum limit of lattice quantum field theories.

Andreas Raab

2013-02-17T23:59:59.000Z

26

Perturbative Aspects of Low-Dimensional Quantum Field Theory  

SciTech Connect

We investigate the low-dimensional applications of Quantum Field Theory (QFT), namely Chern-Simons-Witten Theory (CSWT) and Affine Toda Field Theory (ATFT) in 3- and 2- dimensions. We discuss the perturbative aspects of both theories and compare the results to the exact solutions obtained nonperturbatively. For the three dimensions CSWT case, the perturbative term agree with the nonperturbative polynomial invariants up to third order of the coupling constant 1/k. In the two dimensions ATFT, we investigate the perturbative aspect of S-matrices for A{sub 1}{sup (1)} case in eighth order of the coupling constant {beta}.

Wardaya, Asep Y. [Department of Physics, Diponegoro University, Jl. Prof. Soedarto SH, Semarang (Indonesia); Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, FMIPA, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132 (Indonesia); Zen, Freddy P.; Kosasih, Jusak S.; , Triyanta; Hartanto, Andreas [Indonesia Center for Theoretical and Mathematical Physics (ICTMP) (Indonesia); Theoretical Physics Laboratory, Theoretical High Energy Physics and Instrumentation Research Group, FMIPA, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132 (Indonesia)

2010-06-22T23:59:59.000Z

27

Almost zero-dimensional PT-symmetric quantum field theories  

E-Print Network (OSTI)

In 1992 Bender, Boettcher, and Lipatov proposed in two papers a new and unusual nonperturbative calculational tool in quantum field theory. The objective was to expand the Green's functions of the quantum field theory as Taylor series in powers of the space-time dimension D. In particular, the vacuum energy for a massless \\phi^{2N} (N=1,2,3,...) quantum field theory was studied. The first two Taylor coefficients in this dimensional expansion were calculated {\\it exactly} and a set of graphical rules were devised that could be used to calculate approximately the higher coefficients in the series. This approach is mathematically valid and gives accurate results, but it has not been actively pursued and investigated. Subsequently, in 1998 Bender and Boettcher discovered that PT-symmetric quantum-mechanical Hamiltonians of the form H=p^2+x^2(ix)^\\epsilon, where \\epsilon\\geq0, have real spectra. These new kinds of complex non-Dirac-Hermitian Hamiltonians define physically acceptable quantum-mechanical theories. Th...

Bender, Carl M

2010-01-01T23:59:59.000Z

28

On quantum field theory with invariant parameter  

Science Conference Proceedings (OSTI)

1/2 particles, except for the so far unobserved Higgs boson, we first have to show that a viable formulation of Dirac theory within PRQT exists; this is especially...

29

Feynman Equation in Hamiltonian Quantum Field Theory  

E-Print Network (OSTI)

Functional Schr\\"{o}dinger equations for interacting fields are solved via rigorous non-perturbative Feynman type integrals.

Alexander Dynin

2000-05-26T23:59:59.000Z

30

Test Functions Space in Noncommutative Quantum Field Theory  

E-Print Network (OSTI)

It is proven that the $\\star$-product of field operators implies that the space of test functions in the Wightman approach to noncommutative quantum field theory is one of the Gel'fand-Shilov spaces $S^{\\beta}$ with $\\beta test functions smears the noncommutative Wightman functions, which are in this case generalized distributions, sometimes called hyperfunctions. The existence and determination of the class of the test function spaces in NC QFT is important for any rigorous treatment in the Wightman approach.

M. Chaichian; M. Mnatsakanova; A. Tureanu; Yu. Vernov

2007-06-12T23:59:59.000Z

31

Quantum Field Theory Is Not Merely Quantum Mechanics Applied to Low Energy Effective Degrees of Freedom  

E-Print Network (OSTI)

It is commonly assumed that quantum field theory arises by applying ordinary quantum mechanics to the low energy effective degrees of freedom of a more fundamental theory defined at ultra-high-energy/short-wavelength scales. We shall argue here that, even for free quantum fields, there are holistic aspects of quantum field theory that cannot be properly understood in this manner. Specifically, the ``subtractions'' needed to define nonlinear polynomial functions of a free quantum field in curved spacetime are quite simple and natural from the quantum field theoretic point of view, but are at best extremely ad hoc and unnatural if viewed as independent renormalizations of individual modes of the field. We illustrate this point by contrasting the analysis of the Casimir effect, the renormalization of the stress-energy tensor in time-dependent spacetimes, and anomalies from the point of quantum field theory and from the point of view of quantum mechanics applied to the independent low energy modes of the field. Some implications for the cosmological constant problem are discussed.

Stefan Hollands; Robert M. Wald

2004-05-16T23:59:59.000Z

32

Towards a quantum field theory of primitive string fields  

Science Conference Proceedings (OSTI)

We denote generating functions of massless even higher-spin fields 'primitive string fields' (PSF's). In an introduction we present the necessary definitions and derive propagators and currents of these PDF's on flat space. Their off-shell cubic interaction can be derived after all off-shell cubic interactions of triplets of higher-spin fields have become known. Then we discuss four-point functions of any quartet of PSF's. In subsequent sections we exploit the fact that higher-spin field theories in AdS{sub d+1} are determined by AdS/CFT correspondence from universality classes of critical systems in d-dimensional flat spaces. The O(N) invariant sectors of the O(N) vector models for 1 {=} 4, they are distinguished by their anomalous dimensions (in CFT{sub 3}) or by theirmass (in AdS{sub 4}). We sum over these multiplets and the spins to obtain 'string type fields', one for each such monomial.

Ruehl, W., E-mail: wue_ruehl@t-online.de [Technical University of Kaiserslautern, Department of Physics (Germany)

2012-10-15T23:59:59.000Z

33

A relativistically covariant version of Bohm's quantum field theory for the scalar field  

E-Print Network (OSTI)

We give a relativistically covariant, wave-functional formulation of Bohm's quantum field theory for the scalar field based on a general foliation of space-time by space-like hypersurfaces. The wave functional, which guides the evolution of the field, is space-time-foliation independent but the field itself is not. Hence, in order to have a theory in which the field may be considered a beable, some extra rule must be given to determine the foliation. We suggest one such rule based on the eigen vectors of the energy-momentum tensor of the field itself.

George Horton; Chris Dewdney

2004-07-13T23:59:59.000Z

34

Green function identities in Euclidean quantum field theory  

E-Print Network (OSTI)

Given a generic Lagrangian system of even and odd fields, we show that any infinitesimal transformation of its classical Lagrangian yields the identities which Euclidean Green functions of quantum fields satisfy.

G. Sardanashvily

2006-04-01T23:59:59.000Z

35

Generalizing the ADM Computation to Quantum Field Theory  

E-Print Network (OSTI)

The absence of recognizable, low energy quantum gravitational effects requires that some asymptotic series expansion be wonderfully accurate, but the correct expansion might involve logarithms or fractional powers of Newton's constant. That would explain why conventional perturbation theory shows uncontrollable ultraviolet divergences. We explore this possibility in the context of the mass of a charged, gravitating scalar. The classical limit of this system was solved exactly in 1960 by Arnowitt, Deser and Misner, and their solution does exhibit nonanalytic dependence on Newton's constant. We derive an exact functional integral representation for the mass of the quantum field theoretic system, and then develop an alternate expansion for it based on a correct implementation of the method of stationary phase. The new expansion entails adding an infinite class of new diagrams to each order and subtracting them from higher orders. The zeroth order term of the new expansion has the physical interpretation of a first quantized Klein-Gordon scalar which forms a bound state in the gravitational and electromagnetic potentials sourced by its own probability current. We show that such bound states exist and we obtain numerical results for their masses.

P. J. Mora; N. C. Tsamis; R. P. Woodard

2011-08-22T23:59:59.000Z

36

Vacuum Energy Problem, Fundamental Length and Deformed Quantum Field Theory  

E-Print Network (OSTI)

The cosmological constant (vacuum energy) problem is analyzed within the scope of quantum theories with UV-cut-off or fundamental length. Various cases associated with the appearance of the latter are considered both using the Generalized Uncertainty Relations and the deformed density matrix,previously introduced in the author's works. The use of the deformed density matrix is examined in detail. It is demonstrated that, provided the Fischler-Susskind cosmic holographic conjecture is valid, the Vacuum Energy Density takes a value close to the experimental one. The arguments supporting the validity of this conjecture are given on the basis of the recently obtained results on Gravitational Holography.

A. E. Shalyt-Margolin

2007-12-19T23:59:59.000Z

37

Time-to-space conversion in quantum field theory of flavor mixing  

E-Print Network (OSTI)

We consider the problem of time-to-space conversion in quantum field theory of flavor mixing using a generalization of the wave-packet method in quantum mechanics. We work entirely within the canonical formalism of creation and annihilation operators that allows us, unlike the usual wave-packet formulation, to include the nontrivial effect due to flavor condensation in the vacuum.

Chueng-Ryong Ji; Yuriy Mishchenko

2004-03-07T23:59:59.000Z

38

Pascual Jordan's legacy and the ongoing research in quantum field theory  

E-Print Network (OSTI)

Pascual Jordan's path-breaking role as the protagonist of quantum field theory (QFT) is recalled and his friendly dispute with Dirac's particle-based relativistic quantum theory is presented as the start of the field-particle conundrum which, though in modified form, persists up to this date. Jordan had an intuitive understanding that the existence of a causal propagation with finite propagation speed in a quantum theory led to radically different physical phenomena than those of QM. The conceptional-mathematical understanding for such an approach began to emerge only 30 years later. The strongest link between Jordan's view of QFT and modern "local quantum physics" is the central role of causal locality as the defining principle of QFT as opposed to the Born localization in QM. The issue of causal localization is also the arena where misunderstandings led to a serious derailment of large part of particle theory e.g. the misinterpretation of an infinite component pointlike field resulting from the quantization of the Nambu-Goto Lagrangian as a spacetime quantum string. The new concept of modular localization, which replaces Jordan's causal locality, is especially important to overcome the imperfections of gauge theories for which Jordan was the first to note nonlocal aspects of physical (not Lagrangian) charged fields. Two interesting subjects in which Jordan was far ahead of his contemporaries will be presented in two separate sections.

Bert Schroer

2010-10-21T23:59:59.000Z

39

On triviality of $\\lambda\\phi^4$ quantum field theory in four dimensions  

E-Print Network (OSTI)

Interacting quantum scalar field theories in $dS_D\\times M_d$ spacetime can be reduced to Euclidean field theories in $M_d$ space in the vicinity of $I_+$ infinity of $dS_D$ spacetime. Using this non-perturbative mapping, we analyze the critical behavior of Euclidean $\\lambda\\phi_4^4$ theory in the symmetric phase and find the asymptotic behavior $\\beta(\\lambda)\\sim \\lambda$ of the beta function at strong coupling. Scaling violating contributions to the beta function are also estimated in this regime.

Podolsky, Dmitry I

2010-01-01T23:59:59.000Z

40

Double-Scaling Limit of a Broken Symmetry Quantum Field Theory  

E-Print Network (OSTI)

The Ising limit of a conventional Hermitian parity-symmetric scalar quantum field theory is a correlated limit in which two bare Lagrangian parameters, the coupling constant $g$ and the {\\it negative} mass squared $-m^2$, both approach infinity with the ratio $-m^2/g=\\alpha>0$ held fixed. In this limit the renormalized mass of the asymptotic theory is finite. Moreover, the limiting theory exhibits universal properties. For a non-Hermitian $\\cal PT$-symmetric Lagrangian lacking parity symmetry, whose interaction term has the form $-g(i\\phi)^N/N$, the renormalized mass diverges in this correlated limit. Nevertheless, the asymptotic theory still has interesting properties. For example, the one-point Green's function approaches the value $-i\\alpha^{1/(N-2)}$ independently of the space-time dimension $D$ for $D<2$. Moreover, while the Ising limit of a parity-symmetric quantum field theory is dominated by a dilute instanton gas, the corresponding correlated limit of a $\\cal PT$-symmetric quantum field theory wit...

Bender, C M; Jones, H F; Meisinger, P N; Bender, Carl M.; Boettcher, Stefan; Meisinger, Peter N.

2001-01-01T23:59:59.000Z

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


41

1 String field theory  

E-Print Network (OSTI)

This elementary introduction to string field theory highlights the features and the limitations of this approach to quantum gravity as it is currently understood. String field theory is a formulation of string theory as a field theory in space-time with an infinite number of massive fields. Although existing constructions of string field theory require expanding around a fixed choice of space-time background, the theory is in principle background-independent, in the sense that different backgrounds can be realized as different field configurations in the theory. String field theory is the only string formalism developed so far which, in principle, has the potential to systematically address questions involving multiple asymptotically distinct string backgrounds. Thus, although it is not yet well defined as a quantum theory, string field theory may eventually be helpful for understanding questions related to cosmology in string theory. 1.1

W. Taylor

2006-01-01T23:59:59.000Z

42

Model Theory and Quantum  

E-Print Network (OSTI)

Model Theory and Quantum Groups Sonia L'Innocente Model Theory and Quantum Groups Sonia L'Innocente (University of Mons) Model Theory and Quantum Groups 1 / 40 #12;Model Theory and Quantum Groups Sonia L quantum plane, submitted. This work is inspired by Ivo Herzog's paper: The pseudo-finite dimensional

Mons-Hainaut, Université de

43

The Current C, T Transformation Rules of Quantum Field Theory Must be Redefined  

E-Print Network (OSTI)

In light of the transformation defined in the current quantum field theory, electromagnetic interaction is unchanged under time reversal. However, this kind of time reversal only lets in the Hamiltonian of the coordinate space, without considering that the creation and annihilation processes of particles should also be reversed when the concrete problems are calculated in momentum space. In fact, according to the current transformation of quantum field theory, creation operator of spinor particle is still creation operator and annihilation operator is also still annihilation operator. This result does not represent the real meaning of time reversal. In the interaction process, a particle's creation operator should become the annihilation operator and its annihilation operator should become the creation operator after time reversal. It is proved that when the reversion of creation and annihilation processes is considered in momentum space, under the condition of high energy, a great symmetry violation of time reversal would be caused in some low order processes of electromagnetic interaction just as the Compton scattering in which the propagation lines of fermions are contained. This result contradicts with the experiments of particle physics and is impossible. Meanwhile, it is proved that the normalization processes of the third order vertex angles of electromagnetic interaction also violate time reversal symmetry, no matter in the coordinate space or in the momentum space. But the symmetry violation is small with a magnitude order about 10(-5). The similar problems exist in the current C transformation of quantum field theory. The C transformation of creation and annihilation operator can not be consistent with the C transformation of spinor particle's wave functions in momentum space. We can obtain the correct C transformation of creation and annihilation operator, but can not obtain the correct C transformation of wave functions in momentum space. Therefore, the current rules of C,T transformations in quantum field theory has serious defect and should be redefined.

Mei Xiaochun

2010-03-13T23:59:59.000Z

44

Quantum fields as gravitational sources  

E-Print Network (OSTI)

The practice of setting quantum fields as sources for classical general relativity is examined. Several conceptual problems are identified which invalidate apparently innocuous equations. Alternative ways to links classical general relativity with quantum theory using Bohm's theory are proposed.

Mark J Hadley

2008-08-13T23:59:59.000Z

45

The structure of Green functions in quantum field theory with a general state  

E-Print Network (OSTI)

In quantum field theory, the Green function is usually calculated as the expectation value of the time-ordered product of fields over the vacuum. In some cases, especially in degenerate systems, expectation values over general states are required. The corresponding Green functions are essentially more complex than in the vacuum, because they cannot be written in terms of standard Feynman diagrams. Here, a method is proposed to determine the structure of these Green functions and to derive nonperturbative equations for them. The main idea is to transform the cumulants describing correlations into interaction terms.

Christian Brouder

2007-10-30T23:59:59.000Z

46

Renormalization of quantum field theory on curved space-times, a causal approach  

E-Print Network (OSTI)

The subject of the thesis is the construction of a perturbative quantum theory of interacting fields on a curved space-time, following a point of view pioneered by Stueckelberg and Bogoliubov and developed by Epstein-Glaser on the flat Minkowski space-time. In 2000, a breakthrough was done by Brunetti and Fredenhagen who were able to extend the Epstein-Glaser theory by exploiting the point of view developed by Radzikowski to define quantum states on a curved space-time in terms of wave-front sets. These results were further extended by Fredenhagen, Brunetti, Hollands, Wald, Rejzner, etc. to Yang-Mills fields and the gravitation. However, even for theories without gauge invariance, many mathematical details were left unexplored and unquestioned. Our task was precisely to derive fully rigorously this theory in the case there is no gauge invariance. We propose in our work a complete review of the result, solving numerous questions, adding many new results around this program and, eventually, giving more precise details on the counterterms and ambiguities in the renormalization process, and a deeper understanding of the geometry of the wave front set of the n-point functions.

Nguyen Viet Dang

2013-12-19T23:59:59.000Z

47

Gradient formula for the beta-function of 2d quantum field theory  

E-Print Network (OSTI)

We give a non-perturbative proof of a gradient formula for beta functions of two-dimensional quantum field theories. The gradient formula has the form \\partial_{i}c = - (g_{ij}+\\Delta g_{ij} +b_{ij})\\beta^{j} where \\beta^{j} are the beta functions, c and g_{ij} are the Zamolodchikov c-function and metric, b_{ij} is an antisymmetric tensor introduced by H. Osborn and \\Delta g_{ij} is a certain metric correction. The formula is derived under the assumption of stress-energy conservation and certain conditions on the infrared behaviour the most significant of which is the condition that the large distance limit of the field theory does not exhibit spontaneously broken global conformal symmetry. Being specialized to non-linear sigma models this formula implies a one-to-one correspondence between renormalization group fixed points and critical points of c.

Friedan, Daniel

2009-01-01T23:59:59.000Z

48

Quantum Physics Theory  

Science Conference Proceedings (OSTI)

Quantum Physics Theory. Summary: Theoretical work ... constant. The database is available at http://physics.nist.gov/hdel. Precise ...

2010-10-05T23:59:59.000Z

49

Physics as Quantum Information Processing: Quantum Fields as Quantum Automata 1  

E-Print Network (OSTI)

Physics as Quantum Information Processing: Quantum Fields as Quantum Automata 1 Giacomo Mauro D Nazionale di Fisica Nucleare, Gruppo IV, Sezione di Pavia Abstract. 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

D'Ariano, Giacomo Mauro

50

Quantum field theory in curved graphene spacetimes, Lobachevsky geometry, Weyl symmetry, Hawking effect, and all that  

E-Print Network (OSTI)

We extensively discuss the theoretical framework to make curved monolayer graphene a realization of quantum field theory in curved spacetime. We rely upon a model of the electron-phonon interaction that reproduces the standard semiclassical Dirac quantum field in a curved spacetime. This model holds for very long wavelengths of the graphene conductivity electrons involved. Provided the full description of the phonon-electron interaction is of a modified gravity-type, the core of the results presented here apply, with due changes, to that case too. Using local Weyl symmetry, we probe into the possibility to reproduce a Hawking effect. For the sake of making the test easier in a laboratory, the whole study is carried out for the case of purely spatial curvatures, and for conformally flat spacetimes. Since we show that for the sphere there is no intrinsic horizon, the focus is on the infinite different surfaces of constant negative Gaussian curvature. Even though, in those cases, deep reasons of Lobachevsky geometry seem to lead to unreachable event horizons, we show under which conditions the horizon is within reach. The Hawking effect, then, takes place on the Beltrami surface. We also explicitly study the spacetimes of the other two pseudospheres, and show their relation to de Sitter, and BTZ black-hole spacetimes. In the same limit that gives a reachable event horizon, these two cases, essentially, reduce to Beltrami. This, together with the fact that all the infinite surfaces in point are applicable to either one of the three pseudospheres, make us conjecture about the possibility for a Hawking effect for a generic surface of the family. The Hawking effect here manifests itself through a finite (Hawking) temperature electronic local density of states, that we exhibit.

Alfredo Iorio; Gaetano Lambiase

2013-08-01T23:59:59.000Z

51

Quantum Game Theory  

E-Print Network (OSTI)

Quantum game theory is the study of strategic behavior by agents with access to quantum technology. Broadly speaking, this technology can be employed in either of two ways: As part of a randomization device or as part of a communications protocol. We survey some of the main ideas from both branches of the subject.

Landsburg, Steven E

2011-01-01T23:59:59.000Z

52

Contribution from the interaction Hamiltonian to the expectation value of particle number with the non-equilibrium quantum field theory  

SciTech Connect

We develop the method analyzing particle number non-conserving phenomena with non-equilibrium quantum field-theory. In this study, we consider a CP violating model with interaction Hamiltonian that breaks particle number conservation. To derive the quantum Boltzmann equation for the particle number, we solve Schwinger-Dyson equation, which are obtained from two particle irreducible closed-time-path (2PI CTP) effective action. In this calculation, we show the contribution from interaction Hamiltonian to the time evolution of expectation value of particle number.

Hotta, Ryuuichi; Morozumi, Takuya; Takata, Hiroyuki [Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Tomsk state Pedagogical University Tomsk 634041 (Russian Federation)

2012-07-27T23:59:59.000Z

53

Beable-Guided Quantum Theories: Generalising Quantum Probability Laws  

E-Print Network (OSTI)

We introduce the idea of a {\\it beable-guided quantum theory}. Beable-guided quantum theories (BGQT) are generalisations of quantum theory, inspired by Bell's concept of beables. They modify the quantum probabilities for some specified set of fundamental events, histories, or other elements of quasiclassical reality by probability laws that depend on the realised configuration of beables. For example, they may define an additional probability weight factor for a beable configuration, independent of the quantum dynamics. BGQT can be fitted to observational data to provide foils against which to compare explanations based on standard quantum theory. For example, a BGQT could, in principle, characterise the effects attributed to dark energy or dark matter, or any other deviation from the predictions of standard quantum dynamics, without introducing extra fields or a cosmological constant. The complexity of the beable-guided theory would then parametrise how far we are from a standard quantum explanation. Less co...

Kent, Adrian

2013-01-01T23:59:59.000Z

54

A Proposed Alternative Low Energy Quantum Field Theory of Gravity Based on a Bose-Einstein Condensate Effect  

E-Print Network (OSTI)

An alternative quantum field theory for gravity is proposed for low energies based on an attractive effect between contaminants in a Bose-Einstein Condensate rather than on particle exchange. In the ``contaminant in condensate effect," contaminants cause a potential in an otherwise uniform condensate, forcing the condensate between two contaminants to a higher energy state. The energy of the system decreases as the contaminants come closer together, causing an attractive force between contaminants. It is proposed that mass-energy may have a similar effect on Einstein's space-time field, and gravity is quantized by the same method by which the contaminant in condensate effect is quantized. The resulting theory is finite and, if a physical condensate is assumed to underly the system, predictive. However, the proposed theory has several flaws at high energies and is thus limited to low energies. Falsifiable predictions are given for the case that the Higgs condensate is assumed to be the condensate underlying gravity.

Alexander Oshmyansky

2007-03-08T23:59:59.000Z

55

Quantum fields with topological defects  

E-Print Network (OSTI)

Domain walls, strings and monopoles are extended objects, or defects, of quantum origin with topologically non--trivial properties and macroscopic behavior. They are described in Quantum Field Theory in terms of inhomogeneous condensates. We review the related formalism in the framework of the spontaneous breakdown of symmetry.

M. Blasone; P. Jizba; G. Vitiello

2004-02-13T23:59:59.000Z

56

Quantum Structure of Field Theory and Standard Model Based on Infinity-free Loop Regularization/Renormalization  

E-Print Network (OSTI)

To understand better the quantum structure of field theory and standard model in particle physics, it is necessary to investigate carefully the divergence structure in quantum field theories (QFTs) and work out a consistent framework to avoid infinities. The divergence has got us into trouble since developing quantum electrodynamics in 1930s, its treatment via the renormalization scheme is satisfied not by all physicists, like Dirac and Feynman who have made serious criticisms. The renormalization group analysis reveals that QFTs can in general be defined fundamentally with the meaningful energy scale that has some physical significance, which motivates us to develop a new symmetry-preserving and infinity-free regularization scheme called loop regularization (LORE). A simple regularization prescription in LORE is realized based on a manifest postulation that a loop divergence with a power counting dimension larger than and equal to the space-time dimension must vanish. The LORE method is achieved without modifying original theory and leads the divergent Feynman loop integrals well-defined to maintain the divergence structure and meanwhile preserve basic symmetries of original theory. The crucial point in LORE is the presence of two intrinsic energy scales which play the roles of ultraviolet cut-off $M_c$ and infrared cut-off $\\mu_s$ to avoid infinities. The key concept in LORE is the introduction of irreducible loop integrals (ILIs) on which the regularization prescription acts, which leads to a set of gauge invariance consistency conditions between the regularized tensor-type and scalar-type ILIs. The evaluation of ILIs with ultraviolet-divergence-preserving (UVDP) parametrization naturally leads to Bjorken-Drell's analogy between Feynman diagrams and electric circuits. The LORE method has been shown to be applicable to both underlying and effective QFTs.

Yue-Liang Wu

2013-12-05T23:59:59.000Z

57

Warped Conformal Field Theory  

E-Print Network (OSTI)

We study field theories in two spacetime dimensions invariant under a chiral scaling symmetry that acts only on right-movers. The local symmetries include one copy of the Virasoro algebra and a U(1) current algebra. This differs from the 2d conformal group, but in some respects is equally powerful in constraining the theory. In particular, the symmetries on a torus lead to modular covariance of the partition function, which is used to derive a universal formula for the asymptotic density of states. For an application we turn to the holographic description of black holes in quantum gravity, motivated by the fact that the symmetries in the near horizon geometry of any extremal black hole are identical to those of a 2d field theory with chiral scaling. We consider two examples: black holes in warped AdS_3 in topologically massive gravity, and in string theory. In both cases, the density of states in the 2d field theory reproduces the Bekenstein-Hawking entropy of black holes in the gravity theory.

Detournay, Stephane; Hofman, Diego M

2012-01-01T23:59:59.000Z

58

Warped Conformal Field Theory  

E-Print Network (OSTI)

We study field theories in two spacetime dimensions invariant under a chiral scaling symmetry that acts only on right-movers. The local symmetries include one copy of the Virasoro algebra and a U(1) current algebra. This differs from the 2d conformal group, but in some respects is equally powerful in constraining the theory. In particular, the symmetries on a torus lead to modular covariance of the partition function, which is used to derive a universal formula for the asymptotic density of states. For an application we turn to the holographic description of black holes in quantum gravity, motivated by the fact that the symmetries in the near horizon geometry of any extremal black hole are identical to those of a 2d field theory with chiral scaling. We consider two examples: black holes in warped AdS_3 in topologically massive gravity, and in string theory. In both cases, the density of states in the 2d field theory reproduces the Bekenstein-Hawking entropy of black holes in the gravity theory.

Stephane Detournay; Thomas Hartman; Diego M. Hofman

2012-10-01T23:59:59.000Z

59

Quantum Dimensions and Quantum Galois Theory  

E-Print Network (OSTI)

The quantum dimensions of modules for vertex operator algebras are defined and their properties are discussed. The possible values of the quantum dimensions are obtained for rational vertex operator algebras. A criterion for simple currents of a rational vertex operator algebra is given. A full Galois theory for rational vertex operator algebras is established using the quantum dimensions.

Dong, Chongying; Xu, Feng

2012-01-01T23:59:59.000Z

60

The Thermal Aspects of Relativistic Quantum Field Theory as an Observational Window in a Deeper Layer of Quantum Space-Time or: Dirac's Revenge  

E-Print Network (OSTI)

In this paper we shall derive the thermal properties of the relativistic quantum vacuum from a more primordial underlying structure which shares some properties with the old Dirac-sea picture. We show in particular how the Tomita-KMS structure in RQFT is a consequence of the structure and dynamics of the underlying pattern of vacuum fluctuations. We explain the origin of the doubling phenomenon in thermofield theory and the duality symmetry between a local algebra of fields or observables and its commutant in RQFT and give an interpretation of the notion of thermal time.

Manfred Requardt

2013-09-05T23:59:59.000Z

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


61

The Anomalous Nambu-Goldstone Theorem in Relativistic/Nonrelativistic Quantum Field Theory  

E-Print Network (OSTI)

The anomalous Nambu-Goldstone (NG) theorem which is found as a violation of counting law of the number of NG bosons of the normal NG theorem in nonrelativistic and Lorentz-symmetry-violated relativistic theories is studied in detail, with emphasis on its mathematical aspect from Lie algebras, geometry to number theory. The basis of counting law of NG bosons in the anomalous NG theorem is examined by Lie algebras (local) and Lie groups (global). A quasi-Heisenberg algebra is found generically in various symmetry breaking schema of the anomalous NG theorem, and it indicates that it causes a violation/modification of the Heisenberg uncertainty relation in an NG sector which can be experimentally confirmed. The formalism of effective potential is presented for understanding the mechanism of anomalous NG theorem with the aid of our result of Lie algebras. After an investigation on a bosonic kaon condensation model with a finite chemical potential as an explicit Lorentz-symmetry-breaking parameter, a model Lagrangian approach on the anomalous NG theorem is given for our general discussion. Not only the condition of the counting law of true NG bosons, but also the mechanism to generate a mass of massive NG boson is also found by our examination on the kaon condensation model. Furthermore, the generation of a massive mode in the NG sector is understood by the quantum uncertainty relation of the Heisenberg algebra, obtained from a symmetry breaking of a Lie algebra, which realizes in the effective potential of the kaon condensation model. Hence the relation between a symmetry breaking scheme, a Heisenberg algebra, a mode-mode coupling, and the mechanism of mass generation in an NG sector is established. Finally, some relations between the Riemann hypothesis and the anomalous NG theorem are presented.

Tadafumi Ohsaku

2013-12-01T23:59:59.000Z

62

Quantum Mechanics and Representation Theory Columbia University  

E-Print Network (OSTI)

Quantum Mechanics and Representation Theory Peter Woit Columbia University Texas Tech, November 21 2013 Peter Woit (Columbia University) Quantum Mechanics and Representation Theory November 2013 1 / 30 #12;Does Anyone Understand Quantum Mechanics? "No One Understands Quantum Mechanics" "I think

Woit, Peter

63

Quantum proof systems and entanglement theory  

E-Print Network (OSTI)

Quantum complexity theory is important from the point of view of not only theory of computation but also quantum information theory. In particular, quantum multi-prover interactive proof systems are defined based on ...

Abolfathe Beikidezfuli, Salman

2009-01-01T23:59:59.000Z

64

Quantum field theory in the presence of a medium: Green's function expansions  

SciTech Connect

Starting from a Lagrangian and using functional-integration techniques, series expansions of Green's function of a real scalar field and electromagnetic field, in the presence of a medium, are obtained. The parameter of expansion in these series is the susceptibility function of the medium. Relativistic and nonrelativistic Langevin-type equations are derived. Series expansions for Lifshitz energy in finite temperature and for an arbitrary matter distribution are derived. Covariant formulations for both scalar and electromagnetic fields are introduced. Two illustrative examples are given.

Kheirandish, Fardin [Department of Physics, Islamic Azad University, Shahreza-Branch, Shahreza (Iran, Islamic Republic of); Salimi, Shahriar [Department of Physics, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

2011-12-15T23:59:59.000Z

65

Extended Grimus-Stockinger theorem and inverse square law violation in quantum field theory  

E-Print Network (OSTI)

We study higher-order corrections to the Grimus-Stockinger theorem dealing with the large-distance asymptotic behavior of the wave-packet modified neutrino propagator within the framework of field-theoretical description of the neutrino oscillation phenomenon. We discuss the possibility that these corrections are responsible for breakdown of the classical inverse-square law (ISL) at the macroscopic distances. In particular the ISL violation can be an explanation of the well-known reactor antineutrino anomaly.

Naumov, Vadim A

2013-01-01T23:59:59.000Z

66

Extended Grimus-Stockinger theorem and inverse square law violation in quantum field theory  

E-Print Network (OSTI)

We study higher-order corrections to the Grimus-Stockinger theorem dealing with the large-distance asymptotic behavior of the wave-packet modified neutrino propagator within the framework of field-theoretical description of the neutrino oscillation phenomenon. We discuss the possibility that these corrections are responsible for breakdown of the classical inverse-square law (ISL) at the macroscopic distances. In particular the ISL violation can be an explanation of the well-known reactor antineutrino anomaly.

Vadim A. Naumov; Dmitry S. Shkirmanov

2013-09-04T23:59:59.000Z

67

Quantum Dots: Theory  

SciTech Connect

This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.

Vukmirovic, Nenad; Wang, Lin-Wang

2009-11-10T23:59:59.000Z

68

Diffeomorphisms in group field theories  

SciTech Connect

We study the issue of diffeomorphism symmetry in group field theories (GFT), using the noncommutative metric representation introduced by A. Baratin and D. Oriti [Phys. Rev. Lett. 105, 221302 (2010).]. In the colored Boulatov model for 3d gravity, we identify a field (quantum) symmetry which ties together the vertex translation invariance of discrete gravity, the flatness constraint of canonical quantum gravity, and the topological (coarse-graining) identities for the 6j symbols. We also show how, for the GFT graphs dual to manifolds, the invariance of the Feynman amplitudes encodes the discrete residual action of diffeomorphisms in simplicial gravity path integrals. We extend the results to GFT models for higher-dimensional BF theories and discuss various insights that they provide on the GFT formalism itself.

Baratin, Aristide [Triangle de la Physique, CPHT Ecole Polytechnique, IPhT Saclay, LPT Orsay and Laboratoire de Physique Theorique, CNRS UMR 8627, Universite Paris XI, F-91405 Orsay Cedex (France); Girelli, Florian [School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia); Oriti, Daniele [Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Am Muehlenberg 1, 14467 Golm (Germany)

2011-05-15T23:59:59.000Z

69

Radiation reaction in nonrelativistic quantum theory. [Review  

SciTech Connect

Some recent work is reviewed on the quantum theory of radiation reaction. The starting point is the Heisenberg operator equation of motion for a nonrelativistic point electron coupled to the quantized electromagnetic field. It is shown that this equation, in contrast to its classical counterpart, leads to a finite value for the electrostatic self-energy of a point electron and, for values of the fine structure constant ..cap alpha.. approximately less than 1, admits neither runaway behavior nor noncausal motion. Furthermore, the correspondence limit of the solution to the quantum mechanical equation of motion agrees with that of the Lorentz--Dirac theory in the classical regime, but without the imposition of additional conditions and with no possibility of observable noncausality. Thus, a consistent picture of a classical point electron emerges in the correspondence limit of the quantum mechanical theory. 17 references.

Sharp, D.H.

1979-01-01T23:59:59.000Z

70

Prequantum Classical Statistical Field Theory: Fundamentals  

SciTech Connect

We present fundamentals of a prequantum model with hidden variables of the classical field type. In some sense this is the comeback of classical wave mechanics. Our approach also can be considered as incorporation of quantum mechanics into classical signal theory. All quantum averages (including correlations of entangled systems) can be represented as classical signal averages and correlations.

Khrennikov, Andrei [International Center for Mathematical Modelling in Physics and Cognitive Sciences, Linnaeus University, Vaexjoe, S-35195 (Sweden)

2011-03-28T23:59:59.000Z

71

Three approaches to classical thermal field theory  

SciTech Connect

Research Highlights: > Classical thermal field theory admits three equivalent path integral formulations. > Classical Feynman rules can be derived for all three formulations. > Quantum Feynman rules reduce to classical ones at high temperatures. > Classical Feynman rules become much simpler when superfields are introduced. - Abstract: In this paper we study three different functional approaches to classical thermal field theory, which turn out to be the classical counterparts of three well-known different formulations of quantum thermal field theory: the closed-time path (CTP) formalism, the thermofield dynamics (TFD) and the Matsubara approach.

Gozzi, E., E-mail: gozzi@ts.infn.it [Department of Physics, University of Trieste, Strada Costiera 11, Miramare - Grignano, 34151 Trieste (Italy); INFN, Sezione di Trieste (Italy); Penco, R., E-mail: rpenco@syr.edu [Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States)

2011-04-15T23:59:59.000Z

72

STATISTICAL MECHANICS AND FIELD THEORY  

E-Print Network (OSTI)

1. L. 1. Schiff, Quantum Mechanics, third edition (McGraw-two-dimensional quantum mechanics problem vith a potential,Theory Methods to Statistical Mechanics Chapter I The Use of

Samuel, S.A.

2010-01-01T23:59:59.000Z

73

Quantum Theory Event-Probability Interpretation  

Science Conference Proceedings (OSTI)

In this article the propagation of pointlike event probabilities in space is considered. New interpretation of Quantum Theory is formulated.

Quznetsov, Gunn [Chelyabinsk State University, Chelyabinsk, Ural (Russian Federation)

2011-03-28T23:59:59.000Z

74

Foundations of quantum theory and thermodynamics  

Science Conference Proceedings (OSTI)

Physical reasons to support the statement that Quantum theory (Quantum Gravity in particular as well as Classical Gravity) loose applicability due to Thermodynamical effects are presented. The statement is based on several points: 1. N.Bohr requirement that measuring units must have macro size is one of common fundamentals of Quantum theory. 2. The Reference Systemthe base notion of Classical and Quantum theory and of any observation process as well

Victor Olkhov

1998-01-01T23:59:59.000Z

75

Quantum optical experiments and fundamentals of quantum theory  

E-Print Network (OSTI)

Quantum optical experiments and fundamentals of quantum theory Miloslav Dusek Department of Optics, Palacky University 17. listopadu 50, 772 00 Olomouc, Czech Republic ABSTRACT Quantum optics has o ered new possibilities for experimental tests of basic principles of quantum mechanics. It enables us to experimentally

Dusek, Miloslav

76

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

From Quantum Mechanics to String Theory Relativity (why it makes sense) Quantum mechanics, 2009 #12;Quantum Mechanics: Measurement and Uncertainty Thursday, May 7, 2009 #12;Puzzle: The Stern it. Quantum mechanics understanding: the particle exists in a state without definite position

77

Directional Entanglement of Quantum Fields with Quantum Geometry  

E-Print Network (OSTI)

A modification of quantum field theory on large scales is conjectured to result from effects of Planck scale limits on directional information. Transversely localized solutions of the relativistic wave equation are used to show that the path of a massless particle with wavelength $\\lambda$ that travels a distance $z$ has a wave function with indeterminacy in direction given by the diffraction scale, $\\langle \\Delta \\theta^2\\rangle > \\sqrt{2}\\lambda /\\pi z$. It is conjectured that the spatial structure of all quantum field states is influenced by a new kind of directional indeterminacy of quantum geometry set by the Planck length, $l_P$, that does not occur in the usual classical background geometry. Entanglement of field and geometry states is described in the small angle approximation. It is shown to have almost no effect on local measurements, microscopic particle interactions, or measurements of propagating states that depend only on longitudinal coordinates, but to significantly alter field states in systems larger than $\\approx \\lambda^2/l_P $ that depend on transverse coordinates or direction. It reduces the information content of fields in large systems, consistent with holographic bounds from gravitation theory, and may lead to quantum-geometrical directional fluctuations of massive bodies detectable with interferometers. Possible connections are discussed with field vacuum energy, black hole information, and inflationary fluctuations.

Craig J. Hogan

2013-12-30T23:59:59.000Z

78

Shape Dynamics and Effective Field Theory  

E-Print Network (OSTI)

Shape Dynamics is a gauge theory based on spatial diffeomorphism- and Weyl-invariance which is locally indistinguishable form classical General Relativity. If taken seriously, it suggests that the spacetime--geometry picture that underlies General Relativity can be replaced by a picture based on spatial conformal geometry. This classically well understood trading of gauge symmetries opens new conceptual avenues in many approaches to quantum gravity. I focus on the general implications for quantum gravity and effective field theory and consider the application of the Shape Dynamics picture in the exact renormalization group approaches to gravity, loop- and polymer- quantization approaches to gravity and low energy effective field theories. I also discuss the interpretation of known results through in the Shape Dynamics picture, in particular holographic renormalization and the problem of time in canonical quantum gravity.

Tim Koslowski

2013-05-07T23:59:59.000Z

79

Quantum theory and gravity from a space-time wave  

E-Print Network (OSTI)

The quantum properties and gravitational field of a particle system are derived from a quantum theory of space-time. A field with quantized space-time vibrations has the same properties and equations for a particle field in quantum theory. The statistical nature of quantum mechanics can be explained by assuming the amplitudes of space-time waves serve as additional variables of the theory. The difficulty of associating a physical meaning with the quantum wave due to the unobservable overall phase is resolved. Instead of attempting to derive the properties of space-time from a quantum theory, as is usually the case, the quantum properties of matter can be derived from a theory of space-time. The energy of a space-time wave must correspond to the rest mass of a real particle; the vibrations are thus quantized. It is also demonstrated that the geometrical structure derived from a quantized space-time vibration is equivalent to the gravitational field of a point mass in general relativity. The fundamental questions of why and how a point mass gives rise to its gravitational singularity and curved space-time geometry can thereby be explained.

Hou Yau

2007-06-01T23:59:59.000Z

80

Quantum control theory and applications: A survey  

E-Print Network (OSTI)

This paper presents a survey on quantum control theory and applications from a control systems perspective. Some of the basic concepts and main developments (including open-loop control and closed-loop control) in quantum control theory are reviewed. In the area of open-loop quantum control, the paper surveys the notion of controllability for quantum systems and presents several control design strategies including optimal control, Lyapunov-based methodologies, variable structure control and quantum incoherent control. In the area of closed-loop quantum control, the paper reviews closed-loop learning control and several important issues related to quantum feedback control including quantum filtering, feedback stabilization, LQG control and robust quantum control.

Daoyi Dong; Ian R Petersen

2009-10-13T23:59:59.000Z

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


81

Quantum control theory and applications: A survey  

E-Print Network (OSTI)

This paper presents a survey on quantum control theory and applications from a control systems perspective. Some of the basic concepts and main developments (including open-loop control and closed-loop control) in quantum control theory are reviewed. In the area of open-loop quantum control, the paper surveys the notion of controllability for quantum systems and presents several control design strategies including optimal control, Lyapunov-based methodologies, variable structure control and quantum incoherent control. In the area of closed-loop quantum control, the paper reviews closed-loop learning control and several important issues related to quantum feedback control including quantum filtering, feedback stabilization, LQG control and robust quantum control.

Dong, Daoyi

2009-01-01T23:59:59.000Z

82

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

From Quantum Mechanics to String Theory Relativity (why it makes sense) Quantum mechanics) New Particles anti-particles (combining special relativity and quantum mechanics pions (mediator mechanics, implies an infinite tower of negative energy states, rather than a ground state suppose

83

From Quantum Mechanics to String Theory  

E-Print Network (OSTI)

From Quantum Mechanics to String Theory Relativity (why it makes sense) Quantum mechanics Extra Dimensions Strings and the Strong Force Thursday, June 4, 2009 #12;The Higgs Mechanism Summary Mechanical Particle Physics General Relativistic Quantum Gravity increasing speed decreasing size increasing

84

Quantum bouncer: theory and experiment  

E-Print Network (OSTI)

The quantum bouncer (QB) concept is a known QM textbook example of confined particle, namely, a solution to the 1D Schroedinger equation for a linear potential (the so-called Airy equation). It would be a great methodological challenge to create such a QM object in laboratory. An attempt of observation of the QB ``running'' in the horizontal direction was recently made by the international team at the Laue-Langevin Institute, Grenoble. The experiment was performed with ultra-cold neutrons. In this paper, the experiment is analyzed in view of the authors' claim that ``neutron quantum states in Earth gravitational field'' are observed. The experimental apparatus is designed for measurements of horizontal flux of neutrons passing through an absorbing wave guide with a variable height of absorber. From our analysis, it follows, however, that in such a layout measured data are not sensitive to quantum probability density in the vertical direction. The overall conclusion is made that the experimental data do not contain sufficient information to justify the claim.

Anatoli Andrei Vankov

2009-06-28T23:59:59.000Z

85

Diagrammar in classical scalar field theory  

SciTech Connect

In this paper we analyze perturbatively a g{phi}{sup 4}classical field theory with and without temperature. In order to do that, we make use of a path-integral approach developed some time ago for classical theories. It turns out that the diagrams appearing at the classical level are many more than at the quantum level due to the presence of extra auxiliary fields in the classical formalism. We shall show that a universal supersymmetry present in the classical path-integral mentioned above is responsible for the cancelation of various diagrams. The same supersymmetry allows the introduction of super-fields and super-diagrams which considerably simplify the calculations and make the classical perturbative calculations almost 'identical' formally to the quantum ones. Using the super-diagrams technique, we develop the classical perturbation theory up to third order. We conclude the paper with a perturbative check of the fluctuation-dissipation theorem. - Highlights: > We provide the Feynman diagrams of perturbation theory for a classical field theory. > We give a super-formalism which links the quantum diagrams to the classical ones. > We check perturbatively the fluctuation-dissipation theorem.

Cattaruzza, E., E-mail: Enrico.Cattaruzza@gmail.com [Department of Physics (Miramare Campus), University of Trieste, Strada Costiera 11, Miramare-Grignano 34014, Trieste (Italy); Gozzi, E., E-mail: gozzi@ts.infn.it [Department of Physics (Miramare Campus), University of Trieste, Strada Costiera 11, Miramare-Grignano 34014, Trieste (Italy); INFN, Sezione di Trieste (Italy); Francisco Neto, A., E-mail: antfrannet@gmail.com [Departamento de Engenharia de Producao, Administracao e Economia, Escola de Minas, Campus Morro do Cruzeiro, UFOP, 35400-000 Ouro Preto MG (Brazil)

2011-09-15T23:59:59.000Z

86

The Localized Quantum Vacuum Field  

E-Print Network (OSTI)

A model for the localized quantum vacuum is proposed in which the zero-point energy of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated to the zero-point energy of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift; it also offers a new insight into the Zitterbewegung of material particles.

Daniela Dragoman

2006-03-01T23:59:59.000Z

87

Free Field Theory as a String Theory?  

E-Print Network (OSTI)

An approach to systematically implement open-closed string duality for free large $N$ gauge theories is summarised. We show how the relevant closed string moduli space emerges from a reorganisation of the Feynman diagrams contributing to free field correlators. We also indicate why the resulting integrand on moduli space has the right features to be that of a string theory on $AdS$.

Rajesh Gopakumar

2004-09-23T23:59:59.000Z

88

Invariants from classical field theory  

Science Conference Proceedings (OSTI)

We introduce a method that generates invariant functions from perturbative classical field theories depending on external parameters. By applying our methods to several field theories such as Abelian BF, Chern-Simons, and two-dimensional Yang-Mills theory, we obtain, respectively, the linking number for embedded submanifolds in compact varieties, the Gauss' and the second Milnor's invariant for links in S{sup 3}, and invariants under area-preserving diffeomorphisms for configurations of immersed planar curves.

Diaz, Rafael [Grupo de Fisica-Matematica, Universidad Experimental Politecnica de las Fuerzas Armadas, Caracas 1010 (Venezuela); Leal, Lorenzo [Centro de Fisica Teorica y Computacional, Universidad Central de Venezuela, Caracas 1041-A (Venezuela)

2008-06-15T23:59:59.000Z

89

On Information Theory, Spectral Geometry and Quantum Gravity  

E-Print Network (OSTI)

We show that there exists a deep link between the two disciplines of information theory and spectral geometry. This allows us to obtain new results on a well known quantum gravity motivated natural ultraviolet cutoff which describes an upper bound on the spatial density of information. Concretely, we show that, together with an infrared cutoff, this natural ultraviolet cutoff beautifully reduces the path integral of quantum field theory on curved space to a finite number of ordinary integrations. We then show, in particular, that the subsequent removal of the infrared cutoff is safe.

Achim Kempf; Robert Martin

2007-08-01T23:59:59.000Z

90

Parabolic Whittaker Functions and Topological Field Theories I  

E-Print Network (OSTI)

First, we define a generalization of the standard quantum Toda chain inspired by a construction of quantum cohomology of partial flags spaces GL(\\ell+1)/P, P a parabolic subgroup. Common eigenfunctions of the parabolic quantum Toda chains are generalized Whittaker functions given by matrix elements of infinite-dimensional representations of gl(\\ell+1). For maximal parabolic subgroups (i.e. for P such that GL(\\ell+1)/P=\\mathbb{P}^{\\ell}) we construct two different representations of the corresponding parabolic Whittaker functions as correlation functions in topological quantum field theories on a two-dimensional disk. In one case the parabolic Whittaker function is given by a correlation function in a type A equivariant topological sigma model with the target space \\mathbb{P}^{\\ell}. In the other case the same Whittaker function appears as a correlation function in a type B equivariant topological Landau-Ginzburg model related with the type A model by mirror symmetry. This note is a continuation of our project of establishing a relation between two-dimensional topological field theories (and more generally topological string theories) and Archimedean (\\infty-adic) geometry. From this perspective the existence of two, mirror dual, topological field theory representations of the parabolic Whittaker functions provide a quantum field theory realization of the local Archimedean Langlands duality for Whittaker functions. The established relation between the Archimedean Langlands duality and mirror symmetry in two-dimensional topological quantum field theories should be considered as a main result of this note.

Anton Gerasimov; Dimitri Lebedev; Sergey Oblezin

2010-02-12T23:59:59.000Z

91

Entanglement Entropy in Scalar Field Theory  

E-Print Network (OSTI)

Understanding the dependence of entanglement entropy on the renormalized mass in quantum field theories can provide insight into phenomena such as quantum phase transitions, since the mass varies in a singular way near the transition. Here we perturbatively calculate the entanglement entropy in interacting scalar field theory, focussing on the dependence on the field's mass. We study lambda phi^4 and g phi^3 theories in their ground state. By tracing over a half space, using the replica trick and position space Green's functions on the cone, we show that space-time volume divergences cancel and renormalization can be consistently performed in this conical geometry. We establish finite contributions to the entanglement entropy up to two-loop order, involving a finite area law. The resulting entropy is simple and intuitive: the free theory result in d=3 (that we included in an earlier publication) Delta S ~ A m^2 ln(m^2) is altered, to leading order, by replacing the bare mass m by the renormalized mass m_r eva...

Hertzberg, Mark P

2012-01-01T23:59:59.000Z

92

A symmetrical theory of nonrelativistic quantum mechanics  

E-Print Network (OSTI)

This paper presents a new Symmetrical Theory (ST) of nonrelativistic quantum mechanics which postulates: quantum mechanics is a theory about complete experiments, not particles; a complete experiment is maximally described by a complex transition amplitude density; and this transition amplitude density never collapses. This new ST is compared to the Conventional Theory (CT) of nonrelativistic quantum mechanics for the analysis of a beam-splitter experiment. The ST makes several experimentally testable predictions that differ from the CT, which can be checked using existing technology. The ST also solves one part of the CT measurement problem, and resolves some of the paradoxes of the CT. This nonrelativistic ST is the low energy limit of a relativistic ST presented in an earlier paper \\cite{Heaney1}.

Michael B. Heaney

2013-10-20T23:59:59.000Z

93

Complementarity and Entanglement in Quantum Information Theory  

E-Print Network (OSTI)

The restrictions that nature places on the distribution of correlations in a multipartite quantum system play fundamental roles in the evolution of such systems, and yield vital insights into the design of protocols for the quantum control of ensembles with potential applications in the field of quantum computing. We show how this entanglement sharing behavior may be studied in increasingly complex systems of both theoretical and experimental significance and demonstrate that entanglement sharing, as well as other unique features of entanglement, e.g. the fact that maximal information about a multipartite quantum system does not necessarily entail maximal information about its component subsystems, may be understood as specific consequences of the phenomenon of complementarity extended to composite quantum systems. We also present a local hidden-variable model supplemented by an efficient amount of classical communication that reproduces the quantum-mechanical predictions for the entire class of Gottesman-Kni...

Tessier, T E

2004-01-01T23:59:59.000Z

94

$N=2$ Supersymmetric Integrable Models and Topological Field Theories  

E-Print Network (OSTI)

These lectures review some of the basic properties of $N=2$ superconformal field theories and the corresponding topological field theories. One of my basic aims is to show how the techniques of topological field theory can be used to compute effective \\LG potentials for perturbed $N=2$ superconformal field theories. In particular, I will briefly discuss the application of these ideas to $N=2$ supersymmetric quantum integrable models. (Lectures given at the Summer School on High Energy Physics and Cosmology, Trieste, Italy, June 15th -- July 3rd, 1992. To appear in the proceedings.)

Warner, Nicholas P

1993-01-01T23:59:59.000Z

95

String field theory and tachyon condensation  

E-Print Network (OSTI)

In this thesis I discuss various aspects of Witten's cubic string field theory. After a brief review of the basics of string field theory we begin by showing how string field theory can be used to check certain conjectures ...

Ellwood, Ian Thomas, 1977-

2004-01-01T23:59:59.000Z

96

Analytic progress in open string field theory  

E-Print Network (OSTI)

Open string field theory provides an action functional for open string fields, and it is thus a manifestly off-shell formulation of open string theory. The solutions to the equation of motion of open string field theory ...

Kiermaier, Michael Stefan

2009-01-01T23:59:59.000Z

97

Quantum theory of photonic crystal polaritons  

E-Print Network (OSTI)

We formulate a full quantum mechanical theory of the interaction between electromagnetic modes in photonic crystal slabs and quantum well excitons embedded in the photonic structure. We apply the formalism to a high index dielectric layer with a periodic patterning suspended in air. The strong coupling between electromagnetic modes lying above the cladding light line and exciton center of mass eigenfunctions manifests itself with the typical anticrossing behavior. The resulting band dispersion corresponds to the quasi-particles coming from the mixing of electromagnetic and material excitations, which we call photonic crystal polaritons. We compare the results obtained by using the quantum theory to variable angle reflectance spectra coming from a scattering matrix approach, and we find very good quantitative agreement.

D. Gerace; M. Agio; L. C. Andreani

2004-02-09T23:59:59.000Z

98

Causal signal transmission by quantum fields. II. Quantum-statistical response of interacting bosons  

E-Print Network (OSTI)

We analyse nonperturbatively signal transmission patterns in Green's functions of interacting quantum fields. Quantum field theory is re-formulated in terms of the nonlinear quantum-statistical response of the field. This formulation applies equally to interacting relativistic fields and nonrelativistic models. Of crucial importance is that all causality properties to be expected of a response formulation indeed hold. Being by construction equivalent to Schwinger's closed-time-loop formalism, this formulation is also shown to be related naturally to both Kubo's linear response and Glauber's macroscopic photodetection theories, being a unification of the two with generalisation to the nonlinear quantum-statistical response problem. In this paper we introduce response formulation of bosons; response reformulation of fermions will be subject of a separate paper.

L. I. Plimak; S. Stenholm

2008-04-25T23:59:59.000Z

99

Introduction to string theory and conformal field theory  

Science Conference Proceedings (OSTI)

A concise survey of noncritical string theory and two-dimensional conformal field theory is presented. A detailed derivation of a conformal anomaly and the definition and general properties of conformal field theory are given. Minimal string theory, which is a special version of the theory, is considered. Expressions for the string susceptibility and gravitational dimensions are derived.

Belavin, A. A., E-mail: belavin@itp.ac.ru; Tarnopolsky, G. M., E-mail: Hetzif@yandex.r [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation)

2010-05-15T23:59:59.000Z

100

Quantum cryptography: theory and practice  

E-Print Network (OSTI)

A highly attenuated laser pulse which gives a weak coherent state is widely used in quantum key distribution (QKD) experiments. A weak coherent state has multi-photon components, which opens up a security loophole to the sophisticated eavesdropper. With a small adjustment of the hardware, we prove that the decoy state method can close this loophole and substantially improve the QKD performance. We also propose a few practical decoy state protocols, study statistical fluctuations and perform experimental demonstrations. Moreover, we apply the methods from entanglement distillation protocols based on two-way classical communication to improve the decoy state QKD performance. Furthermore, we study the decoy state methods for other single photon sources, such as triggering parametric down-conversion (PDC) source. We propose a model and post-processing scheme for the entanglement-based QKD with a PDC source. Although the model is proposed to study the entanglement-based QKD, we emphasize that our generic model may also be useful for other non-QKD experiments involving a PDC source. By simulating a real PDC experiment, we show that the entanglement-based QKD can achieve longer maximal secure distance than the single-photon-based QKD schemes. We present a time-shift attack that exploits the efficiency mismatch of two single photon detectors in a QKD system. This eavesdropping strategy can be realized by current technology. We also discuss counter measures against the attack and study the security of a QKD system with efficiency mismatch detectors.

Xiongfeng Ma

2008-08-10T23:59:59.000Z

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101

THE OBJECTIVE INDEFINITENESS INTERPRETATION OF QUANTUM MECHANICS: Partition logic, logical information theory, and quantum mechanics  

E-Print Network (OSTI)

THE OBJECTIVE INDEFINITENESS INTERPRETATION OF QUANTUM MECHANICS: Partition logic, logical information theory, and quantum mechanics David Ellerman University of California at Riverside www ago that quantum mechanics was not compatible with Boolean logic, then the natural thing to do would

Wüthrich, Christian

102

Computers for Lattice Field Theories  

E-Print Network (OSTI)

Parallel computers dedicated to lattice field theories are reviewed with emphasis on the three recent projects, the Teraflops project in the US, the CP-PACS project in Japan and the 0.5-Teraflops project in the US. Some new commercial parallel computers are also discussed. Recent development of semiconductor technologies is briefly surveyed in relation to possible approaches toward Teraflops computers.

Y. Iwasaki

1994-01-26T23:59:59.000Z

103

From Entropic Dynamics to Quantum Theory  

SciTech Connect

Non-relativistic quantum theory is derived from information codified into an appropriate statistical model. The basic assumption is that there is an irreducible uncertainty in the location of particles so that the configuration space is a statistical manifold. The dynamics then follows from a principle of inference, the method of Maximum Entropy. The concept of time is introduced as a convenient way to keep track of change. The resulting theory resembles both Nelson's stochastic mechanics and general relativity. The statistical manifold is a dynamical entity: its geometry determines the evolution of the probability distribution which, in its turn, reacts back and determines the evolution of the geometry. There is a new quantum version of the equivalence principle: 'osmotic' mass equals inertial mass. Mass and the phase of the wave function are explained as features of purely statistical origin.

Caticha, Ariel [Department of Physics, University at Albany-SUNY, Albany, NY 12222 (United States)

2009-12-08T23:59:59.000Z

104

Parity violating quantum kinetic theory in (2+1)-dimensions  

E-Print Network (OSTI)

We study the kinetic theory for a (2+1)-dimensional fermionic system with special emphasis on the parity violating properties associated with the fermion mass. The Wigner function approach is used to derive hydrodynamical transport coefficients to the first spatial derivative order. As a first attempt, the collisions between fermions are neglected. The resulting system is dissipationless. The parity violating Hall electric conductivity has the same temperature and chemical potential dependence as the quantum field theory result at one-loop. Vorticity dependent transport properties, which were not considered before, also emerge naturally in this approach.

Jiunn-Wei Chen; Jian-Hua Gao; Juan Liu; Shi Pu; Qun Wang

2013-05-08T23:59:59.000Z

105

Experimental test of the "special state" theory of quantum measurement  

E-Print Network (OSTI)

An experimental test of the "special state" theory of quantum measurement is proposed. It should be feasible with present-day laboratory equipment and involves a slightly elaborated Stern-Gerlach setup. The "special state" theory is conservative with respect to quantum mechanics, but radical with respect to statistical mechanics, in particular regarding the arrow of time. In this article background material is given on both quantum measurement and statistical mechanics aspects. For example, it is shown that future boundary conditions would not contradict experience, indicating that the fundamental equal-a-priori-probability assumption at the foundations of statistical mechanics is far too strong (since future conditioning reduces the class of allowed states). The test is based on a feature of this theory that was found necessary in order to recover standard (Born) probabilities in quantum measurements. Specifically, certain systems should have "noise" whose amplitude follows the long-tailed Cauchy distribution. This distribution is marked by the occasional occurrence of extremely large signals as well as a non-self-averaging property. The proposed test is a variant of the Stern-Gerlach experiment in which protocols are devised, some of which will require the presence of this noise, some of which will not. The likely observational schemes would involve the distinction between detection and non-detection of that "noise". The signal to be detected (or not) would be either single photons in the visible and UV range or electric fields (and related excitations) in the neighborhood of the ends of the magnets.

L. S. Schulman

2013-10-09T23:59:59.000Z

106

Principles of Arrangement Field Theory  

E-Print Network (OSTI)

In this paper I attempt to summarize the fundamental principles which underlie to Arrangement Field Theory. In my intention the exposition would be the most possible intelligible and self-contained. However the exposed concepts are revisited in the light of the new researches, so that they could appear slightly different than in the previous works. Much emphasis is posed here to the power of theory to predict the number of fermionic families (flavours) and space-time dimensions. I also give a quick glance to the entanglement phenomenon and its interpretation as microscopic wormhole.

Diego Marin

2012-07-07T23:59:59.000Z

107

Quantum Computing and Lie Theory Feynman's suggestion that the only effective way to model quantum phe-  

E-Print Network (OSTI)

Quantum Computing and Lie Theory Feynman's suggestion that the only effective way to model quantum phe- nomena on a computer would be to build a computer that made use of quantum mechanics was one of the cornerstones of the birth of quantum com- puting. In his later years he studied both classical and quantum

D'Agnolo, Andrea

108

The Quantum Spin Hall Effect: Theory and Experiment  

SciTech Connect

The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Recently, a new class of topological insulators has been proposed. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. In two dimensions the helical edge states give rise to the quantum spin Hall (QSH) effect, in the absence of any external magnetic field. Here we review a recent theory which predicts that the QSH state can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the band structure changes from a normal to an 'inverted' type at a critical thickness d{sub c}. We present an analytical solution of the helical edge states and explicitly demonstrate their topological stability. We also review the recent experimental observation of the QSH state in HgTe/(Hg,Cd)Te quantum wells. We review both the fabrication of the sample and the experimental setup. For thin quantum wells with well width d{sub QW} < 6.3 nm, the insulating regime shows the conventional behavior of vanishingly small conductance at low temperature. However, for thicker quantum wells (d{sub QW} > 6.3 nm), the nominally insulating regime shows a plateau of residual conductance close to 2e{sup 2}/h. The residual conductance is independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance is destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, d{sub c} = 6.3 nm, is also independently determined from the occurrence of a magnetic field induced insulator to metal transition.

Konig, Markus; Buhmann, Hartmut; Molenkamp, Laurens W.; /Wurzburg U.; Hughes, Taylor L.; /Stanford U., Phys. Dept.; Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-03-19T23:59:59.000Z

109

General quantum modeling of combining concepts: A quantum field model in Fock space  

E-Print Network (OSTI)

We extend a quantum model in Hilbert space developed in Aerts (2007a) into a quantum field theoric model in Fock space for the modeling of the combination of concepts. Items and concepts are represented by vectors in Fock space and membership weights of items are modeled by quantum probabilities. We apply this theory to model the disjunction of concepts and show that the predictions of our theory for the membership weights of items regarding the disjunction of concepts match with great accuracy the complete set of results of an experiment conducted by Hampton (1988b). It are the quantum effects of interference and superposition of that are at the origin of the effects of overextension and underextension observed by Hampton as deviations from a classical use of the disjunction. It is essential for the perfect matches we obtain between the predictions of the quantum field model and Hamptons experimental data that items can be in superpositions of different numbers states which proves that the genuine structure of quantum field theory is needed to match predictions with experimental data.

Diederik Aerts

2007-01-01T23:59:59.000Z

110

Quantum Tetrahedra  

E-Print Network (OSTI)

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

Mauro Carfora; Annalisa Marzuoli; Mario Rasetti

2010-01-25T23:59:59.000Z

111

The Quantum Spin Hall Effect: Theory and Experiment  

Science Conference Proceedings (OSTI)

The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Recently, a new class of topological insulators has been proposed. These topological insulators have an insulating gap in the bulk, but have topologically protected edge states due to the time reversal symmetry. In two dimensions the helical edge states give rise to the quantum spin Hall (QSH) effect, in the absence of any external magnetic field. Here we review a recent theory which predicts that the QSH state can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the band structure changes from a normal to an 'inverted' type at a critical thickness d{sub c}. We present an analytical solution of the helical edge states and explicitly demonstrate their topological stability. We also review the recent experimental observation of the QSH state in HgTe/(Hg,Cd)Te quantum wells. We review both the fabrication of the sample and the experimental setup. For thin quantum wells with well width d{sub QW} 6.3 nm), the nominally insulating regime shows a plateau of residual conductance close to 2e{sup 2}/h. The residual conductance is independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance is destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, d{sub c} = 6.3 nm, is also independently determined from the occurrence of a magnetic field induced insulator to metal transition.

Konig, Markus; Buhmann, Hartmut; Molenkamp, Laurens W.; /Wurzburg U.; Hughes, Taylor L.; /Stanford U., Phys. Dept.; Liu, Chao-Xing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-03-19T23:59:59.000Z

112

Quantum mechanics as quantum information (and only a little more), Quantum Theory: Reconsideration of Foundations  

E-Print Network (OSTI)

In this paper, I try once again to cause some good-natured trouble. The issue remains, when will we ever stop burdening the taxpayer with conferences devoted to the quantum foundations? The suspicion is expressed that no end will be in sight until a means is found to reduce quantum theory to two or three statements of crisp physical (rather than abstract, axiomatic) significance. In this regard, no tool appears better calibrated for a direct assault than quantum information theory. Far from a strained application of the latest fad to a time-honored problem, this method holds promise precisely because a large partbut not allof the structure of quantum theory has always concerned information. It is just that the physics community needs reminding. This paper, though takingquant-ph/0106166 as its core, corrects one mistake and offers several observations beyond the previous version. In particular, I identify one element of quantum mechanics that I would not label a subjective term in the theoryit is the integer parameter D traditionally ascribed to a quantum system via its Hilbert-space dimension. 1

Christopher A. Fuchs

2002-01-01T23:59:59.000Z

113

Quantum Gauged Neural Network: U(1) Gauge Theory  

E-Print Network (OSTI)

A quantum model of neural network is introduced and its phase structure is examined. The model is an extension of the classical Z(2) gauged neural network of learning and recalling to a quantum model by replacing the Z(2) variables, $S_i = \\pm1$ of neurons and $J_{ij} =\\pm1$ of synaptic connections, to the U(1) phase variables, $S_i = \\exp(i\\phi_i)$ and $J_{ij} = \\exp(i\\theta_{ij}) $. These U(1) variables describe the phase parts of the wave functions (local order parameters) of neurons and synaptic connections. The model takes the form similar to the U(1) Higgs lattice gauge theory, the continuum limit of which is the well known Ginzburg-Landau theory of superconductivity. Its current may describe the flow of electric voltage along axons and chemical materials transfered via synaptic connections. The phase structure of the model at finite temperatures is examined by the mean-field theory, and Coulomb, Higgs and confinement phases are obtained. By comparing with the result of the Z(2) model, the quantum effects is shown to weaken the ability of learning and recalling.

Yukari Fujita; Tetsuo Matsui

2002-06-30T23:59:59.000Z

114

Formulating Quantum Theory as a Causally Neutral Theory of Bayesian Inference  

E-Print Network (OSTI)

Quantum theory can be viewed as a generalization of classical probability theory, but the analogy as it has been developed so far is not complete. Classical probability theory is independent of causal structure, whereas the conventional quantum formalism requires causal structure to be fixed in advance. In this paper, we develop the formalism of quantum conditional states, which unifies the description of experiments involving two systems at a single time with the description of those involving a single system at two times. The analogies between quantum theory and classical probability theory are expressed succinctly within the formalism and it unifies the mathematical description of distinct concepts, such as ensemble preparation procedures, measurements, and quantum dynamics. We introduce a quantum generalization of Bayes' theorem and the associated notion of Bayesian conditioning. Conditioning a quantum state on a classical variable is the correct rule for updating quantum states in light of classical data...

Leifer, M S

2011-01-01T23:59:59.000Z

115

Understanding High-Temperature Superconductors with Quantum Cluster Theories  

SciTech Connect

Quantum cluster theories are a set of approaches for the theory of correlated and disordered lattice systems, which treat correlations within the cluster explicitly, and correlations at longer length scales either perturbatively or within a mean-field approximation. These methods become exact when the cluster size diverges, and most recover the corresponding (dynamical) mean-field approximation when the cluster size becomes one. Here we will review systematic dynamical cluster simulations of the two-dimensional Hubbard model, that display phenomena remarkably similar to those found in the cuprates, including antiferromagnetism, superconductivity and pseudogap behavior. We will then discuss results for the structure of the pairing mechanism in this model, obtained from a combination of dynamical cluster results and diagrammatic techniques.

Maier, Thomas A [ORNL; Jarrell, Mark [University of Cincinnati; Scalapino, Douglas [University of California, Santa Barbara

2007-01-01T23:59:59.000Z

116

Aging Logarithmic Galilean Field Theories  

E-Print Network (OSTI)

We analytically compute correlation and response functions of scalar operators for the systems with Galilean and corresponding aging symmetries for general spatial dimensions $d$ and dynamical exponent $z$, along with their logarithmic and logarithmic squared extensions, using the gauge/gravity duality. These non-conformal extensions of the aging geometry are marked by two dimensionful parameters, eigenvalue $\\mathcal M$ of an internal coordinate and aging parameter $\\alpha$. We further perform systematic investigations on two-time response functions for general $d$ and $z$, and identify the growth exponent as a function of the scaling dimensions $\\Delta$ of the dual field theory operators and aging parameter $\\alpha$ in our theory. The initial growth exponent is only controlled by $\\Delta$, while its late time behavior by $\\alpha$ as well as $\\Delta$. These behaviors are separated by a time scale order of the waiting time. We attempt to make contact our results with some field theoretical growth models, such as Kim-Kosterlitz model at higher number of spatial dimensions $d$.

Seungjoon Hyun; Jaehoon Jeong; Bom Soo Kim

2013-03-29T23:59:59.000Z

117

Non-commutative Field Theory, Translational Invariant Products and Ultraviolet/Infrared Mixing  

E-Print Network (OSTI)

We review the Moyal and Wick-Voros products, and more in general the translation invariant non-commutative products, and apply them to classical and quantum field theory. We investigate phi^4 field theories calculating their Green's functions up to one-loop for the two- and four-point cases. We also review the connections of these theories with Drinfeld twists.

Galluccio, Salvatore

2010-01-01T23:59:59.000Z

118

Quantum interference of electromagnetic fields from remote quantum memories  

E-Print Network (OSTI)

We observe quantum, Hong-Ou-Mandel, interference of fields produced by two remote atomic memories. High-visibility interference is obtained by utilizing the finite atomic memory time in four-photon delayed coincidence measurements. Interference of fields from remote atomic memories is a crucial element in protocols for scalable generation of multi-node remote qubit entanglement.

T. Chaneliere; D. N. Matsukevich; S. D. Jenkins; S. -Y. Lan; R. Zhao; T. A. B. Kennedy; A. Kuzmich

2006-09-27T23:59:59.000Z

119

Supersymmetric extensions of K field theories  

E-Print Network (OSTI)

We review the recently developed supersymmetric extensions of field theories with non-standard kinetic terms (so-called K field theories) in two an three dimensions. Further, we study the issue of topological defect formation in these supersymmetric theories. Specifically, we find supersymmetric K field theories which support topological kinks in 1+1 dimensions as well as supersymmetric extensions of the baby Skyrme model for arbitrary nonnegative potentials in 2+1 dimensions.

Adam, C; Sanchez-Guillen, J; Wereszczynski, A

2012-01-01T23:59:59.000Z

120

Vortex operators in gauge field theories  

SciTech Connect

Several related aspects of the 't Hooft vortex operator are studied. The current picture of the vacuum of quantum chromodynamics, the idea of dual field theories, and the idea of the vortex operator are reviewed first. The Abelian vortex operator written in terms of elementary fields and the calculation of its Green's functions are considered. A two-dimensional solvable model of a Dirac string is presented. The expression of the Green's functions more neatly in terms of Wu and Yang's geometrical idea of sections is addressed. The renormalization of the Green's functions of two kinds of Abelian looplike operators, the Wilson loop and the vortex operator, is studied; for both operators only an overall multiplicative renormalization is needed. In the case of the vortex this involves a surprising cancellation. Next, the dependence of the Green's functions of the Wilson and 't Hooft operators on the nature of the vacuum is discussed. The cluster properties of the Green's functions are emphasized. It is seen that the vortex operator in a massive Abelian theory always has surface-like clustering. The form of Green's functions in terms of Feynman graphs is the same in Higgs and symmetric phases; the difference appears in the sum over all tadpole trees. Finally, systems having fields in the fundamental representation are considered. When these fields enter only weakly into the dynamics, a vortex-like operator is anticipated. Any such operator can no longer be local looplike, but must have commutators at long range. A U(1) lattice gauge theory with two matter fields, one singly charged (fundamental) and one doubly charged (adjoint), is examined. When the fundamental field is weakly coupled, the expected phase transitions are found. When it is strongly coupled, the operator still appears to be a good order parameter, a discontinuous change in its behavior leads to a new phase transition. 18 figures.

Polchinski, J.

1980-07-01T23:59:59.000Z

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


121

Nuclear Dynamics with Effective Field Theories  

E-Print Network (OSTI)

These are the proceedings of the international workshop on "Nuclear Dynamics with Effective Field Theories" held at Ruhr-Universitaet Bochum, Germany from July 1 to 3, 2013. The workshop focused on effective field theories of low-energy QCD, chiral perturbation theory for nuclear forces as well as few- and many-body physics. Included are a short contribution per talk.

Evgeny Epelbaum; Hermann Krebs

2013-09-05T23:59:59.000Z

122

Nuclear Dynamics with Effective Field Theories  

E-Print Network (OSTI)

These are the proceedings of the international workshop on "Nuclear Dynamics with Effective Field Theories" held at Ruhr-Universitaet Bochum, Germany from July 1 to 3, 2013. The workshop focused on effective field theories of low-energy QCD, chiral perturbation theory for nuclear forces as well as few- and many-body physics. Included are a short contribution per talk.

Epelbaum, Evgeny

2013-01-01T23:59:59.000Z

123

Duality Invariance: From M-theory to Double Field Theory  

E-Print Network (OSTI)

We show how the duality invariant approach to M-theory formulated by Berman and Perry relates to the double field theory proposed by Hull and Zwiebach. In doing so we provide suggestions as to how Ramond fields can be incorporated into the double field theory. We find that the standard dimensional reduction procedure has a duality invariant (doubled) analogue in which the gauge fields of the doubled Kaluza-Klein ansatz encode the Ramond potentials. We identify the internal gauge index of these gauge fields with a spinorial index of O(d,d).

Daniel C. Thompson

2011-06-20T23:59:59.000Z

124

Lattice gas models derived from effective field theory  

E-Print Network (OSTI)

We start from a low-energy effective field theory for interacting fermions on the lattice and expand in the hopping parameter to derive the nearest-neighbor interactions for a lattice gas model. In this model the renormalization of couplings for different lattice spacings is inherited from the effective field theory, systematic errors can be estimated a priori, and the breakdown of the lattice gas model description at low temperatures can be understood quantitatively. We apply the lattice gas method to neutron matter and compare with results from a recent quantum simulation.

Matthew Hamilton; Iyam Lynch; Dean Lee

2004-12-03T23:59:59.000Z

125

Topological field theory of dynamical systems  

SciTech Connect

Here, it is shown that the path-integral representation of any stochastic or deterministic continuous-time dynamical model is a cohomological or Witten-type topological field theory, i.e., a model with global topological supersymmetry (Q-symmetry). As many other supersymmetries, Q-symmetry must be perturbatively stable due to what is generically known as non-renormalization theorems. As a result, all (equilibrium) dynamical models are divided into three major categories: Markovian models with unbroken Q-symmetry, chaotic models with Q-symmetry spontaneously broken on the mean-field level by, e.g., fractal invariant sets (e.g., strange attractors), and intermittent or self-organized critical (SOC) models with Q-symmetry dynamically broken by the condensation of instanton-antiinstanton configurations (earthquakes, avalanches, etc.) SOC is a full-dimensional phase separating chaos and Markovian dynamics. In the deterministic limit, however, antiinstantons disappear and SOC collapses into the 'edge of chaos.' Goldstone theorem stands behind spatio-temporal self-similarity of Q-broken phases known under such names as algebraic statistics of avalanches, 1/f noise, sensitivity to initial conditions, etc. Other fundamental differences of Q-broken phases is that they can be effectively viewed as quantum dynamics and that they must also have time-reversal symmetry spontaneously broken. Q-symmetry breaking in non-equilibrium situations (quenches, Barkhausen effect, etc.) is also briefly discussed.

Ovchinnikov, Igor V. [Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California 90095-1594 (United States)

2012-09-15T23:59:59.000Z

126

New Results in Topological Field Theory and Abelian Gauge Theory  

E-Print Network (OSTI)

These are the lecture notes of a set of lectures delivered at the 1995 Trieste summer school in June. I review some recent work on duality in four dimensional Maxwell theory on arbitrary four manifolds, as well as a new set of topological invariants known as the Seiberg-Witten invariants. Much of the necessary background material is given, including a crash course in topological field theory, cohomology of manifolds, topological gauge theory and the rudiments of four manifold theory. My main hope is to wet the readers appetite, so that he or she will wish to read the original works and perhaps to enter this field.

George Thompson

1995-11-06T23:59:59.000Z

127

The spinor field theory of the photon  

E-Print Network (OSTI)

I introduce a spinor field theory for the photon. The three-dimensional vector electromagnetic field and the four-dimensional vector potential are components of this spinor photon field. A spinor equation for the photon field is derived from Maxwell's equations,the relations between the electromagnetic field and the four-dimensional vector potential, and the Lorentz gauge condition. The covariant quantization of free photon field is done, and only transverse photons are obtained. The vacuum energy divergence does not occur in this theory. A covariant "positive frequency" condition is introduced for separating the photon field from its complex conjugate in the presence of the electric current and charge.

Ruo Peng Wang

2011-09-15T23:59:59.000Z

128

Concept of Classical and Quantum Free Acoustic Field  

E-Print Network (OSTI)

The concept of classical and quantum free acoustic (FA) field is theoretically considered. The equations of the free acoustic field are derived. They coincide in the mathematical form with Maxwell equations for the free electromagnetic (EM) field. It is accentuated, that the equations in the mathematical form of Maxwell equations for the free EM-field are universal equations of the Nature. They describe any free complex-vector physical field, vector-functions of which are analytical functions. In the case of a free acoustic field, it seems to be the strong indication taking into account the quantum Fermi liquid model of EM-field leading to the existence of phonons, accompanying the process of a photon formation, that FA-field and free EM-field are the display of the single united field, both the components of which can propagate simultaneously [however, with different velocities], for instance, in weakly absorbing media. The theory proposed can be the theoretical basis for the practical realization of superconducting states at high temperature in the materials with the strong interaction of electrons with acoustic field phonons and with microwave photons in magnetic resonance conditions.

Dmitri Yerchuck; Felix Borovik; Alla Dovlatova; Andrey Alexandrov

2013-12-26T23:59:59.000Z

129

Distillability and positivity of partial transposes in general quantum field systems  

E-Print Network (OSTI)

Criteria for distillability, and the property of having a positive partial transpose, are introduced for states of general bipartite quantum systems. The framework is sufficiently general to include systems with an infinite number of degrees of freedom, including quantum fields. We show that a large number of states in relativistic quantum field theory, including the vacuum state and thermal equilibrium states, are distillable over subsystems separated by arbitrary spacelike distances. These results apply to any quantum field model. It will also be shown that these results can be generalized to quantum fields in curved spacetime, leading to the conclusion that there is a large number of quantum field states which are distillable over subsystems separated by an event horizon.

Rainer Verch; Reinhard F. Werner

2004-03-11T23:59:59.000Z

130

EPR Paradox, Locality and Completeness of Quantum Theory  

Science Conference Proceedings (OSTI)

The quantum theory (QT) and new stochastic approaches have no deterministic prediction for a single measurement or for a single time?series of events observed for a trapped ion

M. Kupczynski

2007-01-01T23:59:59.000Z

131

Formulating Quantum Theory as a Causally Neutral Theory of Bayesian Inference  

E-Print Network (OSTI)

Quantum theory can be viewed as a generalization of classical probability theory, but the analogy as it has been developed so far is not complete. Classical probability theory is independent of causal structure, whereas the conventional quantum formalism requires causal structure to be fixed in advance. In this paper, we develop the formalism of quantum conditional states, which unifies the description of experiments involving two systems at a single time with the description of those involving a single system at two times. The analogies between quantum theory and classical probability theory are expressed succinctly within the formalism and it unifies the mathematical description of distinct concepts, such as ensemble preparation procedures, measurements, and quantum dynamics. We introduce a quantum generalization of Bayes' theorem and the associated notion of Bayesian conditioning. Conditioning a quantum state on a classical variable is the correct rule for updating quantum states in light of classical data, regardless of the causal relationship between the classical variable and the quantum degrees of freedom, but it does not include the projection postulate as a special case. We show that previous arguments that projection is the quantum generalization of conditioning are based on misleading analogies. Since our formalism is causally neutral, conditioning provides a unification of the predictive and retrodictive formalisms for prepare-and-measure experiments and leads to an elegant derivation of the set of states that a system can be "steered" to by making measurements on a remote system.

M. S. Leifer; R. W. Spekkens

2011-07-29T23:59:59.000Z

132

Supersymmetric K field theories and defect structures  

E-Print Network (OSTI)

We construct supersymmetric K field theories (i.e., theories with a non-standard kinetic term) in 1+1 and 2+1 dimensions such that the bosonic sector just consists of a nonstandard kinetic term plus a potential. Further, we study the possibility of topological defect formation in these supersymmetric models. Finally, we consider more general supersymmetric K field theories where, again, topological defects exist in some cases.

Adam, C; Sanchez-Guillen, J; Wereszczynski, A

2011-01-01T23:59:59.000Z

133

Chiral field theory of 0{sup -+} glueball  

Science Conference Proceedings (OSTI)

A chiral field theory of 0{sup -+} glueball is presented. The Lagrangian of this theory is constructed by adding a 0{sup -+} glueball field to a successful Lagrangian of the chiral field theory of pseudoscalar, vector, and axial-vector mesons. The couplings between the pseodoscalar glueball field and the mesons are revealed via a U(1) anomaly. Quantitative study of the physical processes of the 0{sup -+} glueball of m=1.405 GeV is presented. The theoretical predictions can be used to identify the 0{sup -+} glueball.

Li Bingan [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)

2010-06-01T23:59:59.000Z

134

On the Higgs mechanism and the gauge field theory  

E-Print Network (OSTI)

As laboratory experiments for the detection of particles with non-zero rest masses forming the dark matter do not give positive results we offer once more to turn the attention upon the neutrinos background of the Universe. If the neutrinos background has the temperature 2 K, then direct observations of particles are impossible ones and only their high density allows hope for the success indirect observations. In consequence of this the field theory is constructed as the maximum plausible reduction of the Feynman formulation of the quantum theory displaying experiment data adequately.

V. M. Koryukin

2008-01-04T23:59:59.000Z

135

BPS solitons in Lifshitz field theories  

E-Print Network (OSTI)

Lorentz-invariant scalar field theories in d+1 dimensions with second-order derivative terms are unable to support static soliton solutions that are both finite in energy and stable for d>2, a result known as Derrick's theorem. Lifshitz theories, which introduce higher-order spatial derivatives, need not obey Derrick's theorem. We construct stable, finite-energy, static soliton solutions in Lifshitz scalar field theories in 3+1 dimensions with dynamical critical exponent z=2. We exhibit three generic types: non-topological point defects, topological point defects, and topological strings. We focus mainly on Lifshitz theories that are defined through a superpotential and admit BPS solutions. These kinds of theories are the bosonic sectors of supersymmetric theories derived from the stochastic dynamics of a scalar field theory in one higher dimension. If nature obeys a Lifshitz field theory in the ultraviolet, then the novel topological defects discussed here may exist as relics from the early universe. Their discovery would prove that standard field theory breaks down at short distance scales.

Archil Kobakhidze; Jayne E. Thompson; Raymond R. Volkas

2010-10-06T23:59:59.000Z

136

Thermal Correlation Functions of Twisted Quantum Fields  

E-Print Network (OSTI)

We derive the thermal correlators for twisted quantum fields on noncommutative spacetime. We show that the thermal expectation value of the number operator is same as in commutative spacetime, but that higher correlators are sensitive to the noncommutativity parameters $\\theta^{\\mu\

Basu, Prasad; Vaidya, Sachindeo

2010-01-01T23:59:59.000Z

137

Lifshitz field theories with SDiff symmetries  

E-Print Network (OSTI)

We consider Lifshitz field theories with a dynamical critical exponent z equal to the dimension of space d and with a large group of base space symmetries, concretely space coordinate transformations with unit determinant ("Special Diffeomorphisms"). The field configurations of the theories considered may have the topology of skyrmions, vortices or monopoles, although we focus our detailed investigations on skyrmions. The resulting Lifshitz field theories have a BPS bound and exact soliton solutions saturating the bound, as well as time-dependent topological Q-ball solutions. Finally, we investigate the U(1) gauged versions of the Lifshitz field theories coupled to a Chern-Simons gauge field, where the BPS bound and soliton solutions saturating the bound continue to exist.

Adam, C; Sanchez-Guillen, J; Wereszczynski, A

2012-01-01T23:59:59.000Z

138

A New Lorentz Violating Nonlocal Field Theory From String-Theory  

E-Print Network (OSTI)

29] J. Polchinski, String theory. Vol. 2: SuperstringNonlocal Field Theory From String-Theory Ori J. GanorNonlocal Field Theory From String-Theory Ori J. Ganor ?

Ganor, Ori J.

2009-01-01T23:59:59.000Z

139

Quantum and semiclassical theories of chemical reaction rates  

DOE Green Energy (OSTI)

A rigorous quantum mechanical theory (and a semiclassical approximation thereto) is described for calculating chemical reaction rates ``directly``, i.e., without having to solve the complete state-to-state reactive scattering problem. The approach has many vestiges of transition state theory, for which it may be thought of as the rigorous generalization.

Miller, W.H. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.

1995-09-01T23:59:59.000Z

140

The quantum systems control and the optimal control theory  

E-Print Network (OSTI)

Mathematical theory of the quantum systems control is based on some ideas of the optimal control theory. These ideas are developed here as applied to these systems. The results obtained meet the deficiencies in the basis and algorithms of the control synthesis and expand the application of these methods.

V. F. Krotov

2008-04-21T23:59:59.000Z

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


141

The Quantum Challenge in Concept Theory and Natural Language Processing  

E-Print Network (OSTI)

The mathematical formalism of quantum theory has been successfully used in human cognition to model decision processes and to deliver representations of human knowledge. As such, quantum cognition inspired tools have improved technologies for Natural Language Processing and Information Retrieval. In this paper, we overview the quantum cognition approach developed in our Brussels team during the last two decades, specifically our identification of quantum structures in human concepts and language, and the modeling of data from psychological and corpus-text-based experiments. We discuss our quantum-theoretic framework for concepts and their conjunctions/disjunctions in a Fock-Hilbert space structure, adequately modeling a large amount of data collected on concept combinations. Inspired by this modeling, we put forward elements for a quantum contextual and meaning-based approach to information technologies in which 'entities of meaning' are inversely reconstructed from texts, which are considered as traces of these entities' states.

Diederik Aerts; Jan Broekaert; Sandro Sozzo; Tomas Veloz

2013-06-12T23:59:59.000Z

142

The genesis of the quantum theory of the chemical bond  

E-Print Network (OSTI)

An historical overview is given of the relevant steps that allowed the genesis of the quantum theory of the chemical bond, starting from the appearance of the new quantum mechanics and following later developments till approximately 1931. General ideas and some important details are discussed concerning molecular spectroscopy, as well as quantum computations for simple molecular systems performed within perturbative and variational approaches, for which the Born-Oppenheimer method provided a quantitative theory accounting for rotational, vibrational and electronic states. The novel concepts introduced by the Heitler-London theory, complemented by those underlying the method of the molecular orbitals, are critically analyzed along with some of their relevant applications. Further improvements in the understanding of the nature of the chemical bond are also considered, including the ideas of one-electron and three-electron bonds introduced by Pauling, as well as the generalizations of the Heitler-London theory ...

Esposito, S

2013-01-01T23:59:59.000Z

143

The flux theory of gravitation XVIII: macro and quantum gravity, cosmo waves and applications  

Science Conference Proceedings (OSTI)

This paper explains, for the first time, recent and old astonishing phenomena based on reports from the Hubble in light of the flux theory of gravitation (FTG). Among the astonishing phenomena and their explanation are the following: (1) Accelerated ... Keywords: convertor, cosmic dust, cosmic shock waves, dark matter, energy field, fractal, gamma ray burst, macro and quantum gravity, primum, superstring

E. E. Escultura

2003-07-01T23:59:59.000Z

144

Nuclear clusters with Halo Effective Field Theory  

E-Print Network (OSTI)

After a brief discussion of effective field theory applied to nuclear clusters, I present the aspect of Coulomb interactions, with applications to low-energy alpha-alpha and nucleon-alpha scattering.

Higa, Renato

2008-01-01T23:59:59.000Z

145

Nuclear clusters with Halo Effective Field Theory  

E-Print Network (OSTI)

After a brief discussion of effective field theory applied to nuclear clusters, I present the aspect of Coulomb interactions, with applications to low-energy alpha-alpha and nucleon-alpha scattering.

Renato Higa

2008-09-30T23:59:59.000Z

146

Effective field theories for inclusive B decays  

E-Print Network (OSTI)

In this thesis, we study inclusive decays of the B meson. These allow one to determine CKM elements precisely and to search for physics beyond the Standard Model. We use the framework of effective field theories, in ...

Lee, Keith S. M. (Keith Seng Mun)

2006-01-01T23:59:59.000Z

147

From insulator to quantum Hall liquid at low magnetic fields  

E-Print Network (OSTI)

We have performed low-temperature transport measurements on a GaAs twodimensional electron system at low magnetic fields. Multiple temperatureindependent points and accompanying oscillations are observed in the longitudinal resistivity between the low-field insulator and the quantum Hall liquid. The amplitudes of these oscillations can be well described by conventional Shubnikov-de Haas theory, and our experimental results therefore support the existence of an intermediate metallic regime between the low-field insulator and quantum Hall liquid. 1 Two-dimensional (2D) phase transitions have attracted a great deal of interest recently [111]. To date, despite many existing experimental and theoretical studies on 2D phase transitions, there are still some interesting but unresolved issues. In particular, it is still under debate whether a direct transition from an insulator (I) to a high Landau level filling factor (? ? 3) quantum Hall (QH) state at low magnetic fields B is a genuine phase transition. Experimentally, a single approximately temperature (T)-independent point in

Tsai-yu Huanga; C. -t. Lianga; Gil-ho Kimb; C. F. Huangc; Chao-ping Huanga

2006-01-01T23:59:59.000Z

148

Corrections to gauge theories in effective quantum gravity with a cutoff  

E-Print Network (OSTI)

We calculate the lowest order quantum gravity contributions to QED beta function in an effective field theory picture with a momentum cutoff. We use a recently proposed 4 dimensional improved momentum cutoff that preserves gauge and Lorentz symmetries. We find that there is non-vanishing quadratic contribution to the photon 2-point function but that does not lead to the running of the original coupling after renormalization. We argue that gravity cannot turn gauge theories asymptotically free.

G. Cynolter; E. Lendvai

2013-07-17T23:59:59.000Z

149

Real-Vector-Space Quantum Theory with a Universal Quantum Bit  

E-Print Network (OSTI)

We explore a model of the world based on real-vector-space quantum theory. In our model the familiar complex phase appearing in quantum states is replaced by a single binary object that we call the ubit, which is not localized and which can interact with any object in the world. Ordinary complex-vector-space quantum theory can be recovered from this model if we simply impose a certain restriction on the sets of allowed measurements and transformations (Stueckelberg's rule), but in this paper we try to obtain the standard theory, or a close approximation to it, without invoking such a restriction. We look particularly at the effective theory that applies to a subsystem when the ubit is interacting with a much larger environment. In a certain limit it turns out that the ubit-environment interaction has the effect of enforcing Stueckelberg's rule automatically, and we obtain a one-parameter family of effective theories--modifications of standard quantum theory--that all satisfy this rule. The one parameter is the ratio s/omega, where s quantifies the strength of the ubit's interaction with the rest of the world and omega is the ubit's rotation rate. We find that when this parameter is small but not zero, the effective theory is similar to standard quantum theory but is characterized by spontaneous decoherence of isolated systems.

Antoniya Aleksandrova; Victoria Borish; William K. Wootters

2012-10-16T23:59:59.000Z

150

Some Aspects of Supersymmetric Field Theories with Minimal Length and Maximal Momentum  

E-Print Network (OSTI)

We consider a real scalar field and a Majorana fermion field to construct a supersymmetric quantum theory of free fermion fields based on the deformed Heisenberg algebra $[x,p]=i\\hbar\\big(1-\\beta p+2\\beta^{2}p^{2}\\big)$, where $\\beta $ is a deformation parameter. We present a deformed supersymmetric algebra in the presence of minimal length and maximal momentum.

Nozari, Kourosh; Balef, F Rezaee

2013-01-01T23:59:59.000Z

151

Finite temperature field theory and phase transitions  

E-Print Network (OSTI)

We review different aspects of field theory at zero and finite temperature, related to the theory of phase transitions. We discuss different renormalization conditions for the effective potential at zero temperature, emphasizing in particular the MS-bar renormalization scheme. Finite temperature field theory is discussed in the real and imaginary time formalisms, showing their equivalence in simple examples. Bubble nucleation by thermal tunneling, and the subsequent development of the phase transition is described in some detail. Some attention is also devoted to the breakdown of the perturbative expansion and the infrared problem in the finite temperature field theory. Finally the application to baryogenesis at the electroweak phase transition is done in the Standard Model and in the Minimal Supersymmetric Standard Model. In all cases we have translated the condition of not washing out any previously generated baryon asymmetry by upper bounds on the Higgs mass.

Mariano Quiros

1999-01-14T23:59:59.000Z

152

Theory Of Alkyl Terminated Silicon Quantum Dots  

DOE Green Energy (OSTI)

We have carried out a series of ab-initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed surfaces a complete alkyl passivation is possible, steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. In addition, our calculations show that steric repulsion may have a dominant effect in determining the surface structure, and eventually the stability of alkyl passivated clusters, with results dependent on the length of the carbon chain. Alkyl passivation weakly affects optical gaps of silicon quantum dots, while it substantially decreases ionization potentials and electron affinities and affect their excited state properties. On the basis of our results we propose that alkyl terminated quantum dots may be size selected taking advantage of the change in ionization potential as a function of the cluster size.

Reboredo, F; Galli, G

2004-08-19T23:59:59.000Z

153

Variational Multi-Time Green's Functions for Nonequilibrium Quantum Fields  

E-Print Network (OSTI)

The time-dependent variational principle proposed by Balian and Veneroni is used to provide the best approximation to the generating functional for multi-time Green's functions of a set of (bosonic) observables $Q_{\\mu)$. By suitably restricting the trial spaces, the computation of the two-time Green's function, obtained by a second order expansion in the sources, is considerably simplified. This leads to a tractable formalism suited to quantum fields out of equilibrium. We propose an illustration on the finite temperature ${\\bf\\Phi^4}$ theory in curved space and coupled to gravity.

Mohamed Benarous

1997-10-07T23:59:59.000Z

154

Chiral effective field theory and nuclear forces  

E-Print Network (OSTI)

We review how nuclear forces emerge from low-energy QCD via chiral effective field theory. The presentation is accessible to the non-specialist. At the same time, we also provide considerable detailed information (mostly in appendices) for the benefit of researchers who wish to start working in this field.

Machleidt, R

2011-01-01T23:59:59.000Z

155

D-branes and string field theory  

E-Print Network (OSTI)

In this thesis we study the D-brane physics in the context of Witten's cubic string field theory. We compute first few terms the low energy effective action for the non-abelian gauge field A, from Witten's action. We show ...

Sigalov, Ilya

2006-01-01T23:59:59.000Z

156

Dynamic field theory and embodied communication  

Science Conference Proceedings (OSTI)

Dynamical Field Theory is a neurally based approach to embodied and situated cognition, in which information is represented in continuous activation fields defined over metric spaces. The temporal evolution of activation patterns under the influence ... Keywords: embodied cognition, modelling, neural dynamics, turn taking

Yulia Sandamirskaya; Gregor Schner

2006-04-01T23:59:59.000Z

157

Towards a K-theory description of quantum hair  

Science Conference Proceedings (OSTI)

The first steps towards a proposal for a description of the quantum hair in 4D supersymmetric black holes in string Calabi-Yau (CY) compactifications are given. The quantum hair consisting of electric and magnetic fractional charges in black holes are derived from periods of the CY's torsion cycles. In the process a K-theory interpretation of the quantum hair in terms of the Atiyah-Hirzebruch spectral sequence is carried out. Finally, the same procedure is considered for torsion cycles of certain generalized CY's threefolds such as half-flat manifolds.

Garcia-Compean, H.; Loaiza-Brito, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del I.P.N., P.O. Box 14-740, 07000, Mexico D.F (Mexico); Departamento de Fisica, Universidad de Guanajuato, C.P. 37150, Leon, Guanajuato (Mexico)

2012-08-24T23:59:59.000Z

158

Conformal field theory on affine Lie groups  

Science Conference Proceedings (OSTI)

Working directly on affine Lie groups, we construct several new formulations of the WZW model, the gauged WZW model, and the generic affine-Virasoro action. In one formulation each of these conformal field theories (CFTs) is expressed as a one-dimensional mechanical system whose variables are coordinates on the affine Lie group. When written in terms of the affine group element, this formulation exhibits a two-dimensional WZW term. In another formulation each CFT is written as a two-dimensional field theory, with a three- dimensional WZW term, whose fields are coordinates on the affine group. On the basis of these equivalent formulations, we develop a translation dictionary in which the new formulations on the affine Lie group are understood as mode formulations of the conventional formulations on the Lie group. Using this dictionary, we also express each CFT as a three-dimensional field theory on the Lie group with a four-dimensional WZW term. 36 refs.

Clubok, K.S.

1996-04-01T23:59:59.000Z

159

Quantum interference effect and electric field domain formation in quantum well infrared photodetectors  

E-Print Network (OSTI)

Quantum interference effect and electric field domain formation in quantum well infrared April 1995 An observation of quantum interference effect in photocurrent spectra of a weakly coupled bound-to-continuum multiple quantum well photodetector is reported. This effect persists even at high

160

Time Evolution in the external field problem of Quantum Electrodynamics  

E-Print Network (OSTI)

A general problem of quantum field theories is the fact that the free vacuum and the vacuum for an interacting theory belong to different, non-equivalent representations of the canonical (anti-)commutation relations. In the external field problem of QED, we encounter this problem in the form that the Dirac time evolution for an external field with non-vanishing magnetic components will not satisfy the Shale-Stinespring condition, known to be necessary and sufficient for the existence of an implementation on the fermionic Fock space. Therefore, a second quantization of the time evolution in the usual way is impossible. In this thesis, we present several rigorous approaches to QED with time-dependent, external fields and analyze in what sense a time evolution can exist in the second quantized theory. We study different constructions of the fermionic Fock space and prove their equivalence. We study and compare the results of Deckert et. al. (2010), where the time evolution is realized as unitary transformations ...

Lazarovici, Dustin

2013-01-01T23:59:59.000Z

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


161

Quantum-mechanical theory of optomechanical Brillouin cooling  

SciTech Connect

We analyze how to exploit Brillouin scattering of light from sound for the purpose of cooling optomechanical devices and present a quantum-mechanical theory for Brillouin cooling. Our analysis shows that significant cooling ratios can be obtained with standard experimental parameters. A further improvement of cooling efficiency is possible by increasing the dissipation of the optical anti-Stokes resonance.

Tomes, Matthew; Bahl, Gaurav; Carmon, Tal [Department of Electrical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Marquardt, Florian [Institut fuer Theoretische Physik, Universitaet Erlangen-Nuernberg, Staudtstrasse 7, D-91058 Erlangen (Germany); Max Planck Institute for the Science of Light, Guenther-Scharowsky-Strasse 1/Bau 24, D-91058 Erlangen (Germany)

2011-12-15T23:59:59.000Z

162

Quantum Theory of Fast Chemical Reactions  

SciTech Connect

The aims of the research under this grant were to develop a theoretical understanding and predictive abiility for a variety of processes occurring in the gas phase. These included bimolecular chemical exchange reactions, photodissociation, predissociation resonances, unimolecular reactions and recombination reactions. In general we assumed a knowledge, from quantum chemistry, of the interactions of the atoms and molecular fragments involved. Our focus was primarily on the accurate (quantum) dynamics of small molecular systems. This has been important for many reactions related to combustion and atmospheric chemistry involving light atom transfer reactions and, for example, resonances in dissociation and recombination reactions. The rates of such reactions, as functions of temperature, internal states, and radiation (light), are fundamental for generating models of overall combustion processes. A number of new approaches to these problems were developed inclluding the use of discrete variable representations (DVR's) for evaluating rate constants with the flux-flux correlation approach, finite range approaches to exact quantum scattering calculations, energy selected basis representations, transition state wave packet approaches and improved semiclassical approaches. These (and others) were applied to a number of reactive systems and molecular systems of interest including (many years ago) the isotopic H + H2 exchange reactions, the H2 + OH (and H + H2O) systems, Ozone resonances, van der Waals molecule reactions, etc. A total of 7 graduate students, and 5 post-doctoral Research Associates were supported, at least in part, under this grant and seven papers were published with a total of 10 external collaborators. The majority of the 36 publications under this grant were supported entirely by DOE.

John C. Light

2007-07-30T23:59:59.000Z

163

Gravity quantized: Loop quantum gravity with a scalar field  

Science Conference Proceedings (OSTI)

...''but we do not have quantum gravity.'' This phrase is often used when analysis of a physical problem enters the regime in which quantum gravity effects should be taken into account. In fact, there are several models of the gravitational field coupled to (scalar) fields for which the quantization procedure can be completed using loop quantum gravity techniques. The model we present in this paper consists of the gravitational field coupled to a scalar field. The result has similar structure to the loop quantum cosmology models, except that it involves all the local degrees of freedom of the gravitational field because no symmetry reduction has been performed at the classical level.

Domagala, Marcin; Kaminski, Wojciech [Instytut Fizyki Teoretycznej, Uniwersytet Warszawski, ul. Hoza 69, 00-681 Warszawa (Warsaw), Polska (Poland) (Poland); Giesel, Kristina [Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstrasse 2, 85748 Garching (Germany); Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Lewandowski, Jerzy [Instytut Fizyki Teoretycznej, Uniwersytet Warszawski, ul. Hoza 69, 00-681 Warszawa (Warsaw), Polska (Poland) (Poland); Institute for Gravitation and the Cosmos, Physics Department, Penn State, University Park, Pennsylvania 16802 (United States)

2010-11-15T23:59:59.000Z

164

Symmetry analysis for anisotropic field theories  

Science Conference Proceedings (OSTI)

The purpose of this paper is to study with the help of Noether's theorem the symmetries of anisotropic actions for arbitrary fields which generally depend on higher order spatial derivatives, and to find the corresponding current densities and the Noether charges. We study in particular scale invariance and consider the cases of higher derivative extensions of the scalar field, electrodynamics and Chern-Simons theory.

Parra, Lorena; Vergara, J. David [Instituto de Ciencias Nucleares, UNAM, Circuito Exterior s/n, Ciudad Universitaria. Delg. Coyoacan. C.P. 04510 Mexico DF (Mexico)

2012-08-24T23:59:59.000Z

165

N=2 supersymmetric gauge theories and quantum integrable systems  

E-Print Network (OSTI)

We study N=2 supersymmetric gauge theories on the product of a two-sphere and a cylinder. We show that the low-energy dynamics of a BPS sector of such a theory is described by a quantum integrable system, with the Planck constant set by the inverse of the radius of the sphere. If the sphere is replaced with a hemisphere, then our system reduces to an integrable system of the type studied by Nekrasov and Shatashvili. In this case we establish a correspondence between the effective prepotential of the gauge theory and the Yang-Yang function of the integrable system.

Yuan Luo; Meng-Chwan Tan; Junya Yagi

2013-10-02T23:59:59.000Z

166

N=2 supersymmetric gauge theories and quantum integrable systems  

E-Print Network (OSTI)

We study N=2 supersymmetric gauge theories on the product of a two-sphere and a cylinder. We show that the low-energy dynamics of a BPS sector of such a theory is described by a quantum integrable system, with the Planck constant set by the inverse of the radius of the sphere. If the sphere is replaced with a hemisphere, then our system reduces to an integrable system of the type studied by Nekrasov and Shatashvili. In this case we establish a correspondence between the effective prepotential of the gauge theory and the Yang-Yang function of the integrable system.

Luo, Yuan; Yagi, Junya

2013-01-01T23:59:59.000Z

167

Valley splitting theory of SiGe/Si/SiGe quantum wells Mark Friesen,1,  

E-Print Network (OSTI)

Valley splitting theory of SiGe/Si/SiGe quantum wells Mark Friesen,1, * Sucismita Chutia,1 Charles an effective mass theory for SiGe/Si/SiGe quantum wells, with an emphasis on calculating the valley splitting. The theory introduces a valley coupling parameter vv which encapsulates the physics of the quantum well

Sheridan, Jennifer

168

Book Review of Stephen L. Adler's, "Quantum theory as an emergent phenomenon."  

E-Print Network (OSTI)

In Stephen Adler's book, "Quantum theory as an emergent phenomenon," the author starts from a classical mechanics structure and "derives" the formalism of quantum theory, together with wave function collapse dynamics, the latter providing the interpretation of quantum theory. A detailed outline of the author's argument is presented in this book review.

Philip Pearle

2006-02-07T23:59:59.000Z

169

Effective field theory as a limit of R-matrix theory for light nuclear reactions  

E-Print Network (OSTI)

We study the zero channel radius limit of Wigner's R-matrix theory for two cases, and show that it corresponds to non-relativistic effective quantum field theory. We begin with the simple problem of single-channel n-p elastic scattering in the 1S0 channel. The dependence of the R matrix width and level energy on the channel radius, "a" for fixed scattering length a0 and effective range r0 is determined. It is shown that these quantities have a simple pole for a critical value of the channel radius. The 3H(d,n)4He reaction cross section, analyzed with a two-channel effective field theory in the previous paper, is then examined using a two-channel, single-level R-matrix parametrization. The resulting S matrix is shown to be identical in these two representations in the limit that R-matrix channel radii are taken to zero. This equivalence is established by giving the relationship between the low-energy constants of the effective field theory (couplings and mass) and the R-matrix parameters (reduced width amplitudes and level energy). An excellent three-parameter fit to the observed astrophysical factor S is found for "unphysical" values of the reduced widths.

Gerald M. Hale; Lowell S. Brown; Mark W. Paris

2013-08-01T23:59:59.000Z

170

Superconducting Circuits for Quantum Simulation of Dynamical Gauge Fields  

E-Print Network (OSTI)

We describe a superconducting-circuit lattice design for the implementation and simulation of dynamical lattice gauge theories. We illustrate our proposal by analyzing a one-dimensional U(1) quantum-link model, where superconducting qubits play the role of matter fields on the lattice sites and the gauge fields are represented by two coupled microwave resonators on each link between neighboring sites. A detailed analysis of a minimal experimental protocol for probing the physics related to string breaking effects shows that despite the presence of decoherence in these systems, distinctive phenomena from condensed-matter and high-energy physics can be visualized with state-of-the-art technology in small superconducting-circuit arrays.

D. Marcos; P. Rabl; E. Rico; P. Zoller

2013-06-07T23:59:59.000Z

171

Topological methods in quantum gravity.  

E-Print Network (OSTI)

??The main technical problem with background independent approaches to quantum gravity is inapplicability of standard quantum field theory methods. New methods are needed which would (more)

Starodubtsev, Artem

2005-01-01T23:59:59.000Z

172

Rigged Hilbert space formalism as an extended mathematical formalism for quantum systems. II. Transformation theory in nonrelativistic quantum mechanics  

Science Conference Proceedings (OSTI)

Results of a previous paper are used to obtain a rigorous mathematical formulation of the transformation theory of nonrelativistic quantum mechanics within the framework of rigged Hilbert spaces.

O. Melsheimer

1974-01-01T23:59:59.000Z

173

The graph representation approach to topological field theory in 2 + 1 dimensions  

SciTech Connect

An alternative definition of topological quantum field theory in 2+1 dimensions is discussed. The fundamental objects in this approach are not gauge fields as in the usual approach, but non-local observables associated with graphs. The classical theory of graphs is defined by postulating a simple diagrammatic rule for computing the Poisson bracket of any two graphs. The theory is quantized by exhibiting a quantum deformation of the classical Poisson bracket algebra, which is realized as a commutator algebra on a Hilbert space of states. The wavefunctions in this graph representation'' approach are functionals on an appropriate set of graphs. This is in contrast to the usual connection representation'' approach in which the theory is defined in terms of a gauge field and the wavefunctions are functionals on the space of flat spatial connections modulo gauge transformations.

Martin, S.P.

1991-02-01T23:59:59.000Z

174

Matrix Product States for Lattice Field Theories  

E-Print Network (OSTI)

The term Tensor Network States (TNS) refers to a number of families of states that represent different ans\\"atze for the efficient description of the state of a quantum many-body system. Matrix Product States (MPS) are one particular case of TNS, and have become the most precise tool for the numerical study of one dimensional quantum many-body systems, as the basis of the Density Matrix Renormalization Group method. Lattice Gauge Theories (LGT), in their Hamiltonian version, offer a challenging scenario for these techniques. While the dimensions and sizes of the systems amenable to TNS studies are still far from those achievable by 4-dimensional LGT tools, Tensor Networks can be readily used for problems which more standard techniques, such as Markov chain Monte Carlo simulations, cannot easily tackle. Examples of such problems are the presence of a chemical potential or out-of-equilibrium dynamics. We have explored the performance of Matrix Product States in the case of the Schwinger model, as a widely used ...

Bauls, Mari Carmen; Cirac, J Ignacio; Jansen, Karl; Saito, Hana

2013-01-01T23:59:59.000Z

175

Nuclear effective field theory on the lattice  

E-Print Network (OSTI)

In the low-energy region far below the chiral symmetry breaking scale (which is of the order of 1 GeV) chiral perturbation theory provides a model-independent approach for quantitative description of nuclear processes. In the two- and more-nucleon sector perturbation theory is applicable only at the level of an effective potential which serves as input in the corresponding dynamical equation. To deal with the resulting many-body problem we put chiral effective field theory (EFT) on the lattice. Here we present the results of our lattice EFT study up to next-to-next-to-leading order in the chiral expansion. Accurate description of two-nucleon phase-shifts and ground state energy ratio of dilute neutron matter up to corrections of higher orders shows that lattice EFT is a promising tool for a quantitative description of low-energy few- and many-body systems.

Hermann Krebs; Bugra Borasoy; Evgeny Epelbaum; Dean Lee; Ulf-G. Mei ner

2008-10-01T23:59:59.000Z

176

Nonviolent information transfer from black holes: a field theory parameterization  

E-Print Network (OSTI)

A candidate parameterization is introduced, in an effective field theory framework, for the quantum information transfer from a black hole that is necessary to restore unitarity. This in particular allows description of the effects of such information transfer in the black hole atmosphere, for example seen by infalling observers. In the presence of such information transfer, it is shown that infalling observers need not experience untoward violence. Moreover, the presence of general moderate-frequency couplings to field modes with high angular momenta offers a mechanism to enhance information transfer rates, commensurate with the increased energy flux, when a string is introduced to "mine" a black hole. Generic such models for nonviolent information transfer predict extra energy flux from a black hole, beyond that of Hawking.

Giddings, Steven B

2013-01-01T23:59:59.000Z

177

Massive Type II in Double Field Theory  

E-Print Network (OSTI)

We provide an extension of the recently constructed double field theory formulation of the low-energy limits of type II strings, in which the RR fields can depend simultaneously on the 10-dimensional space-time coordinates and linearly on the dual winding coordinates. For the special case that only the RR one-form of type IIA carries such a dependence, we obtain the massive deformation of type IIA supergravity due to Romans. For T-dual configurations we obtain a `massive' but non-covariant formulation of type IIB, in which the 10-dimensional diffeomorphism symmetry is deformed by the mass parameter.

Olaf Hohm; Seung Ki Kwak

2011-08-24T23:59:59.000Z

178

Molecular mean field theory for liquid water  

E-Print Network (OSTI)

Attractive bonding interactions between molecules typically have inherent conservation laws which influence the statistical properties of such systems in terms of corresponding sum rules. We considered lattice water as an example and enunciated the consequences of the sum rule through a general computational procedure called "Molecular mean field" theory. Fluctuations about mean field are computed and many of the liquid properties have been deduced and compared with Monte Carlo simulation, molecular dynamics and experimental results. Large correlation lengths are seen to be a consequence of the sum rule in liquid phase. Long range Coulomb interactions are shown to have minor effects on our results.

Jampa Maruthi Pradeep Kanth; Ramesh Anishetty

2010-04-09T23:59:59.000Z

179

Loop Quantum Theory Applied to Biology and Nonlinear Whole Biology  

E-Print Network (OSTI)

The loop quantum theory, which constitutes a very small discontinuous space, as new method is applied to biology. The model of protein folding and lungs is proposed. In the model, some known results are used, and four approximate conclusions are obtained: their structures are quantized, their space regions are finite, various singularities correspond to folding and crossed points, and different types of catastrophe exist. Further, based on the inseparability and correlativity of the biological systems, the nonlinear whole biology is proposed, and four basic hypotheses are formed. It may unify reductionism and holism, structuralism and functionalism. Finally, the medical meaning of the theory is discussed briefly.

Yi-Fang Chang

2008-01-02T23:59:59.000Z

180

Quantum theory of cold bosonic atoms in optical lattices  

SciTech Connect

Ultracold atoms in optical lattices undergo a quantum phase transition from a superfluid to a Mott insulator as the lattice potential depth is increased. We describe an approximate theory of interacting bosons in optical lattices which provides a qualitative description of both superfluid and insulator states. The theory is based on a change of variables in which the boson coherent state amplitude is replaced by an effective potential which promotes phase coherence between different number states on each lattice site. It is illustrated here by applying it to uniform and fully frustrated lattice cases but is simple enough that it can be applied to spatially inhomogeneous lattice systems.

Tilahun, Dagim [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Department of Physics, Texas State University, San Marcos, Texas 78666 (United States); Duine, R. A. [Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, NL-3584 CE Utrecht (Netherlands); MacDonald, A. H. [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

2011-09-15T23:59:59.000Z

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


181

Theory of ground state factorization in quantum cooperative systems  

E-Print Network (OSTI)

We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows to determine rigorously existence, location, and exact form of separable ground states in a large variety of, generally non-exactly solvable, spin models belonging to different universality classes. The theory applies to translationally invariant systems, irrespective of spatial dimensionality, and for spin-spin interactions of arbitrary range.

Giampaolo, S M; Illuminati, F

2008-01-01T23:59:59.000Z

182

Time Series, Stochastic Processes and Completeness of Quantum Theory  

Science Conference Proceedings (OSTI)

Most of physical experiments are usually described as repeated measurements of some random variables. Experimental data registered by on?line computers form time series of outcomes. The frequencies of different outcomes are compared with the probabilities provided by the algorithms of quantum theory (QT). In spite of statistical predictions of QT a claim was made that it provided the most complete description of the data and of the underlying physical phenomena. This claim could be easily rejected if some fine structures

2011-01-01T23:59:59.000Z

183

Theory of ground state factorization in quantum cooperative systems  

E-Print Network (OSTI)

We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows to determine rigorously existence, location, and exact form of separable ground states in a large variety of, generally non-exactly solvable, spin models belonging to different universality classes. The theory applies to translationally invariant systems, irrespective of spatial dimensionality, and for spin-spin interactions of arbitrary range.

S. M. Giampaolo; G. Adesso; F. Illuminati

2008-04-01T23:59:59.000Z

184

Conservation laws. Generation of physical fields. Principles of field theories  

E-Print Network (OSTI)

In the paper the role of conservation laws in evolutionary processes, which proceed in material systems (in material media) and lead to generation of physical fields, is shown using skew-symmetric differential forms. In present paper the skew-symmetric differential forms on deforming (nondifferentiable) manifolds were used in addition to exterior forms, which have differentiable manifolds as a basis. Such skew-symmetric forms (which were named evolutionary ones since they possess evolutionary properties), as well as the closed exterior forms, describe the conservation laws. But in contrast to exterior forms, which describe conservation laws for physical fields, the evolutionary forms correspond to conservation laws for material systems. The evolutionary forms possess an unique peculiarity, namely, the closed exterior forms are obtained from these forms. It is just this that enables one to describe the process of generation of physical fields, to disclose connection between physical fields and material systems and to resolve many problems of existing field theories.

L. I. Petrova

2007-04-19T23:59:59.000Z

185

A New Look at the Position Operator in Quantum Theory  

E-Print Network (OSTI)

The postulate that coordinate and momentum representations are related to each other by the Fourier transform has been accepted from the beginning of quantum theory by analogy with classical electrodynamics. As a consequence, an inevitable effect in standard theory is the wave packet spreading (WPS) of the photon coordinate wave function in directions perpendicular to the photon momentum. This leads to the following paradoxes: if the major part of photons emitted by stars are in wave packet states (what is the most probable scenario) then we should see not separate stars but only an almost continuous background from all stars; no anisotropy of the CMB radiation should be observable; data on gamma-ray bursts, signals from directional radio antennas (in particular, in experiments on Shapiro delay) and signals from pulsars show no signs of WPS. In addition, a problem arises why there are no signs of WPS for protons in the LHC ring. We argue that the above postulate is based neither on strong theoretical arguments nor on experimental data and propose a new consistent definition of the position operator. Then WPS in directions perpendicular to the particle momentum is absent and the paradoxes are resolved. Different components of the new position operator do not commute with each other and, as a consequence, there is no wave function in coordinate representation. Implications of the results for entanglement, quantum locality and the problem of time in quantum theory are discussed.

Felix M. Lev

2012-07-04T23:59:59.000Z

186

Time Evolution in the external field problem of Quantum Electrodynamics  

E-Print Network (OSTI)

A general problem of quantum field theories is the fact that the free vacuum and the vacuum for an interacting theory belong to different, non-equivalent representations of the canonical (anti-)commutation relations. In the external field problem of QED, we encounter this problem in the form that the Dirac time evolution for an external field with non-vanishing magnetic components will not satisfy the Shale-Stinespring condition, known to be necessary and sufficient for the existence of an implementation on the fermionic Fock space. Therefore, a second quantization of the time evolution in the usual way is impossible. In this thesis, we present several rigorous approaches to QED with time-dependent, external fields and analyze in what sense a time evolution can exist in the second quantized theory. We study different constructions of the fermionic Fock space and prove their equivalence. We study and compare the results of Deckert et. al. (2010), where the time evolution is realized as unitary transformations between time-varying Fock spaces, with those of Langmann and Mickelsson (1996), who construct a "renormalization" for the time evolution and present a method to fix the phase of the second quantized scattering operator by parallel transport in a principle fibre bundle over the restricted, general linear group acting on the fermionic Fock space. We provide rigorous proof for the fact that the second quantization by parallel transport preserves causality. These findings seem to refute claims made in Scharf (1995) that the phase of the second quantized S-matrix is essentially determined by the requirement of causality. We propose a simple solution to the problem of gauge anomalies in the procedure of Langmann and Mickelsson, showing that the second quantization of the scattering operator can be made gauge-invariant by using a suitable class of renormalizations.

Dustin Lazarovici

2013-10-07T23:59:59.000Z

187

Progress in quantum electrodynamics theory of highly charged ions  

E-Print Network (OSTI)

Recent progress in quantum electrodynamics (QED) calculations of highly charged ions is reviewed. The theoretical predictions for the binding energies, the hyperfine splittings, and the g factors are presented and compared with available experimental data. Special attention is paid to tests of bound-state QED at strong field regime. Future prospects for tests of QED at the strongest electric and magnetic fields as well as for determination of the fine structure constant and the nuclear magnetic moments with heavy ions are discussed.

A. V. Volotka; D. A. Glazov; G. Plunien; V. M. Shabaev

2013-09-20T23:59:59.000Z

188

Density-gradient theory: a macroscopic approach to quantum confinement and tunneling in semiconductor devices  

Science Conference Proceedings (OSTI)

Density-gradient theory provides a macroscopic approach to modeling quantum transport that is particularly well adapted to semiconductor device analysis and engineering. After some introductory observations, the basis of the theory in macroscopic and ... Keywords: Continuum, Density-gradient, Electron transport, Quantum confinement, Quantum tunneling, Semiconductor device simulation, Thermodynamics

M. G. Ancona

2011-06-01T23:59:59.000Z

189

Sustainable entanglement farming from a quantum field  

E-Print Network (OSTI)

We propose a protocol by which entanglement can be extracted repeatedly from a quantum field. In analogy with prior work on entanglement harvesting, we call this protocol entanglement farming. It consists of successively sending pairs of unentangled particles through an optical cavity. Using non-perturbative Gaussian methods, we show that in certain generic circumstances this protocol drives the cavity field towards a non-thermal metastable state. This state of the cavity is such that successive pairs of unentangled particles sent through the cavity will reliably emerge significantly entangled. We calculate thermodynamic aspects of the harvesting process, such as energies and entropies, and also the long-term behavior beyond the few-mode approximation. Significant for possible experimental realizations is the fact that this entangling fixed point state of the cavity is reached largely independently of the initial state in which the cavity was prepared. Our results suggest that reliable entanglement farming on the basis of such a fixed point state should be possible also in various other experimental settings, namely with the to-be-entangled particles replaced by arbitrary qudits and with the cavity replaced by a suitable reservoir system.

Eduardo Martin-Martinez; Eric G. Brown; William Donnelly; Achim Kempf

2013-09-04T23:59:59.000Z

190

Instantaneous spatially local projective measurements are consistent in a relativistic quantum field  

SciTech Connect

Suppose the postulate of measurement in quantum mechanics can be extended to quantum field theory; then a local projective measurement at some moment on an object locally coupled with a relativistic quantum field will result in a projection or collapse of the wavefunctional of the combined system defined on the whole time-slice associated with the very moment of the measurement, if the relevant degrees of freedom have nonzero correlations. This implies that the wavefunctionals in the same Hamiltonian system but defined in different reference frames would collapse on different time-slices passing through the same local event where the measurement was done. Are these post-measurement states consistent with each other? We illustrate that the quantum states of the Raine-Sciama-Grove detector-field system started with the same initial Gaussian state defined on the same initial time-slice, then collapsed by the measurements on the pointlike detectors on different time-slices in different frames, will evolve to the same state of the combined system up to a coordinate transformation when compared on the same final time-slice. Such consistency is guaranteed by the spatial locality of interactions and the general covariance in a relativistic system, together with the spatial locality of measurements and the linearity of quantum dynamics in its quantum theory. - Highlights: Black-Right-Pointing-Pointer Spatially local quantum measurements in detector-field models are studied. Black-Right-Pointing-Pointer Local quantum measurement collapses the wavefunctional on the whole time-slice. Black-Right-Pointing-Pointer In different frames wavefunctionals of a field would collapse on different time-slices. Black-Right-Pointing-Pointer States collapsed by the same measurement will be consistent on the same final slice.

Lin, Shih-Yuin, E-mail: sylin156@gmail.com

2012-12-15T23:59:59.000Z

191

Lattice field theory simulations of graphene  

E-Print Network (OSTI)

We discuss the Monte Carlo method of simulating lattice field theories as a means of studying the low-energy effective theory of graphene. We also report on simulational results obtained using the Metropolis and Hybrid Monte Carlo methods for the chiral condensate, which is the order parameter for the semimetal-insulator transition in graphene, induced by the Coulomb interaction between the massless electronic quasiparticles. The critical coupling and the associated exponents of this transition are determined by means of the logarithmic derivative of the chiral condensate and an equation-of-state analysis. A thorough discussion of finite-size effects is given, along with several tests of our calculational framework. These results strengthen the case for an insulating phase in suspended graphene, and indicate that the semimetal-insulator transition is likely to be of second order, though exhibiting neither classical critical exponents, nor the predicted phenomenon of Miransky scaling.

Joaqun E. Drut; Timo A. Lhde

2009-01-06T23:59:59.000Z

192

Quantum critical transport, duality, and M-theory  

E-Print Network (OSTI)

We consider charge transport properties of 2+1 dimensional conformal field theories at non-zero temperature. For theories with only Abelian U(1) charges, we describe the action of particle-vortex duality on the hydrodynamic-to-collisionless crossover function: this leads to powerful functional constraints for self-dual theories. For the n=8 supersymmetric, SU(N) Yang-Mills theory at the conformal fixed point, exact hydrodynamic-to-collisionless crossover functions of the SO(8) R-currents can be obtained in the large N limit by applying the AdS/CFT correspondence to M-theory. In the gravity theory, fluctuating currents are mapped to fluctuating gauge fields in the background of a black hole in 3+1 dimensional anti-de Sitter space. The electromagnetic self-duality of the 3+1 dimensional theory implies that the correlators of the R-currents obey a functional constraint similar to that found from particle-vortex duality in 2+1 dimensional Abelian theories. Thus the 2+1 dimensional, superconformal Yang Mills theory obeys a "holographic self duality" in the large N limit, and perhaps more generally.

Christopher P. Herzog; Pavel Kovtun; Subir Sachdev; Dam Thanh Son

2007-01-05T23:59:59.000Z

193

Multiparty quantum protocols for assisted entanglement distillation  

Science Conference Proceedings (OSTI)

Quantum information theory is a multidisciplinary field whose objective is to understand what happens when information is stored in the state of a quantum system. Quantum mechanics provides us with a new resource, called quantum entanglement, ...

Nicolas Dutil

2011-01-01T23:59:59.000Z

194

SO(4,1) Yang-Mills theory of quantum gravity  

E-Print Network (OSTI)

The search for a quantum theory of gravity has become one of the most well-known problems in theoretical physics. Problems quantizing general relativity because it is not renormalizable have led to a search for a new theory of gravity that, while still agreeing with measured observations, is renormalizable. In this paper, a spin-1 Yang-Mills force theory with a SO(4,1) or {\\em de Sitter} group symmetry is developed. By deriving the standard geodesic equation and the first post-Newtonian approximation equations, it is shown that this theory, coupled to Dirac fields, predicts all N-body and light observations of gravitational phenomena to within experimental accuracy. Furthermore, because of the separation of gauge covariance from coordinate diffeomorphism, the theory satisfies the strong equivalence principle while maintaining a Minkowski coordinate metric. Cosmology is also briefly addressed: Vacuum energy is the most common explanation for the accelerating expansion of the universe but suffers from the drawback that any reasonable prediction of it is 120 orders of magnitude too large. The de Sitter solution to the Einstein Field Equations is an alternative to vacuum energy as an explanation for the accelerating expansion of the universe but only if the universe is approximately a vacuum. The proposed gauge theory, however, avoids both these problems and, cosmologically, the accelerating expansion of the universe is shown as a consequence of the de Sitter group Lie algebra. In addition, with quantized mass, because it is a generic massless, semi-simple Yang-Mills theory, it is mathematically proved to be a perturbatively renormalizable quantum theory of gravity.

Timothy D. Andersen

2010-05-21T23:59:59.000Z

195

Drift estimation from a simple field theory  

SciTech Connect

Given the outcome of a Wiener process, what can be said about the drift and diffusion coefficients? If the process is stationary, these coefficients are related to the mean and variance of the position displacements distribution. However, if either drift or diffusion are time-dependent, very little can be said unless some assumption about that dependency is made. In Bayesian statistics, this should be translated into some specific prior probability. We use Bayes rule to estimate these coefficients from a single trajectory. This defines a simple, and analytically tractable, field theory.

Mendes, F. M.; Figueiredo, A. [Instituto de Fisica, Universidade de Brasilia, CP: 04455, 70919-970-Brasilia (Brazil)

2008-11-06T23:59:59.000Z

196

Thermal field theories and shifted boundary conditions  

E-Print Network (OSTI)

The analytic continuation to an imaginary velocity of the canonical partition function of a thermal system expressed in a moving frame has a natural implementation in the Euclidean path-integral formulation in terms of shifted boundary conditions. The Poincare' invariance underlying a relativistic theory implies a dependence of the free-energy on the compact length L_0 and the shift xi only through the combination beta=L_0(1+xi^2)^(1/2). This in turn implies that the energy and the momentum distributions of the thermal theory are related, a fact which is encoded in a set of Ward identities among the correlators of the energy-momentum tensor. The latter have interesting applications in lattice field theory: they offer novel ways to compute thermodynamic potentials, and a set of identities to renormalize non-perturbatively the energy-momentum tensor. At fixed bare parameters the shifted boundary conditions also provide a simple method to vary the temperature in much smaller steps than with the standard procedure.

Leonardo Giusti; Harvey B. Meyer

2013-10-29T23:59:59.000Z

197

Thermal field theories and shifted boundary conditions  

E-Print Network (OSTI)

The analytic continuation to an imaginary velocity of the canonical partition function of a thermal system expressed in a moving frame has a natural implementation in the Euclidean path-integral formulation in terms of shifted boundary conditions. The Poincare' invariance underlying a relativistic theory implies a dependence of the free-energy on the compact length L_0 and the shift xi only through the combination beta=L_0(1+xi^2)^(1/2). This in turn implies that the energy and the momentum distributions of the thermal theory are related, a fact which is encoded in a set of Ward identities among the correlators of the energy-momentum tensor. The latter have interesting applications in lattice field theory: they offer novel ways to compute thermodynamic potentials, and a set of identities to renormalize non-perturbatively the energy-momentum tensor. At fixed bare parameters the shifted boundary conditions also provide a simple method to vary the temperature in much smaller steps than with the standard procedur...

Giusti, Leonardo

2013-01-01T23:59:59.000Z

198

Testing axioms for Quantum Mechanics on Probabilistic toy-theories  

E-Print Network (OSTI)

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

Giacomo Mauro D'Ariano; Alessandro Tosini

2009-11-29T23:59:59.000Z

199

Bosonic Loop Diagrams as Perturbative Solutions of the Classical Field Equations in $\\phi^4$-Theory  

E-Print Network (OSTI)

Solutions of the classical $\\phi^4$-theory in Minkowski space-time are analyzed in a perturbation expansion in the nonlinearity. Using the language of Feynman diagrams, the solution of the Cauchy problem is expressed in terms of tree diagrams which involve the retarded Green's function and have one outgoing leg. In order to obtain general tree diagrams, we set up a "classical measurement process" in which a virtual observer of a scattering experiment modifies the field and detects suitable energy differences. By adding a classical stochastic background field, we even obtain all loop diagrams. The expansions are compared with the standard Feynman diagrams of the corresponding quantum field theory.

Finster, Felix

2012-01-01T23:59:59.000Z

200

Molecular quantum mechanical observers, symmetry, and string theory  

E-Print Network (OSTI)

The paper \\cite{Dance0601} tentatively suggested a physical picture that might underlie string theories. The string parameters $\\tau $ and $\\sigma_i $ were interpreted as spacetime dimensions which a simple quantum mechanical observer can observe, while symmetries of the relevant observer states could limit the observability of other dimensions. An atomic observer was the focus of the discussion. The present paper extends the discussion of\\cite{Dance0601} to molecular observers, including the nature of some common molecular bonds and their symmetries.

M. Dance

2010-11-29T23:59:59.000Z

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


201

Book Review: "Quantum Theory as an Emergent Phenomenon", by Stephen L. Adler  

E-Print Network (OSTI)

This is a book review of the book: "Quantum Theory as an Emergent Phenomenon", by Stephen L. Adler (Cambridge University Press - 2004)

A. Bassi

2005-04-28T23:59:59.000Z

202

Holographic Theory of Accelerated Observers, the S-matrix, and the Emergence of Effective Field Theory  

E-Print Network (OSTI)

We present a theory of accelerated observers in the formalism of holographic space time, and show how to define the analog of the Unruh effect for a one parameter set of accelerated observers in a causal diamond in Minkowski space. The key fact is that the formalism splits the degrees of freedom in a large causal diamond into particles and excitations on the horizon. The latter form a large heat bath for the particles, and different Hamiltonians, describing a one parameter family of accelerated trajectories, have different couplings to the bath. We argue that for a large but finite causal diamond the Hamiltonian describing a geodesic observer has a residual coupling to the bath and that the effect of the bath is finite over the long time interval in the diamond. We find general forms of the Hamiltonian, which guarantee that the horizon degrees of freedom will decouple in the limit of large diamonds, leaving over a unitary evolution operator for particles, with an asymptotically conserved energy. That operator converges to the S-matrix in the infinite diamond limit. The S-matrix thus arises from integrating out the horizon degrees of freedom, in a manner reminiscent of, but distinct from, Matrix Theory. We note that this model for the S-matrix implies that Quantum Gravity, as opposed to quantum field theory, has a natural adiabatic switching off of the interactions. We argue that imposing Lorentz invariance on the S-matrix is natural, and guarantees super-Poincare invariance in the HST formalism. Spatial translation invariance is seen to be the residuum of the consistency conditions of HST.

Tom Banks; Willy Fischler

2013-01-24T23:59:59.000Z

203

Toward theory of quantum Hall effect in graphene  

E-Print Network (OSTI)

We analyze a gap equation for the propagator of Dirac quasiparticles and conclude that in graphene in a magnetic field, the order parameters connected with the quantum Hall ferromagnetism dynamics and those connected with the magnetic catalysis dynamics necessarily coexist (the latter have the form of Dirac masses and correspond to excitonic condensates). This feature of graphene could lead to important consequences, in particular, for the existence of gapless edge states. Solutions of the gap equation corresponding to recently experimentally discovered novel plateaus in graphene in strong magnetic fields are described.

E. V. Gorbar; V. P. Gusynin; V. A. Miransky

2007-10-18T23:59:59.000Z

204

Quantum rotor theory of spinor condensates in tight traps  

Science Conference Proceedings (OSTI)

In this work, we theoretically construct exact mappings of many-particle bosonic systems onto quantum rotor models. In particular, we analyze the rotor representation of spinor Bose-Einstein condensates. In a previous work [R. Barnett et al., Phys. Rev. A 82, 031602(R) (2010)] it was shown that there is an exact mapping of a spin-one condensate of fixed particle number with quadratic Zeeman interaction onto a quantum rotor model. Since the rotor model has an unbounded spectrum from above, it has many more eigenstates than the original bosonic model. Here we show that for each subset of states with fixed spin F{sub z}, the physical rotor eigenstates are always those with the lowest energy. We classify three distinct physical limits of the rotor model: the Rabi, Josephson, and Fock regimes. The last regime corresponds to a fragmented condensate and is thus not captured by the Bogoliubov theory. We next consider the semiclassical limit of the rotor problem and make connections with the quantum wave functions through the use of the Husimi distribution function. Finally, we describe how to extend the analysis to higher-spin systems and derive a rotor model for the spin-two condensate. Theoretical details of the rotor mapping are also provided here.

Barnett, Ryan; Hui, Hoi-Yin; Lin, Chien-Hung; Sau, Jay D.; Das Sarma, S. [Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States)

2011-02-15T23:59:59.000Z

205

Integrable Conformal Field Theory - A Case Study  

Science Conference Proceedings (OSTI)

Over the last decades, 2-dimensional conformal field theory has been developed into a powerful tool that has been applied to problems in diverse branches of physics and mathematics. Models are usually solved algebraically by exploiting certain infinite dimensional symmetries. But the presence of sufficient world-sheet symmetry is a rather exceptional feature, one that is e.g. not present for curved string backgrounds at generic points in moduli space. In this note I review some recent work which aims at computing spectra of conformal sigma models without spectrum generating symmetries. Our main results are illustrated at the example of complex projective superspace (C) P{sup N-1|N}. This note is based on several publications with C. Candu, T. Creutzig, V. Mitev, T. Quella and H. Saleur.

Schomerus, Volker [DESY Hamburg, Theory Group, Notkestrasse 85, D-22607 Hamburg (Germany)

2010-06-17T23:59:59.000Z

206

Power counting regime of chiral effective field theory and beyond.  

Science Conference Proceedings (OSTI)

Chiral effective field theory ({chi}EFT) complements numerical simulations of quantum chromodynamics (QCD) on a space-time lattice. It provides a model-independent formalism for connecting lattice simulation results at finite volume and a variety of quark masses to the physical world. The asymptotic nature of the chiral expansion places the focus on the first few terms of the expansion. Thus, knowledge of the power-counting regime (PCR) of {chi}EFT, where higher-order terms of the expansion may be regarded as negligible, is as important as knowledge of the expansion itself. Through the consideration of a variety of renormalization schemes and associated parameters, techniques to identify the PCR where results are independent of the renormalization scheme are established. The nucleon mass is considered as a benchmark for illustrating this general approach. Because the PCR is small, the numerical simulation results are also examined to search for the possible presence of an intrinsic scale which may be used in a nonperturbative manner to describe lattice simulation results outside of the PCR. Positive results that improve on the current optimistic application of chiral perturbation theory ({chi}PT) beyond the PCR are reported.

Hall, J. M.M.; Leinweber, D. B.; Young, R. D.; Physics; Univ. of Adelaide

2010-08-10T23:59:59.000Z

207

Power counting regime of chiral effective field theory and beyond  

Science Conference Proceedings (OSTI)

Chiral effective field theory ({chi}EFT) complements numerical simulations of quantum chromodynamics (QCD) on a space-time lattice. It provides a model-independent formalism for connecting lattice simulation results at finite volume and a variety of quark masses to the physical world. The asymptotic nature of the chiral expansion places the focus on the first few terms of the expansion. Thus, knowledge of the power-counting regime (PCR) of {chi}EFT, where higher-order terms of the expansion may be regarded as negligible, is as important as knowledge of the expansion itself. Through the consideration of a variety of renormalization schemes and associated parameters, techniques to identify the PCR where results are independent of the renormalization scheme are established. The nucleon mass is considered as a benchmark for illustrating this general approach. Because the PCR is small, the numerical simulation results are also examined to search for the possible presence of an intrinsic scale which may be used in a nonperturbative manner to describe lattice simulation results outside of the PCR. Positive results that improve on the current optimistic application of chiral perturbation theory ({chi}PT) beyond the PCR are reported.

Hall, J. M. M.; Leinweber, D. B. [Special Research Centre for the Subatomic Structure of Matter (CSSM), School of Chemistry and Physics, University of Adelaide, SA 5005 (Australia); Young, R. D. [Special Research Centre for the Subatomic Structure of Matter (CSSM), School of Chemistry and Physics, University of Adelaide, SA 5005 (Australia); Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

2010-08-01T23:59:59.000Z

208

Quantum Chromodynamics  

E-Print Network (OSTI)

Quantum chromodynamics is the quantum gauge field theory that describes the strong interactions. This article reviews the basic structure, successes and challenges of quantum chromodynamics as it manifests itself at short and long distances, including the concepts of asymptotic freedom, confinement and infrared safety.

George Sterman

2005-12-27T23:59:59.000Z

209

Quantum Exact Non-Abelian Vortices in Non-relativistic Theories  

E-Print Network (OSTI)

Non-Abelian vortices arise when a non-Abelian global symmetry is exact in the ground state but spontaneously broken in the vicinity of their cores. In this case, there appear (non-Abelian) Nambu-Goldstone (NG) modes confined and propagating along the vortex. In relativistic theories, the Coleman-Mermin-Wagner theorem forbids the existence of a spontaneous symmetry breaking, or a long-range order, in 1+1 dimensions: quantum corrections restore the symmetry along the vortex and the NG modes acquire a mass gap. We show that in non-relativistic theories NG modes with quadratic dispersion relation confined on a vortex can remain gapless at quantum level. We provide a concrete and experimentally realizable example of a three-component Bose-Einstein condensate with U(1) x U(2) symmetry. We first show, at the classical level, the existence of S^3 = S^1 |x S^2 (S^1 fibered over S^2) NG modes associated to the breaking U(2) -> U(1) on vortices, where S^1 and S^2 correspond to type I and II NG modes, respectively. We then show, by using a Bethe ansatz technique, that the U(1) symmetry is restored, while the SU(2) symmery remains broken non-pertubatively at quantum level. Accordingly, the U(1) NG mode turns into a c=1 conformal field theory, the Tomonaga-Luttinger liquid, while the S^2 NG mode remains gapless, describing a ferromagnetic liquid. This allows the vortex to be genuinely non-Abelian at quantum level.

Muneto Nitta; Shun Uchino; Walter Vinci

2013-11-21T23:59:59.000Z

210

Quantum kinetic theory model of a continuous atom laser  

E-Print Network (OSTI)

We investigate the feasible limits for realising a continuously evaporated atom laser with high-temperature sources. A plausible scheme for realising a truly continuous atom laser is to outcouple atoms from a partially condensed Bose gas, whilst continuously reloading the system with non-condensed thermal atoms and performing evaporative cooling. Here we use quantum kinetic theory to model this system and estimate feasible limits for the operation of such a scheme. For sufficiently high temperatures, the figure of merit for the source is shown to be the phase-space flux. The dominant process limiting the usage of sources with low phase-space flux is the three-body loss of the condensed gas. We conclude that certain double-magneto-optical trap (MOT) sources may produce substantial mean condensate numbers through continuous evaporation, and provide an atom laser source with a narrow linewidth and reasonable flux.

G. R. Dennis; Matthew J. Davis; J. J. Hope

2010-11-24T23:59:59.000Z

211

Magnetic field switching in parallel quantum dots  

E-Print Network (OSTI)

We show that the Coulomb blockade in parallel dots pierced by magnetic flux $\\Phi$ completely blocks the resonant current for any value of $\\Phi$ except for integer multiples of the flux quantum $\\Phi_0$. This non-analytic (switching) dependence of the current on $\\Phi$ arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when $\\Phi\\to n\\Phi_0$.

Feng Li; Xin-Qi Li; Wei-Min Zhang; S. A. Gurvitz

2008-03-11T23:59:59.000Z

212

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

E-Print Network (OSTI)

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

O. N. Golubjeva; A. D. Sukhanov

2013-03-25T23:59:59.000Z

213

Effective Field Theory of Fractional Quantized Hall Nematics  

SciTech Connect

We present a Landau-Ginzburg theory for a fractional quantized Hall nematic state and the transition to it from an isotropic fractional quantum Hall state. This justifies Lifshitz-Chern-Simons theory - which is shown to be its dual - on a more microscopic basis and enables us to compute a ground state wave function in the symmetry-broken phase. In such a state of matter, the Hall resistance remains quantized while the longitudinal DC resistivity due to thermally-excited quasiparticles is anisotropic. We interpret recent experiments at Landau level filling factor {nu} = 7/3 in terms of our theory.

Mulligan, Michael; /MIT, LNS; Nayak, Chetan; /Station Q, UCSB; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC

2012-06-06T23:59:59.000Z

214

Magnetic field switching in parallel quantum dots  

E-Print Network (OSTI)

We show that the Coulomb blockade in parallel dots pierced by magnetic flux $\\Phi$ completely blocks the resonant current for any value of $\\Phi$ except for integer multiples of the flux quantum $\\Phi_0$. This non-analytic (switching) dependence of the current on $\\Phi$ arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when $\\Phi\\to n\\Phi_0$. This current switch effect can find application in nano-circuit devices.

Li, Feng; Zhang, Wei-Min; Gurvitz, S A

2008-01-01T23:59:59.000Z

215

The Solar pp and hep Processes in Effective Field Theory  

E-Print Network (OSTI)

The strategy of modern effective field theory is exploited to pin down accurately the flux $S$ factors for the $pp$ and $hep$ processes in the Sun. The technique used is to combine the high accuracy established in few-nucleon systems of the "standard nuclear physics approach" (SNPA) and the systematic power counting of chiral perturbation theory (ChPT) into a consistent effective field theory framework. Using highly accurate wave functions obtained in the SNPA and working to \

T. -S. Park; K. Kubodera; D. -P. Min; M. Rho

2001-08-21T23:59:59.000Z

216

A Holographic Quantum Critical Point at Finite Magnetic Field and Finite Density  

E-Print Network (OSTI)

We analyze the phase diagram of N=4 supersymmetric Yang-Mills theory with fundamental matter in the presence of a background magnetic field and nonzero baryon number. We identify an isolated quantum critical point separating two differently ordered finite density phases. The ingredients that give rise to this transition are generic in a holographic setup, leading us to conjecture that such critical points should be rather common. In this case, the quantum phase transition is second order with mean-field exponents. We characterize the neighborhood of the critical point at small temperatures and identify some signatures of a new phase dominated by the critical point. We also identify the line of transitions between the finite density and zero density phases. The line is completely determined by the mass of the lightest charged quasiparticle at zero density. Finally, we measure the magnetic susceptibility and find hints of fermion condensation at large magnetic field.

Kristan Jensen; Andreas Karch; Ethan G. Thompson

2010-02-11T23:59:59.000Z

217

Ionisation of a quantum dot by electric fields  

Science Conference Proceedings (OSTI)

We have derived analytical formulas for differential and total ionisation probabilities of a two-dimensional quantum dot by a constant electric field. In the adiabatic approximation, we have calculated the probability of this process in the field of a plane electromagnetic wave and in a superposition of constant and alternating electric fields. The imaginary-time method is used to obtain the momentum distribution of the ionisation probability of a bound system by an intense field generated by a superposition of parallel constant and alternating electric fields. The total probability of the process per unit time is calculated with exponential accuracy. The dependence of the results obtained on the characteristic parameters of the problem is investigated. (laser applications and other topics in quantum electronics)

Eminov, P A; Gordeeva, S V

2012-08-31T23:59:59.000Z

218

Indecomposability parameters in chiral Logarithmic Conformal Field Theory  

E-Print Network (OSTI)

Work of the last few years has shown that the key algebraic features of Logarithmic Conformal Field Theories (LCFTs) are already present in some finite lattice systems (such as the XXZ spin-1/2 chain) before the continuum limit is taken. This has provided a very convenient way to analyze the structure of indecomposable Virasoro modules and to obtain fusion rules for a variety of models such as (boundary) percolation etc. LCFTs allow for additional quantum numbers describing the fine structure of the indecomposable modules, and generalizing the `b-number' introduced initially by Gurarie for the c=0 case. The determination of these indecomposability parameters has given rise to a lot of algebraic work, but their physical meaning has remained somewhat elusive. In a recent paper, a way to measure b for boundary percolation and polymers was proposed. We generalize this work here by devising a general strategy to compute matrix elements of Virasoro generators from the numerical analysis of lattice models and their continuum limit. The method is applied to XXZ spin-1/2 and spin-1 chains with open (free) boundary conditions. They are related to gl(n+m|m) and osp(n+2m|2m)-invariant superspin chains and to nonlinear sigma models with supercoset target spaces. These models can also be formulated in terms of dense and dilute loop gas. We check the method in many cases where the results were already known analytically. Furthermore, we also confront our findings with a construction generalizing Gurarie's, where logarithms emerge naturally in operator product expansions to compensate for apparently divergent terms. This argument actually allows us to compute indecomposability parameters in any logarithmic theory. A central result of our study is the construction of a Kac table for the indecomposability parameters of the logarithmic minimal models LM(1,p) and LM(p,p+1).

Romain Vasseur; Jesper Lykke Jacobsen; Hubert Saleur

2011-03-16T23:59:59.000Z

219

High energy processes using effective field theories  

E-Print Network (OSTI)

free theory, so the low-energy matrix element contributionout. 5. The low-energy matrix element, which gives unity,energy parton scattering, and can be included by treating all the equations below as matrix

Kelley, Randall Scott

2009-01-01T23:59:59.000Z

220

String field theory and tachyon dynamics  

E-Print Network (OSTI)

In this thesis we present some works done during my doctoral studies. These results focus on two directions. The first one is motivated by tachyon dynamics in open string theory. We calculate the stress tensors for the ...

Yang, Haitang, Ph. D. Massachusetts Institute of Technology

2006-01-01T23:59:59.000Z

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


221

Quantum bundles and quantum interactions  

E-Print Network (OSTI)

A geometric framework for describing quantum particles on a possibly curved background is proposed. Natural constructions on certain distributional bundles (`quantum bundles') over the spacetime manifold yield a quantum ``formalism'' along any 1-dimensional timelike submanifold (a `detector'); in the flat, inertial case this turns out to reproduce the basic results of the usual quantum field theory, while in general it could be seen as a local, ``linearized'' description of the actual physics.

Daniel Canarutto

2005-06-22T23:59:59.000Z

222

On unentangled Gleason theorems for quantum information theory  

E-Print Network (OSTI)

It is shown here that a strengthening of Wallach's Unentangled Gleason Theorem can be obtained by applying results of the present authors on generalised Gleason theorems for quantum multi-measures arising from investigations of quantum decoherence functionals.

Oliver Rudolph; J. D. M. Wright

2000-04-07T23:59:59.000Z

223

Thermal Reservoir coupled to External Field and Quantum Dissipation  

E-Print Network (OSTI)

In the framework of the Caldeira-Leggett model of dissipative quantum mechanics, we investigate the effects of the interaction of the thermal reservoir with an external field. In particular, we discuss how the interaction modifies the conservative dynamics of the central particle, and the mechanism of dissipation. We briefly comment on possible observable consequencies.

Fabrizio Illuminati; Marco Patriarca

1992-07-29T23:59:59.000Z

224

Heavy Quarks, QCD, and Effective Field Theory  

SciTech Connect

The research supported by this OJI award is in the area of heavy quark and quarkonium production, especially the application Soft-Collinear E#11;ective Theory (SCET) to the hadronic production of quarkonia. SCET is an e#11;ffective theory which allows one to derive factorization theorems and perform all order resummations for QCD processes. Factorization theorems allow one to separate the various scales entering a QCD process, and in particular, separate perturbative scales from nonperturbative scales. The perturbative physics can then be calculated using QCD perturbation theory. Universal functions with precise fi#12;eld theoretic de#12;nitions describe the nonperturbative physics. In addition, higher order perturbative QCD corrections that are enhanced by large logarithms can be resummed using the renormalization group equations of SCET. The applies SCET to the physics of heavy quarks, heavy quarkonium, and similar particles.

Thomas Mehen

2012-10-09T23:59:59.000Z

225

Beyond the Quantum Adiabatic Approximation: Adiabatic Perturbation Theory  

E-Print Network (OSTI)

We introduce a perturbative approach to solving the time dependent Schroedinger equation, named adiabatic perturbation theory (APT), whose zeroth order term is the quantum adiabatic approximation. The small parameter in the power series expansion of the time-dependent wave function is the inverse of the time it takes to drive the system's Hamiltonian from the initial to its final form. We review other standard perturbative and non-perturbative ways of going beyond the adiabatic approximation, extending and finding exact relations among them, and also compare the efficiency of those methods against the APT. Most importantly, we determine APT corrections to the Berry phase by use of the Aharonov-Anandan geometric phase. We then solve several time dependent problems allowing us to illustrate that the APT is the only perturbative method that gives the right corrections to the adiabatic approximation. Finally, we propose an experiment to measure the APT corrections to the Berry phase and show, for a particular spin-1/2 problem, that to first order in APT the geometric phase should be two and a half times the (adiabatic) Berry phase.

Gustavo Rigolin; Gerardo Ortiz; Victor Hugo Ponce

2008-07-09T23:59:59.000Z

226

Modern integral equation techniques for quantum reactive scattering theory  

SciTech Connect

Rigorous calculations of cross sections and rate constants for elementary gas phase chemical reactions are performed for comparison with experiment, to ensure that our picture of the chemical reaction is complete. We focus on the H/D+H{sub 2} {yields} H{sub 2}/DH + H reaction, and use the time independent integral equation technique in quantum reactive scattering theory. We examine the sensitivity of H+H{sub 2} state resolved integral cross sections {sigma}{sub v{prime}j{prime},vj}(E) for the transitions (v = 0,j = 0) to (v{prime} = 1,j{prime} = 1,3), to the difference between the Liu-Siegbahn-Truhlar-Horowitz (LSTH) and double many body expansion (DMBE) ab initio potential energy surfaces (PES). This sensitivity analysis is performed to determine the origin of a large discrepancy between experimental cross sections with sharply peaked energy dependence and theoretical ones with smooth energy dependence. We find that the LSTH and DMBE PESs give virtually identical cross sections, which lends credence to the theoretical energy dependence.

Auerbach, S.M.

1993-11-01T23:59:59.000Z

227

Jordan cells in logarithmic limits of conformal field theory  

E-Print Network (OSTI)

It is discussed how a limiting procedure of conformal field theories may result in logarithmic conformal field theories with Jordan cells of arbitrary rank. This extends our work on rank-two Jordan cells. We also consider the limits of certain three-point functions and find that they are compatible with known results. The general construction is illustrated by logarithmic limits of (unitary) minimal models in conformal field theory. Characters of quasi-rational representations are found to emerge as the limits of the associated irreducible Virasoro characters.

Jorgen Rasmussen

2004-06-13T23:59:59.000Z

228

Quantum energy flow in atomic ions moving in magnetic fields  

E-Print Network (OSTI)

Using a combination of semiclassical and recently developed wave packet propagation techniques we find the quantum self-ionization process of highly excited ions moving in magnetic fields which has its origin in the energy transfer from the center of mass to the electronic motion. It obeys a time scale by orders of magnitude larger than the corresponding classical process. Importantly a quantum coherence phenomenon leading to the intermittent behaviour of the ionization signal is found and analyzed. Universal properties of the ionization process are established.

Vladimir Melezhik; Peter Schmelcher

2000-06-07T23:59:59.000Z

229

Generalized Galilean Transformations and the Measurement Problem in the Entropic Dynamics Approach to Quantum Theory  

E-Print Network (OSTI)

Quantum mechanics is an extremely successful and accurate physical theory, yet since its inception, it has been afflicted with numerous conceptual difficulties. The primary subject of this thesis is the theory of entropic quantum dynamics (EQD), which seeks to avoid these conceptual problems by interpreting quantum theory from an informational perspective. We begin by reviewing probability theory as a means of rationally quantifying uncertainties. We then discuss how probabilities can be updated with the method of maximum entropy (ME). We then review some motivating difficulties in quantum mechanics before discussing Caticha's work in deriving quantum theory from the approach of entropic dynamics. After entropic dynamics is introduced, we develop the concepts of symmetries and transformations from an informational perspective. The primary result is the formulation of a symmetry condition that any transformation must satisfy in order to qualify as a symmetry in EQD. We then proceed to apply this condition to the extended Galilean transformation. This transformation is of interest as it exhibits features of both special and general relativity. The transformation yields a gravitational potential that arises from an equivalence of information. We conclude the thesis with a discussion of the measurement problem in quantum mechanics. We discuss the difficulties that arise in the standard quantum mechanical approach to measurement before developing our theory of entropic measurement. In entropic dynamics, position is the only observable. We show how a theory built on this one observable can account for the multitude of measurements present in quantum theory. Furthermore, we show that the Born rule need not be postulated, but can be derived in EQD. Finally, we show how the wave function can be updated by the ME method as the phase is constructed purely in terms of probabilities.

David T. Johnson

2011-05-06T23:59:59.000Z

230

Comparisons and Connections between Mean Field Dynamo Theory and Accretion Disc Theory  

E-Print Network (OSTI)

The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi-analytic mean field theories that distill the essential physics. Mean field dynamo (MFD) theory and alpha-viscosity accretion disc theory exemplify this pursuit. That the latter is a mean field theory is not always made explicit but the combination of turbulence and global symmetry imply such. The more commonly explicit presentation of assumptions in 20th century textbook MFDT has exposed it to arguably more widespread criticism than incurred by 20th century alpha-accretion theory despite complementary weaknesses. In the 21st century however, MFDT has exp...

Blackman, Eric G

2009-01-01T23:59:59.000Z

231

Astrophysical weak-interaction processes and nuclear effective field theory  

E-Print Network (OSTI)

Low-energy nuclear weak-interaction processes play important roles in many astrophysical contexts, and effective field theory is believed to be a highly useful framework for describing these processes in a model-independent manner. I present a brief account of the basic features of the nuclear effective theory approach, and some examples of actual calculations carried out in this method.

K. Kubodera

2004-04-09T23:59:59.000Z

232

Nonlinear field theory with topological solitons: Skyrme models  

E-Print Network (OSTI)

In this talk, we give new insight into one of the best-known nonlinear field theories, the Skyrme model. We present some exact relevant solutions coming from different new versions (gauged BPS baby as well as vector BPS Skyrme models) giving rise to topological solitons, and highlighting the BPS character of the theory.

Adam, C; Sanchez-Guillen, J; Wereszczynski, A

2013-01-01T23:59:59.000Z

233

A simple proof of orientability in colored group field theory  

E-Print Network (OSTI)

In this short note we use results from the theory of crystallizations to prove that color in group field theories garantees orientability of the piecewise linear pseudo-manifolds associated to each graph generated perturbatively. The origin of orientability is the presence of two interaction vertices.

Francesco Caravelli

2010-12-18T23:59:59.000Z

234

More is the Same; Phase Transitions and Mean Field Theories  

E-Print Network (OSTI)

. Dierent phases can be qualitatively dif- ferent in that walking on ice is well within human capacityMore is the Same; Phase Transitions and Mean Field Theories Leo P. Kadano The James Franck in a series which will look at the theory of phase transitions from the perspectives of physics

Ismagilov, Rustem F.

235

Three level constraints on conformal field theories and string models  

Science Conference Proceedings (OSTI)

Simple tree level constraints for conformal field theories which follow from the requirement of crossing symmetry of four-point amplitudes are presented, and their utility for probing general properties of string models is briefly illustrated and discussed. 9 refs.

Lewellen, D.C.

1989-05-01T23:59:59.000Z

236

Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots  

E-Print Network (OSTI)

Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots Sedat Nizamoglu, Pedro Ludwig Hernández-Martínez, Evren Mutlugun, Durmus misfit strains on the band offsets of Zn1-xBexO/ZnO quantum wells: A first-principles analysis J. Appl

Demir, Hilmi Volkan

237

BPS bounds in supersymmetric extensions of K field theories  

E-Print Network (OSTI)

We demonstrate that in the supersymmetric extensions of a class of generalized (or K) field theories introduced recently, the static energy satisfies a BPS bound in each topological sector. Further, the corresponding soliton solutions saturate the bound. We also find strong indications that the BPS bound shows up in the SUSY algebra as a central extension, as is the case in the well-known supersymmetric field theories with standard kinetic terms.

Adam, C; Sanchez-Guillen, J; Wereszczynski, A

2012-01-01T23:59:59.000Z

238

Effective field theory and integrability in two-dimensional Mott transition  

SciTech Connect

Highlights: > Mott transition in 2d lattice fermion model. > 3D integrability out of 2D. > Effective field theory for Mott transition in 2d. > Double Chern-Simons. > d-Density waves. - Abstract: We study the Mott transition in a two-dimensional lattice spinless fermion model with nearest neighbors density-density interactions. By means of a two-dimensional Jordan-Wigner transformation, the model is mapped onto the lattice XXZ spin model, which is shown to possess a quantum group symmetry as a consequence of a recently found solution of the Zamolodchikov tetrahedron equation. A projection (from three to two space-time dimensions) property of the solution is used to identify the symmetry of the model at the Mott critical point as U{sub q}(sl(2)-circumflex)xU{sub q}(sl(2)-circumflex), with deformation parameter q = -1. Based on this result, the low-energy effective field theory for the model is obtained and shown to be a lattice double Chern-Simons theory with coupling constant k = 1 (with the standard normalization). By further employing the effective filed theory methods, we show that the Mott transition that arises is of topological nature, with vortices in an antiferromagnetic array and matter currents characterized by a d-density wave order parameter. We also analyze the behavior of the system upon weak coupling, and conclude that it undergoes a quantum gas-liquid transition which belongs to the Ising universality class.

Bottesi, Federico L. [Facultad de Ingenieria Pontificia Universidad Catolica Argentina, Av. Alicia Moreau de Justo 1500, 1428 Buenos Aires (Argentina); Physics Department, Comision Nacional de Energia Atomica, Av. Libertador 8250, 1429 Buenos Aires (Argentina); Zemba, Guillermo R., E-mail: zemba@tander.cnea.gov.ar [Facultad de Ingenieria Pontificia Universidad Catolica Argentina, Av. Alicia Moreau de Justo 1500, 1428 Buenos Aires (Argentina); Physics Department, Comision Nacional de Energia Atomica, Av. Libertador 8250, 1429 Buenos Aires (Argentina)

2011-08-15T23:59:59.000Z

239

A simple supersymmetric extension of K field theories  

E-Print Network (OSTI)

We continue the investigation of supersymmetric extensions of field theories with a non-standard kinetic term (K field theories) resumed recently. Concretely, for K field theories which allow for kink or compacton solutions in 1+1 dimensions, i.e., for domain walls in a higher-dimensional context, we find a simple supersymmetric extension such that the boson field still has the kink solution, and the field equation for the fermion in the kink background is linear and is solved by the first spatial derivative of the kink, as is the case in the corresponding standard supersymmetric theories. This supersymmetric extension, nevertheless, is peculiar in several aspects. The bosonic part of the supersymmetric Lagrangian is not equal to the original bosonic K field Lagrangian, but the bosonic field equations coincide. Further, the field equation for the bosonic field is produced by the variation of the auxiliary field and vice versa. This observation may be of some independent interest. Finally, the presence of kink...

Adam, C; Sanchez-Guillen, J

2010-01-01T23:59:59.000Z

240

Room-temperature electric-field controlled spin dynamics in ,,110... InAs quantum wells  

E-Print Network (OSTI)

Room-temperature electric-field controlled spin dynamics in ,,110... InAs quantum wells K. C. Halla pseudomagnetic fields exceeding 1 T when only 140 mV is applied across a single quantum well. Using this large­11 and the influence of the Rashba pseudomagnetic fields on the electron spin relaxation time in GaAs quantum wells

Flatte, Michael E.

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


241

Nonlinear relativistic quantum theory of Cherenkov emission of longitudinal Langmuir waves in a plasma  

Science Conference Proceedings (OSTI)

A nonlinear relativistic quantum theory of stimulated Cherenkov emission of longitudinal waves by a relativistic monoenergetic electron beam in a cold isotropic plasma is presented. The theory makes use of a quantum model based on the Klein-Gordon equation. The instability growth rates are obtained in the linear approximation and are shown to go over to the familiar growth rates in the classical limit. The mechanisms for the nonlinear saturation of relativistic Cherenkov beam instabilities are described with allowance for quantum effects, and the corresponding analytic solutions are derived.

Bobylev, Yu. V.; Kuzelev, M. V. [Moscow State University (Russian Federation)

2011-10-15T23:59:59.000Z

242

Questions and Answers - How can I explain the Quantum/Wave theory to my  

NLE Websites -- All DOE Office Websites (Extended Search)

What is a meniscus? What is a meniscus? Previous Question (What is a meniscus?) Questions and Answers Main Index Next Question (What is the sun made from?) What is the sun made from? How can I explain the Quantum/Wave theory to my class? You can't! The folks who have postulated the quantum nature of matter and wave-particle duality, and other quantum theories have trouble explaining it in terms other than mathematical equations. When trying to explain it in conceptual terms, we're asked to accept things that don't make sense, and in some ways, physicists use this as justification that the theory is correct. Anyway, here are a couple ideas for discussing the quantum/wave properties of energy. Until around 1900, when Max Planck developed the idea of quanta, energy had been thought to be a phenomenon of continuous flow - basically waves.

243

Oriented matroid theory and loop quantum gravity in (2+2) and eight dimensions  

E-Print Network (OSTI)

We establish a connection between oriented matroid theory and loop quantum gravity in (2+2) (two time and two space dimensions) and 8-dimensions. We start by observing that supersymmetry implies that the structure constants of the real numbers, complex numbers, quaternions and octonions can be identified with the chirotope concept. This means, among other things, that normed divisions algebras, which are only possible in 1,2, 4 or 8-dimensions, are linked to oriented matroid theory. Therefore, we argue that the possibility for developing loop quantum gravity in 8-dimensions must be taken as important alternative. Moreover, we show that in 4-dimensions, loop quantum gravity theories in the (1+3) or (0+4) signatures are not the only possibilities. In fact, we show that loop quantum gravity associated with the (2+2)-signature may also be an interesting physical structure.

J. A. Nieto

2010-03-24T23:59:59.000Z

244

Quantum simulations of gauge theories with ultracold atoms: local gauge invariance from angular momentum conservation  

E-Print Network (OSTI)

Quantum simulations of High Energy Physics, and especially of gauge theories, is an emerging and exciting direction in quantum simulations. However, simulations of such theories, compared to simulations of condensed matter physics, must satisfy extra restrictions, such as local gauge and Lorentz invariance. In this paper we discuss these special requirements, and present a new method for quantum simulation of lattice gauge theories using ultracold atoms. This method allows to include local gauge invariance as a fundamental symmetry of the atomic Hamiltonian, arising from natural atomic interactions and conservation laws (and not as a property of a low energy sector). This allows us to implement elementary gauge invariant interactions for three lattice gauge theories: compact QED (U(1)), SU(N) and Z_N, which can be used to build quantum simulators in 1+1 dimensions. We also present a new loop method, which uses the elementary interactions as building blocks in the effective construction of quantum simulations for d+1 dimensional lattice gauge theories (d>1), without having to use Gauss's law as a constraint, as in previous proposals. We discuss in detail the quantum simulation of 2+1 dimensional compact QED and provide a numerical proof of principle. The simplicity of the already gauge invariant elementary interactions of this model suggests it may be useful for future experimental realizations.

Erez Zohar; J. Ignacio Cirac; Benni Reznik

2013-03-20T23:59:59.000Z

245

Field theory of pion-nucleus interactions  

SciTech Connect

Some approximate solutions of the Low equations for pi-nucleon scattering, pi-nuclear scattering and the pp ..-->.. d..pi../sup +/ reaction are discussed. Results differ from those of other treatments by the inclusion of propagator modifications which act as cutoffs for terms involving pions of relatively small momenta. Because of these propagator modifications the use of a pi-nucleon T-matrix of long range is perfectly consistent with the idea that the fundamental pi-nucleon form factor is of very short range. The origin of these propagator modifications is shown to be a proper evaluation of the energy dependence of the off-shell pi-nucleon scattering amplitude. As a consequence of the theory, good agreement with pp ..-->.. d..pi../sup +/ data is obtained without the inclusion of large effects from rho-meson exchange terms. 22 references.

Miller, G.A.

1979-01-01T23:59:59.000Z

246

Holographic thermal field theory on curved spacetimes  

E-Print Network (OSTI)

The AdS/CFT correspondence relates certain strongly coupled CFTs with large effective central charge $c_\\text{eff}$ to semi-classical gravitational theories with AdS asymptotics. We describe recent progress in understanding gravity duals for CFTs on non-trivial spacetimes at finite temperature, both in and out of equilibrium. Such gravity methods provide powerful new tools to access the physics of these strongly coupled theories, which often differs qualitatively from that found at weak coupling. Our discussion begins with basic aspects of AdS/CFT and progresses through thermal CFTs on the Einstein Static Universe and on periodically identified Minkowski spacetime. In the latter context we focus on states describing so-called plasma balls, which become stable at large $c_\\text{eff}$. We then proceed to out-of-equilibrium situations associated with dynamical bulk black holes. In particular, the non-compact nature of these bulk black holes allows stationary solutions with non-Killing horizons that describe time-independent flows of CFT plasma. As final a topic we consider CFTs on black hole spacetimes. This discussion provides insight into how the CFT transports heat between general heat sources and sinks of finite size. In certain phases the coupling to small sources can be strongly suppressed, resulting in negligible heat transport despite the presence of a deconfined plasma with sizeable thermal conductivity. We also present a new result, explaining how this so-called droplet behaviour is related to confinement via a change of conformal frame.

Donald Marolf; Mukund Rangamani; Toby Wiseman

2013-12-02T23:59:59.000Z

247

Green functions and dimensional reduction of quantum fields on product manifolds  

E-Print Network (OSTI)

We discuss Euclidean Green functions on product manifolds P=NxM. We show that if M is compact then the Euclidean field on P can be approximated by its zero mode which is a Euclidean field on N. We estimate the remainder of this approximation. We show that for large distances on N the remainder is small. If P=R^{D-1}xS^{beta}, where S^{beta} is a circle of radius beta, then the result reduces to the well-known approximation of the D dimensional finite temperature quantum field theory to D-1 dimensional one in the high temperature limit. Analytic continuation of Euclidean fields is discussed briefly.

Haba, Z

2007-01-01T23:59:59.000Z

248

Compact shell solitons in K field theories  

Science Conference Proceedings (OSTI)

Some models providing shell-shaped static solutions with compact support (compactons) in 3+1 and 4+1 dimensions are introduced, and the corresponding exact solutions are calculated analytically. These solutions turn out to be topological solitons and may be classified as maps S{sup 3}{yields}S{sup 3} and suspended Hopf maps, respectively. The Lagrangian of these models is given by a scalar field with a nonstandard kinetic term (K field) coupled to a pure Skyrme term restricted to S{sup 2}, rised to the appropriate power to avoid the Derrick scaling argument. Further, the existence of infinitely many exact shell solitons is explained using the generalized integrability approach. Finally, similar models allowing for nontopological compactons of the ball type in 3+1 dimensions are briefly discussed.

Adam, C.; Klimas, P.; Sanchez-Guillen, J. [Departamento de Fisica de Particulas, Universidad de Santiago and Instituto Galego de Fisica de Altas Enerxias (IGFAE), E-15782 Santiago de Compostela (Spain); Wereszczynski, A. [Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen O, Denmark and Institute of Physics, Jagiellonian University, Reymonta 4, Krakow, 30-059 (Poland)

2009-10-15T23:59:59.000Z

249

Theory of quantum metal to superconductor transitions in highly conducting systems  

SciTech Connect

We derive the theory of the quantum (zero temperature) superconductor to metal transition in disordered materials when the resistance of the normal metal near criticality is small compared to the quantum of resistivity. This can occur most readily in situations in which 'Anderson's theorem' does not apply. We explicitly study the transition in superconductor-metal composites, in an swave superconducting film in the presence of a magnetic field, and in a low temperature disordered d-wave superconductor. Near the point of the transition, the distribution of the superconducting order parameter is highly inhomogeneous. To describe this situation we employ a procedure which is similar to that introduced by Mott for description of the temperature dependence of the variable range hopping conduction. As the system approaches the point of the transition from the metal to the superconductor, the conductivity of the system diverges, and the Wiedemann-Franz law is violated. In the case of d-wave (or other exotic) superconductors we predict the existence of (at least) two sequential transitions as a function of increasing disorder: a d-wave to s-wave, and then an s-wave to metal transition.

Spivak, B.

2010-04-06T23:59:59.000Z

250

Theory of classical and quantum frustration in quantum many-body systems  

E-Print Network (OSTI)

We present a general scheme for the study of frustration in quantum systems. After introducing a universal measure of frustration for arbitrary quantum systems, we derive for it an exact inequality in terms of a class of entanglement monotones. We then state sufficient conditions for the ground states of quantum spin systems to saturate the inequality and confirm them with extensive numerical tests. These conditions provide a generalization to the quantum domain of the Toulouse criteria for classical frustration-free systems and establish a unified framework for studying the intertwining of geometric and quantum contributions to frustration.

Giampaolo, S M; Monras, A; Illuminati, F

2011-01-01T23:59:59.000Z

251

Quantum Computation Quantum Information  

E-Print Network (OSTI)

Quantum Computation and Quantum Information Samuel J. Lomonaco, Jr. and Howard E. Brandt editors Searches with a Quantum Robot .............................................. 12 pages Benioff, Paul Perturbation Theory and Numerical Modeling Quantum Logic Operations with a Large of Qubits

Lomonaco Jr., Samuel J.

252

Lax matrix solution of c=1 Conformal Field Theory  

E-Print Network (OSTI)

To a correlation function in a two-dimensional conformal field theory with the central charge c=1, we associate a matrix differential equation \\Psi'=L\\Psi, where the Lax matrix L is a matrix square root of the energy-momentum tensor. Then local conformal symmetry translates into isomonodromy of the differential equation. This provides a justification for the recently observed relation between four-point conformal blocks and solutions of the Painleve VI equation. This also provides a direct way to compute the three-point function of Runkel-Watts theory - the common c->1 limit of Minimal Models and Liouville theory.

Eynard, Bertrand

2013-01-01T23:59:59.000Z

253

Lax matrix solution of c=1 Conformal Field Theory  

E-Print Network (OSTI)

To a correlation function in a two-dimensional conformal field theory with the central charge c=1, we associate a matrix differential equation \\Psi'=L\\Psi, where the Lax matrix L is a matrix square root of the energy-momentum tensor. Then local conformal symmetry translates into isomonodromy of the differential equation. This provides a justification for the recently observed relation between four-point conformal blocks and solutions of the Painleve VI equation. This also provides a direct way to compute the three-point function of Runkel-Watts theory - the common c->1 limit of Minimal Models and Liouville theory.

Bertrand Eynard; Sylvain Ribault

2013-07-18T23:59:59.000Z

254

Two types of conservation laws. Connection of physical fields with material systems. Peculiarities of field theories  

E-Print Network (OSTI)

Historically it happen so that in branches of physics connected with field theory and of physics of material systems (continuous media) the concept of "conservation laws" has a different meaning. In field theory "conservation laws" are those that claim the existence of conservative physical quantities or objects. These are conservation laws for physical fields. In contrast to that in physics (and mechanics) of material systems the concept of "conservation laws" relates to conservation laws for energy, linear momentum, angular momentum, and mass that establish the balance between the change of physical quantities and external action. In the paper presented it is proved that there exist a connection between of conservation laws for physical fields and those for material systems. This points to the fact that physical fields are connected with material systems. Such results has an unique significance for field theories. This enables one to substantiate many basic principles of field theories, such as, for example, the unity of existing field theories and the causality. The specific feature of field theory equations, namely, their connection to the equations for material systems, is elicited. Such results have been obtained by using skew-symmetric differential forms, which reflect the properties of conservation laws.

L. I. Petrova

2008-12-02T23:59:59.000Z

255

Noise Kernel in Stochastic Gravity and Stress Energy Bi-Tensor of Quantum Fields in Curved Spacetimes  

E-Print Network (OSTI)

The noise kernel is the vacuum expectation value of the (operator-valued) stress-energy bi-tensor which describes the fluctuations of a quantum field in curved spacetimes. It plays the role in stochastic semiclassical gravity based on the Einstein-Langevin equation similar to the expectation value of the stress-energy tensor in semiclassical gravity based on the semiclassical Einstein equation. According to the stochastic gravity program, this two point function (and by extension the higher order correlations in a hierarchy) of the stress energy tensor possesses precious statistical mechanical information of quantum fields in curved spacetime and, by the self-consistency required of Einstein's equation, provides a probe into the coherence properties of the gravity sector (as measured by the higher order correlation functions of gravitons) and the quantum nature of spacetime. It reflects the low and medium energy (referring to Planck energy as high energy) behavior of any viable theory of quantum gravity, including string theory. It is also useful for calculating quantum fluctuations of fields in modern theories of structure formation and for backreaction problems in cosmological and black holes spacetimes. We discuss the properties of this bi-tensor with the method of point-separation, and derive a regularized expression of the noise-kernel for a scalar field in general curved spacetimes. One collorary of our finding is that for a massless conformal field the trace of the noise kernel identically vanishes. We outline how the general framework and results derived here can be used for the calculation of noise kernels for Robertson-Walker and Schwarzschild spacetimes.

Nicholas G Phillips; B. L. Hu

2000-10-05T23:59:59.000Z

256

Closed String Cohomology in Open String Field Theory  

E-Print Network (OSTI)

We show that closed string states in bosonic string field theory are encoded in the cyclic cohomology of cubic open string field theory (OSFT) which, in turn, classifies the deformations of OSFT. This cohomology is then shown to be independent of the open string background. Exact elements correspond to closed string gauge transformations, generic boundary deformations of Witten's 3-vertex and infinitesimal shifts of the open string background. Finally it is argued that the closed string cohomology and the cyclic cohomology of OSFT are isomorphic to each other.

Moeller, Nicolas

2010-01-01T23:59:59.000Z

257

Topological gauge theories from supersymmetric quantum mechanics on spaces of connections  

E-Print Network (OSTI)

We rederive the recently introduced $N=2$ topological gauge theories, representing the Euler characteristic of moduli spaces ${\\cal M}$ of connections, from supersymmetric quantum mechanics on the infinite dimensional spaces ${\\cal A}/{\\cal G}$ of gauge orbits. To that end we discuss variants of ordinary supersymmetric quantum mechanics which have meaningful extensions to infinite-dimensional target spaces and introduce supersymmetric quantum mechanics actions modelling the Riemannian geometry of submersions and embeddings, relevant to the projections ${\\cal A}\\rightarrow {\\cal A}/{\\cal G}$ and inclusions ${\\cal M}\\subset{\\cal A}/{\\cal G}$ respectively. We explain the relation between Donaldson theory and the gauge theory of flat connections in $3d$ and illustrate the general construction by other $2d$ and $4d$ examples.

M Blau; G Thompson

1991-12-20T23:59:59.000Z

258

Perturbation Theory Based on Darboux Transformation on One-Dimensional Dirac Equation in Quantum Computation  

E-Print Network (OSTI)

We present the recent works \\cite{trisetyarso2011} on the application of Darboux transformation on one-dimensional Dirac equation related to the field of Quantum Information and Computation (QIC). The representation of physical system in one-dimensional equation and its transformation due to the Bagrov, Baldiotti, Gitman, and Shamshutdinova (BBGS)-Darboux transformation showing the possibility admitting the concept of relativity and the trade-off of concurrent condition of quantum and classical physics play into the area of QIC. The applications in cavity quantum electrodynamics and on the proposal of quantum transistor are presented.

Agung Trisetyarso

2010-05-11T23:59:59.000Z

259

Quantum Inference and . . . -- Development of a Theory for the Disjunction of Concepts  

E-Print Network (OSTI)

We elaborate a theory for the modeling of concepts using the mathematical structure of quantum mechanics. Items and concepts are represented by vectors in the complex Hilbert space of quantum mechanics and membership weights of items are modeled by quantum weights calculated following the quantum rules. We apply this theory to model the disjunction of concepts and show that the predictions of our theory for the membership weights of items with respect to the disjunction of concepts match with great accuracy the results of an experiment conducted by Hampton (1988b). It is the quantum effects of interference and superposition that are at the origin of the effects of overextension and underextension observed by Hampton as deviations from a classical use of the disjunction. We show that the complex numbers of the Hilbert space are essential to obtaining the experimental predictions, i.e. vector space models over real numbers do not provide predictions matching the experimental data. We put forward an explanation of the effects of overextension and underextension by interpreting the quantum model applied to the modeling of the disjunction of concepts.

Diederik Aerts

2007-01-01T23:59:59.000Z

260

Quantum Driven Dissipative Parametric Oscillator in a Blackbody Radiation Field  

E-Print Network (OSTI)

We consider the general open system problem of a charged quantum oscillator confined in a harmonic trap, whose frequency can be arbitrarily modulated in time, that interacts with both an incoherent quantized (blackbody) radiation field and with an arbitrary coherent laser field. We assume that the oscillator is initially in thermodynamic equilibrium with its environment, a non-factorized initial density matrix of the system and the environment, and that at $t=0$ the modulation of the frequency, the coupling to the incoherent and the coherent radiation are switched on. The subsequent dynamics, induced by the presence of the blackbody radiation and the laser field, is studied in the framework of the influence functional approach. This approach allows incorporating, in \\emph{analytic closed formulae}, the non-Markovian character of the oscillator-environment interaction at any temperature as well the non-Markovian character of the blackbody radiation and its zero-point fluctuations. Expressions for the time evolution of the covariance matrix elements of the quantum fluctuations and the reduced density-operator are obtained.

Leonardo A. Pachn; Paul Brumer

2012-07-12T23:59:59.000Z

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


261

Dynamics of nuclear polarization in InGaAs quantum dots in a transverse magnetic field  

SciTech Connect

The time-resolved Hanle effect is examined for negatively charged InGaAs/GaAs quantum dots. Experimental data are analyzed by using an original approach to separate behavior of the longitudinal and transverse components of nuclear polarization. This made it possible to determine the rise and decay times of each component of nuclear polarization and their dependence on transverse magnetic field strength. The rise and decay times of the longitudinal component of nuclear polarization (parallel to the applied field) were found to be almost equal (approximately 5 ms). An analysis of the transverse component of nuclear polarization shows that the corresponding rise and decay times differ widely and strongly depend on magnetic field strength, increasing from a few to tens of milliseconds with an applied field between 20 and 100 mT. Current phenomenological models fail to explain the observed behavior of nuclear polarization. To find an explanation, an adequate theory of spin dynamics should be developed for the nuclear spin system of a quantum dot under conditions of strong quadrupole splitting.

Verbin, S. Yu., E-mail: syuv54@mail.ru; Gerlovin, I. Ya.; Ignatiev, I. V., E-mail: ivan_ignatiev@mail.ru; Kuznetsova, M. S.; Cherbunin, R. V. [St. Petersburg State University, Spin Optics Laboratory (Russian Federation); Flisinski, K.; Yakovlev, D. R.; Bayer, M. [Technische Universitaet Dortmund (Germany)

2012-04-15T23:59:59.000Z

262

Evaluating transport coefficients in real time thermal field theory  

E-Print Network (OSTI)

Transport coefficients in a hadronic gas have been calculated earlier in the imaginary time formulation of thermal field theory. The steps involved are to relate the defining retarded correlation function to the corresponding time-ordered one and to evaluate the latter in the conventional perturbation expansion. Here we carry out both the steps in the real time formulation.

S. Mallik; Sourav Sarkar

2012-11-12T23:59:59.000Z

263

Open-Closed String Correspondence in Open String Field Theory  

E-Print Network (OSTI)

We address the problem of describing different closed string backgrounds in background independent open string field theory: A shift in the closed string background corresponds to a collective excitation of open strings. As an illustration we apply the formalism to the case where the closed string background is a group manifold.

Baumgartl, Marco

2008-01-01T23:59:59.000Z

264

Electroweak structure of light nuclei within chiral effective field theory  

E-Print Network (OSTI)

We review the results of the most recent calculations for the electromagnetic structure of light nuclei, the weak muon capture on deuteron and 3He and the weak proton-proton capture reaction at energies of astrophysical interest, performed within the chiral effective field theory framework.

L. E. Marcucci

2013-11-04T23:59:59.000Z

265

Information channel capacity in the field theory estimation  

E-Print Network (OSTI)

The construction of the information capacity for the vector position parameter in the Minkowskian space-time is presented. This lays the statistical foundations of the kinematical term of the Lagrangian of the physical action for many field theory models, derived by the extremal physical information method of Frieden and Soffer.

J. S?adkowski; J. Syska

2012-12-26T23:59:59.000Z

266

Getting Beyond the State of the Art of Information Retrieval with Quantum Theory  

E-Print Network (OSTI)

According to the probability ranking principle, the document set with the highest values of probability of relevance optimizes information retrieval effectiveness given the probabilities are estimated as accurately as possible. The key point of this principle is the separation of the document set into two subsets with a given level of fallout and with the highest recall. If subsets of set measures are replaced by subspaces and space measures, we obtain an alternative theory stemming from Quantum Theory. That theory is named after vector probability because vectors represent event like sets do in classical probability. The paper shows that the separation into vector subspaces is more effective than the separation into subsets with the same available evidence. The result is proved mathematically and verified experimentally. In general, the paper suggests that quantum theory is not only a source of rhetoric inspiration, but is a sufficient condition to improve retrieval effectiveness in a principled way.

Melucci, Massimo

2011-01-01T23:59:59.000Z

267

Bosonic and Baryonic String Theory in Quantum Chromodynamics  

Science Conference Proceedings (OSTI)

Bosonic string formation in gauge theories is reviewed with particular attention to the confining flux in lattice QCD and its effective string theory description. Recent results on the Casimir energy of the ground state and the string excitation spectrum are analyzed in the Dirichlet string limit of large separation between static sources. The closed string-soliton (torelon) with electric flux winding around a compact dimension is discussed and a new bound state tower spectrum at baryon string junctions is presented.

Kuti, Julius [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)

2007-02-27T23:59:59.000Z

268

An exact RG formulation of quantum gauge theory  

E-Print Network (OSTI)

A gauge invariant Wilsonian effective action is constructed for pure SU(N) Yang-Mills theory by formulating the corresponding flow equation. Manifestly gauge invariant calculations can be performed i.e. without gauge fixing or ghosts. Regularisation is implemented in a novel way which realises a spontaneously broken SU(N|N) supergauge theory. As an example we sketch the computation of the one-loop beta function, performed for the first time without any gauge fixing.

Tim R. Morris

2001-02-19T23:59:59.000Z

269

Experimentally realizable control fields in quantum Lyapunov control  

E-Print Network (OSTI)

As a hybrid of techniques from open-loop and feedback control, Lyapunov control has the advantage that it is free from the measurement-induced decoherence but it includes the system's instantaneous message in the control loop. Often, the Lyapunov control is confronted with time delay in the control fields and difficulty in practical implementations of the control. In this paper, we study the effect of time-delay on the Lyapunov control, and explore the possibility of replacing the control field with a pulse train or a bang-bang signal. The efficiency of the Lyapunov control is also presented through examining the convergence time of the controlled system. These results suggest that the Lyapunov control is robust gainst time delay, easy to realize and effective for high-dimensional quantum systems.

X. X. Yi; S. L. Wu; Chunfeng Wu; X. L. Feng; C. H. Oh

2011-02-24T23:59:59.000Z

270

Experimentally realizable control fields in quantum Lyapunov control  

E-Print Network (OSTI)

As a hybrid of techniques from open-loop and feedback control, Lyapunov control has the advantage that it is free from the measurement-induced decoherence but it includes the system's instantaneous message in the control loop. Often, the Lyapunov control is confronted with time delay in the control fields and difficulty in practical implementations of the control. In this paper, we study the effect of time-delay on the Lyapunov control, and explore the possibility of replacing the control field with a pulse train or a bang-bang signal. The efficiency of the Lyapunov control is also presented through examining the convergence time of the controlled system. These results suggest that the Lyapunov control is robust gainst time delay, easy to realize and effective for high-dimensional quantum systems.

Yi, X X; Wu, Chunfeng; Feng, X L; Oh, C H

2011-01-01T23:59:59.000Z

271

Quantum groups  

Science Conference Proceedings (OSTI)

The theory of Quantum groups, although rather young, since the expression Quantum ... introduction of a suitable form of the quantum group, the algebra A...

272

Quantum theory of stimulated Cerenkov radiation of transverse electromagnetic waves by a low-density electron beam in a medium  

Science Conference Proceedings (OSTI)

The quantum theory of stimulated Cerenkov radiation of transverse electromagnetic waves by an electron beam in an anisotropic medium is presented. Relativistic quantum nonlinear equations of the Cerenkov beam instability are obtained. In the linear approximation, the quantum dispersion equation is derived and the instability growth increments are determined. The nonlinear problem of the saturation of the quantum Cerenkov beam instability is solved. (cerenkov radiation)

Kuzelev, Mikhail V [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-01-31T23:59:59.000Z

273

Effective Field Theory for Massive Gravitons and Gravity in Theory Space  

E-Print Network (OSTI)

We introduce a technique for restoring general coordinate invariance into theories where it is explicitly broken. This is the analog for gravity of the Callan-Coleman-Wess-Zumino formalism for gauge theories. We use this to elucidate the properties of interacting massless and massive gravitons. For a single graviton with a Planck scale Mpl and a mass mg, we find that there is a sensible effective field theory which is valid up to a high-energy cutoff Lambda parametrically above mg. Our methods allow for a transparent understanding of the many peculiarities associated with massive gravitons, among them the need for the Fierz-Pauli form of the Lagrangian, the presence or absence of the van Dam-Veltman-Zakharov discontinuity in general backgrounds, and the onset of non-linear effects and the breakdown of the effective theory at large distances from heavy sources. The natural sizes of all non-linear corrections beyond the Fierz-Pauli term are easily determined. The cutoff scales as Lambda ~ (mg^4 Mpl)^(1/5) for the Fierz-Pauli theory, but can be raised to Lambda ~ (mg^2 Mpl)^(1/3) in certain non-linear extensions. Having established that these models make sense as effective theories, there are a number of new avenues for exploration, including model building with gravity in theory space and constructing gravitational dimensions.

Nima Arkani-Hamed; Howard Georgi; Matthew D. Schwartz

2002-10-21T23:59:59.000Z

274

Lectures on String Theory  

E-Print Network (OSTI)

This is a one semester course on bosonic string theory aimed at beginning graduate students. The lectures assume a working knowledge of quantum field theory and general relativity. Contents: 1. The Classical String 2. The Quantum String 3. Open Strings and D-Branes 4. Introducing Conformal Field Theory 5. The Polyakov Path Integral and Ghosts 6. String Interactions 7. The Low-Energy Effective Action 8. Compactification and T-Duality

Tong, David

2009-01-01T23:59:59.000Z

275

New mechanism for nonlocality from string theory: UV-IR quantum entanglement and its imprints on the CMB  

Science Conference Proceedings (OSTI)

Puff field theories (PFT) arise as the decoupling limits of D3 branes in a Melvin universe and exhibit spatially nonlocal dynamics. Unlike other realizations of nonlocality in string theory, PFTs have full SO(3) rotational symmetry. In this work, we analyze the strongly coupled regime of a PFT through gravitational holography. We find a novel mechanism at the heart of the phenomenon of nonlocality: a quantum entanglement of UV and IR dynamics. In the holographic bulk, this translates to an apparent horizon splitting the space into two regions--with the UV completion of the PFT sitting at the horizon. We unravel this intricate UV-IR setting and devise a prescription for computing correlators that extends the original dictionary of holographic renormalization group. We then implement a cosmological scenario where PFT correlators set the initial conditions for primordial fluctuations. We compute the associated power spectrum of the cosmic microwave background and find that the scenario allows for a distinct stringy signature.

Minton, Gregory; Sahakian, Vatche [Harvey Mudd College, Physics Department, 241 Platt Boulevard, Claremont, California 91711 (United States)

2008-01-15T23:59:59.000Z

276

Local molecular field theory for the treatment of electrostatics  

E-Print Network (OSTI)

We examine in detail the theoretical underpinnings of previous successful applications of local molecular field (LMF) theory to charged systems. LMF theory generally accounts for the averaged effects of long-ranged components of the intermolecular interactions by using an effective or restructured external field. The derivation starts from the exact Yvon-Born-Green hierarchy and shows that the approximation can be very accurate when the interactions averaged over are slowly varying at characteristic nearest-neighbor distances. Application of LMF theory to Coulomb interactions alone allows for great simplifications of the governing equations. LMF theory then reduces to a single equation for a restructured electrostatic potential that satisfies Poisson's equation defined with a smoothed charge density. Because of this charge smoothing by a Gaussian of width sigma, this equation may be solved more simply than the detailed simulation geometry might suggest. Proper choice of the smoothing length sigma plays a major role in ensuring the accuracy of this approximation. We examine the results of a basic confinement of water between corrugated wall and justify the simple LMF equation used in a previous publication. We further generalize these results to confinements that include fixed charges in order to demonstrate the broader impact of charge smoothing by sigma. The slowly-varying part of the restructured electrostatic potential will be more symmetric than the local details of confinements.

Jocelyn M. Rodgers; John D. Weeks

2008-09-17T23:59:59.000Z

277

Interactive Visualization Package for 4D Lattice Field Theories  

E-Print Network (OSTI)

Recent interest in exploring local vacuum structure of QCD through the properties of the eigenmodes of the lattice Dirac operators rises again the challenge to visualize four-dimensional objects and structures which appear in lattice field theories. In spite of complex and powerful commercial visualization software packages on the market, there are reasons to develop Interactive Visualization Package (IVP). We believe that an apprehension of the complex structures is possible only through the interactive approach, with the user being able to manipulate data representations and slices through the lattice in real-time. Further insight should also be gained by an interactive parallel examination of different physical quantities, e.g. eigenmode density with topological charge or action densities. Finally, thanks to constantly falling hardware prices, IVP makes it possible to use almost any Linux PC as a visualization tool for research in lattice field theory.

Ivan Hip

2007-10-03T23:59:59.000Z

278

Quantum field theory in static external potentials and Hadamard states  

E-Print Network (OSTI)

We prove that the ground state for the Dirac equation on Minkowski space in static, smooth external potentials satisfies the Hadamard condition. We show that it follows from a condition on the support of the Fourier transform of the corresponding positive frequency solution. Using a Krein space formalism, we establish an analogous result in the Klein-Gordon case for a wide class of smooth potentials. Finally, we investigate overcritical potentials, i.e. which admit no ground states. It turns out, that numerous Hadamard states can be constructed by mimicking the construction of ground states, but this leads to a naturally distinguished one only under more restrictive assumptions on the potentials.

Micha? Wrochna

2011-08-15T23:59:59.000Z

279

Field Theory of Gravity Based on a Bose-Einstein Condensate Effect  

E-Print Network (OSTI)

An alternative quantum field theory for gravity is proposed for low energies based on an attractive effect between contaminants in a Bose-Einstein Condensate rather than on particle exchange. In the contaminant in condensate effect, contaminants cause a potential in an otherwise uniform condensate, forcing the condensate between two contaminants to a higher energy state. The energy of the system decreases as the contaminants come closer together, causing an attractive force between contaminants. It is proposed that mass-energy may have a similar effect on Einsteins space-time field, and gravity is quantized by the same method by which the contaminant in condensate effect is quantized. The resulting theory is finite and, if a physical condensate is assumed to underly the system, predictive. However, the proposed theory has several flaws at high energies and is thus limited to low energies. Falsifiable predictions are given for the case that the Higgs condensate is assumed to be the condensate underlying gravity. 1 1 Proposed Theory on a Scalar Field Within Bose-Einstein Condensates [1], the authors predict in a separate paper [2] the existence of a new effect which causes an attractive force between two contaminants, the contaminant in condensate (CIC) effect. It is proposed that contaminants act as a potential within the condensate. This causes the condensate in between two contaminates to jump to a higher energy state than if no contaminants existed. By assuming that the condensate behaves as a massive scalar field governed by: 1 c2 ?2?(t, x)

Alexander Oshmyansky

2008-01-01T23:59:59.000Z

280

Non-shell unstable particles in thermal field theory  

SciTech Connect

Using (nonrigorous) operator-algebraic and group-theoretic techniques the particle structure of interacting real-time thermal field theory is investigated. A description in terms of elementary unstable entities without a dispersion relation is arrived at. The asymptotic fields are found to be two-parameter generalized free fields. Contact with the Licht-field description of on-shell unstable particles is thereby achieved. Poincare-symmetry breaking and the rearrangement of spin to helicity at finite temperature are fully discussed and incorporated. A unique thermal Gell-Mann/Low formula is obtained. Feynman rules and renormalization conditions pertaining to non-shell thermal particles are given. Dissipation thereby naturally emerges. All relevant esoteric mathematics is explained. copyright 1988 Academic Press, Inc.

Landsman, N.P.

1988-08-15T23:59:59.000Z

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281

Polymer Field-Theory Simulations on Graphics Processing Units  

E-Print Network (OSTI)

We report the first CUDA graphics-processing-unit (GPU) implementation of the polymer field-theoretic simulation framework for determining fully fluctuating expectation values of equilibrium properties for periodic and select aperiodic polymer systems. Our implementation is suitable both for self-consistent field theory (mean-field) solutions of the field equations, and for fully fluctuating simulations using the complex Langevin approach. Running on NVIDIA Tesla T20 series GPUs, we find double-precision speedups of up to 30x compared to single-core serial calculations on a recent reference CPU, while single-precision calculations proceed up to 60x faster than those on the single CPU core. Due to intensive communications overhead, an MPI implementation running on 64 CPU cores remains two times slower than a single GPU.

Kris T. Delaney; Glenn H. Fredrickson

2012-04-24T23:59:59.000Z

282

Quantum Fluctuations in Holographic Theories with Hyperscaling Violation  

E-Print Network (OSTI)

In this short note we use holographic methods to study the response of quantum critical points with hyperscaling violation to a disturbance caused by a massive charged particle. We give analytical expressions for the two-point functions of the fluctuations of the massive probe as a function of arbitrary (allowed) values of the hyperscaling violation exponent {\\theta} and the dynamical exponent z. We point out the existence of markedly different behaviors of the two-point functions in the parameter space of {\\theta} and z at late times. In particular, as expected, the late-time dynamics of the probe becomes independent of its inertial mass in the range z+2{\\theta}/d>2.

Edalati, Mohammad; Garcia, Walter Tangarife

2012-01-01T23:59:59.000Z

283

High temperature, magnetic field assisted (sub)THz quantum cascade laser  

E-Print Network (OSTI)

We demonstrate magnetic field assisted, (sub)THz quantum cascade laser operating above 200 K. This is achieved through the application of strong magnetic fields which provide an additional lateral confinement in order to ...

Wade, Aaron

284

Circular dichroism: A general theory based on quantum electrodynamics  

Science Conference Proceedings (OSTI)

A theory of circular dichroism is developed through a direct calculation of the absorption rates for circularly polarized light on molecules. From this a differential rate as between left and right circularly polarized light is calculated. This is immediately related to the experimental data on circular dichroism. When the calculations are restricted to the dipole approximation we reproduce the rotatory strength in the form of a differential Einstein B coefficient. Higher moments are considered in detail and their effects analyzed for both the locked?in situation and the case of randomly oriented molecular absorbers. A general expression is obtained for the differential absorption rate.

E. A. Power; T. Thirunamachandran

1974-01-01T23:59:59.000Z

285

The Spacetime of Double Field Theory: Review, Remarks, and Outlook  

E-Print Network (OSTI)

We review double field theory (DFT) with emphasis on the doubled spacetime and its generalized coordinate transformations, which unify diffeomorphisms and b-field gauge transformations. We illustrate how the composition of generalized coordinate transformations fails to associate. Moreover, in dimensional reduction, the O(d,d) T-duality transformations of fields can be obtained as generalized diffeomorphisms. Restricted to a half-dimensional subspace, DFT includes `generalized geometry', but is more general in that local patches of the doubled space may be glued together with generalized coordinate transformations. Indeed, we show that for certain T-fold backgrounds with non-geometric fluxes, there are generalized coordinate transformations that induce, as gauge symmetries of DFT, the requisite O(d,d;Z) monodromy transformations. Finally we review recent results on the \\alpha' extension of DFT which, reduced to the half-dimensional subspace, yields intriguing modifications of the basic structures of generalized geometry.

Olaf Hohm; Dieter Lust; Barton Zwiebach

2013-09-11T23:59:59.000Z

286

Frozen-orbital and downfolding calculations with auxiliary-field quantum Monte Carlo  

E-Print Network (OSTI)

We describe the implementation of the frozen-orbital and downfolding approximations in the auxiliary-field quantum Monte Carlo (AFQMC) method. These approaches can provide significant computational savings compared to fully correlating all the electrons. While the many-body wave function is never explicit in AFQMC, its random walkers are Slater determinants, whose orbitals may be expressed in terms of any one-particle orbital basis. It is therefore straightforward to partition the full N-particle Hilbert space into active and inactive parts to implement the frozen-orbital method. In the frozen-core approximation, for example, the core electrons can be eliminated in the correlated part of the calculations, greatly increasing the computational efficiency, especially for heavy atoms. Scalar relativistic effects are easily included using the Douglas-Kroll-Hess theory. Using this method, we obtain a way to effectively eliminate the error due to single-projector, norm-conserving pseudopotentials in AFQMC. We also i...

Purwanto, Wirawan; Krakauer, Henry

2013-01-01T23:59:59.000Z

287

Quantum theory of rotational isomerism and Hill equation  

SciTech Connect

The process of rotational isomerism of linear triatomic molecules is described by the potential with two different-depth minima and one barrier between them. The corresponding quantum-mechanical equation is represented in the form that is a special case of the Hill equation. It is shown that the Hill-Schroedinger equation has a Klein's quadratic group symmetry which, in its turn, contains three invariant subgroups. The presence of these subgroups makes it possible to create a picture of energy spectrum which depends on a parameter and has many merging and branch points. The parameter-dependent energy spectrum of the Hill-Schroedinger equation, like Mathieu-characteristics, contains branch points from the left and from the right of the demarcation line. However, compared to the Mathieu-characteristics, in the Hill-Schroedinger equation spectrum the 'right' points are moved away even further for some distance that is the bigger, the bigger is the less deep well. The asymptotic wave functions of the Hill-Schroedinger equation for the energy values near the potential minimum contain two isolated sharp peaks indicating a possibility of the presence of two stable isomers. At high energy values near the potential maximum, the height of two peaks decreases, and between them there appear chaotic oscillations. This form of the wave functions corresponds to the process of isomerization.

Ugulava, A.; Toklikishvili, Z.; Chkhaidze, S.; Abramishvili, R. [I. Javakhishvili Tbilisi State University, 3, I. Chavchavadze Avenue, 0179 Tbilisi (Georgia); Chotorlishvili, L. [Institut fuer Physik, Martin-Luther Universitat Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120 Halle (Germany)

2012-06-15T23:59:59.000Z

288

Effective field theory for two-species bosons in an optical lattice: Multiple order, the Nambu-Goldstone bosons, the Higgs mode and vortex lattice  

E-Print Network (OSTI)

In the previous papers, we studied the bosonic t-J mode and derived an effective field theory, which is a kind of quantum XY model. The bosonic t-J model is expected to be realized by experiments of two-component cold atoms in an optical lattice. In this paper, we consider a similar XY model that describes phase diagram of the t-J model with a mass difference. Phase diagram and critical behavior of the quantum XY model are clarified by means of the Monte-Carlo simulations. Effective field theory that describes the phase structure and low-energy excitations of the quantum XY model is derived. Nambu-Goldstone bosons and the Higgs mode are studied by using the effective field theory and interesting findings are obtained for the system with multiple order, i.e., Bose-Einstein condensations and pseudo-spin symmetry. We also investigate physical properties of the quantum XY model in an effective magnetic field that is realized by rotating the optical lattice, etc. We show that low-energy states of the system strongly depend on the strength of the "magnetic field". For some specific strength of the magnetic field, vortex lattice forms and the correlation function of the bosons exhibits solid like behavior, which is a kind of Bose-Einstein condensation.

Y. Kuno; K. Suzuki; I. Ichinose

2013-06-10T23:59:59.000Z

289

Nuclear Lattice Simulations with Chiral Effective Field Theory  

E-Print Network (OSTI)

We study nuclear and neutron matter by combining chiral effective field theory with non-perturbative lattice methods. In our approach nucleons and pions are treated as point particles on a lattice. This allows us to probe larger volumes, lower temperatures, and greater nuclear densities than in lattice QCD. The low energy interactions of these particles are governed by chiral effective theory and operator coefficients are determined by fitting to zero temperature few-body scattering data. Any dependence on the lattice spacing can be understood from the renormalization group and absorbed by renormalizing operator coefficients. In this way we have a realistic simulation of many-body nuclear phenomena with no free parameters, a systematic expansion, and a clear theoretical connection to QCD. We present results for hot neutron matter at temperatures 20 to 40 MeV and densities below twice nuclear matter density.

Dean Lee; Bugra Borasoy; Thomas Schaefer

2004-02-23T23:59:59.000Z

290

Scaling Deviations for Neutrino Reactions in Aysmptotically Free Field Theories  

DOE R&D Accomplishments (OSTI)

Several aspects of deep inelastic neutrino scattering are discussed in the framework of asymptotically free field theories. We first consider the growth behavior of the total cross sections at large energies. Because of the deviations from strict scaling which are characteristic of such theories the growth need not be linear. However, upper and lower bounds are established which rather closely bracket a linear growth. We next consider in more detail the expected pattern of scaling deviation for the structure functions and, correspondingly, for the differential cross sections. The analysis here is based on certain speculative assumptions. The focus is on qualitative effects of scaling breakdown as they may show up in the X and y distributions. The last section of the paper deals with deviations from the Callan-Gross relation.

Wilczek, F. A.; Zee, A.; Treiman, S. B.

1974-11-01T23:59:59.000Z

291

Supersymmetric Yang Mills Fields and Black Holes ; In Ten Dimensional Unified Field Theory  

E-Print Network (OSTI)

The Ten dimensional Unified field theory has a 4 dimensional Riemannian spacetime and six dimensional Calabi Yau space structure. The supersymmetric Yang Mills fields and black holes are solutions in these theories. The formation of primordial black holes in early universe, the collapse to singularity of stellar black holes, the Hawking evaporation of microscopic black holes in LHC are topics of observational and theoretical interest. The observation of gamma ray bursts and creation of spectrum of particles and radiation of dark and normal matter occur due to primordial and microscopic black holes. The approach to singularity in black hole interior solutions, require the Bogoliubov transforms of SUSY YM fields in black hole geometries; both during formation and in evaporation. The Hawking effect of radiating black holes is applicable for all the fields. Invariants can be defined to give the conditions for these processes.

Ajay Patwardhan

2007-05-17T23:59:59.000Z

292

Spectral functions for composite fields and viscosity in hot scalar field theory  

E-Print Network (OSTI)

We derive a spectral representation for the two-point Green function for arbitrary composite field operators in Thermo Field Dynamics (TFD). A simple way for calculating the spectral density within TFD is pointed out and compared with known results from the imaginary time formalism. The method is applied to hot $\\phi^4$ theory. We give a compact derivation of the one-loop contribution to the shear viscosity and show that it is dominated by low-momentum plasmons.

Enke Wang; Xiaofei Zhang; Ulrich Heinz

1995-09-19T23:59:59.000Z

293

Non-Markovian stochastic Schrdinger equations: Generalization to real-valued noise using quantum measurement theory  

E-Print Network (OSTI)

Do stochastic Schr\\"odinger equations, also known as unravelings, have a physical interpretation? In the Markovian limit, where the system {\\em on average} obeys a master equation, the answer is yes. Markovian stochastic Schr\\"odinger equations generate quantum trajectories for the system state conditioned on continuously monitoring the bath. For a given master equation, there are many different unravelings, corresponding to different sorts of measurement on the bath. In this paper we address the non-Markovian case, and in particular the sort of stochastic \\sch equation introduced by Strunz, Di\\' osi, and Gisin [Phys. Rev. Lett. 82, 1801 (1999)]. Using a quantum measurement theory approach, we rederive their unraveling which involves complex-valued Gaussian noise. We also derive an unraveling involving real-valued Gaussian noise. We show that in the Markovian limit, these two unravelings correspond to heterodyne and homodyne detection respectively. Although we use quantum measurement theory to define these unravelings, we conclude that the stochastic evolution of the system state is not a true quantum trajectory, as the identity of the state through time is a fiction.

Jay Gambetta; H. M. Wiseman

2002-02-20T23:59:59.000Z

294

Tail terms in gravitational radiation reaction via effective field theory  

E-Print Network (OSTI)

Gravitational radiation reaction affects the dynamics of gravitationally bound binary systems. Here we focus on the leading "tail" term which modifies binary dynamics at fourth post-Newtonian order, as first computed by Blanchet and Damour. We re-produce this result using effective field theory techniques in the framework of the Lagrangian formalism suitably extended to include dissipation effects. We recover the known logarithmic tail term, consistently with the recent interpretation of the logarithmic tail term in the mass parameter as a renormalization group effect of the Bondi mass of the system.

S. Foffa; R. Sturani

2011-11-23T23:59:59.000Z

295

Quantum process and the foundation of relational theories of space-time  

E-Print Network (OSTI)

We present current theories about the structure of space and time, where the building blocks are some fundamental entities (yes-no experiment, quantum processes, spin net-work, preparticles) that do not presuppose the existence of space and time. The relations among these objects are the base for a pregeometry of discrete character, the continuous limit of which gives rise to the physical properties of the space and time.

M. Lorente

2003-12-30T23:59:59.000Z

296

Designing new apartment buildings for strings and conformal field theories. First steps  

E-Print Network (OSTI)

The concepts of apartments and buildings were suggested by Tits for description of the Weyl-Coxeter reflection groups. We use these and many additional facts from the theory of reflection and pseudo-reflection groups along with results from the algebraic and symplectic geometry of toric varieties in order to obtain the tachyon-free Veneziano-like multiparticle scattering amplitudes and the partition function generating these amplitudes.Although the obtained amplitudes reproduce the tachyon-free spectra of both open and closed boisonic string, the generating (partition) function is not that of the traditional bosonic string. It is argued that it is directly related to the N=2 sypersymmetric quantum mechanical model proposed by Witten in 1982 in connection with his development of the Morse theory.Such partition function can be independently obtained with help of the results by Solomon (published in 1963) on invariants of finite (pseudo) reflection groups. Although the formalism developed in this work is also applicable to conformal field theories (CFT), it leaves all CFT results unchanged

Arkady L. Kholodenko

2003-12-26T23:59:59.000Z

297

Nuclear Symmetry Energy in Relativistic Mean Field Theory  

E-Print Network (OSTI)

The Physical origin of the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. Based on the nuclear binding energies calculated with and without mean isovector potential for several isobaric chains we conform earlier Skyrme-Hartree-Fock result that the nuclear symmetry energy strength depends on the mean level spacing $\\epsilon (A)$ and an effective mean isovector potential strength $\\kappa (A)$. A detaied analysis of isospin dependence of the two components contributing to the nuclear symmetry energy reveals a quadratic dependence due to the mean-isoscalar potential, $\\sim\\epsilon T^2$, and, completely unexpectedly, the presence of a strong linear component $\\sim\\kappa T(T+1+\\epsilon/\\kappa)$ in the isovector potential. The latter generates a nuclear symmetry energy in RMF theory that is proportional to $E_{sym}\\sim T(T+1)$ at variance to the non-relativistic calculation. The origin of the linear term in RMF theory needs to be further explored.

Shufang Ban; Jie Meng; Wojciech Satula; Ramon A. Wyss

2005-09-12T23:59:59.000Z

298

Transient Quantum Coherent Response to a Partially Coherent Radiation Field  

E-Print Network (OSTI)

The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level $V$ system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly difference from traditional decoherence. These two excitation scenarios are also explored for a minimal "toy" model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.

Z. S. Sadeq; Paul Brumer

2013-12-10T23:59:59.000Z

299

More is the Same; Phase Transitions and Mean Field Theories  

E-Print Network (OSTI)

This paper looks at the early theory of phase transitions. It considers a group of related concepts derived from condensed matter and statistical physics. The key technical ideas here go under the names of "singularity", "order parameter", "mean field theory", and "variational method". In a less technical vein, the question here is how can matter, ordinary matter, support a diversity of forms. We see this diversity each time we observe ice in contact with liquid water or see water vapor, "steam", come up from a pot of heated water. Different phases can be qualitatively different in that walking on ice is well within human capacity, but walking on liquid water is proverbially forbidden to ordinary humans. These differences have been apparent to humankind for millennia, but only brought within the domain of scientific understanding since the 1880s. A phase transition is a change from one behavior to another. A first order phase transition involves a discontinuous jump in a some statistical variable of the system. The discontinuous property is called the order parameter. Each phase transitions has its own order parameter that range over a tremendous variety of physical properties. These properties include the density of a liquid gas transition, the magnetization in a ferromagnet, the size of a connected cluster in a percolation transition, and a condensate wave function in a superfluid or superconductor. A continuous transition occurs when that jump approaches zero. This note is about statistical mechanics and the development of mean field theory as a basis for a partial understanding of this phenomenon.

Leo P. Kadanoff

2009-06-03T23:59:59.000Z

300

Dynamic Self-Consistent Field Theory for Unentangled Homopolymer Fluids  

E-Print Network (OSTI)

We present a lattice formulation of a dynamic self-consistent field (DSCF) theory that is capable of resolving interfacial structure, dynamics and rheology in inhomogeneous, compressible melts and blends of unentangled homopolymer chains. The joint probability distribution of all the Kuhn segments in the fluid, interacting with adjacent segments and walls, is approximated by a product of one-body probabilities for free segments interacting solely with an external potential field that is determined self-consistently. The effect of flow on ideal chain conformations is modeled with FENE-P dumbbells, and related to stepping probabilities in a random walk. Free segment and stepping probabilities generate statistical weights for chain conformations in a self-consistent field, and determine local volume fractions of chain segments. Flux balance across unit lattice cells yields mean-field transport equations for the evolution of free segment probabilities and of momentum densities on the Kuhn length scale. Diffusive and viscous contributions to the fluxes arise from segmental hops modeled as a Markov process, with transition rates reflecting changes in segmental interaction, kinetic energy, and entropic contributions to the free energy under flow.

Maja Mihajlovic; Tak Shing Lo; Yitzhak Shnidman

2004-11-10T23:59:59.000Z

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


301

Thermodynamics and Universality for Mean Field Quantum Spin Glasses  

E-Print Network (OSTI)

We study aspects of the thermodynamics of quantum versions of spin glasses. By means of the Lie-Trotter formula for exponential sums of operators, we adapt methods used to analyze classical spin glass models to answer analogous questions about quantum models.

Nick Crawford

2006-10-13T23:59:59.000Z

302

Intrinsic atomic orbitals: An unbiased bridge between quantum theory and chemical concepts  

E-Print Network (OSTI)

Modern quantum chemistry can make quantitative predictions on an immense array of chemical systems. However, the interpretation of those predictions is often complicated by the complex wave function expansions used. Here we show that an exceptionally simple algebraic construction allows for defining atomic core and valence orbitals, polarized by the molecular environment, which can exactly represent self-consistent field wave functions. This construction provides an unbiased and direct connection between quantum chemistry and empirical chemical concepts, and can be used, for example, to calculate the nature of bonding in molecules, in chemical terms, from first principles.

Knizia, Gerald

2013-01-01T23:59:59.000Z

303

The effect of temperature and magnetic field on a quantum rod qubit  

Science Conference Proceedings (OSTI)

The Hamiltonian of a quantum rod (QR) with an ellipsoidal boundary is given after a coordinate transformation, which changes the ellipsoidal boundary into a spherical one. We obtain the eigenenergies and eigenfunctions of the ground and the first excited ... Keywords: Magnetic field, Quantum rod, Qubit, Temperature effect

Yong Sun; Zhao-Hua Ding; Jing-Lin Xiao

2013-02-01T23:59:59.000Z

304

Manipulation and storage of optical field and atomic ensemble quantum states  

E-Print Network (OSTI)

We study how to efficiently manipulate and store quantum information between optical fields and atomic ensembles. We show how various non-dissipative transfer schemes can be used to transfer and store quantum states such as squeezed vacuum states or entangled states into the long-lived ground state spins of atomic ensembles.

Aurelien Dantan; Alberto Bramati; Michel Pinard; Elisabeth Giacobino

2004-07-28T23:59:59.000Z

305

Global Solutions of Hartree-Fock Theory and their Consequences for Strongly Correlated Quantum Systems  

E-Print Network (OSTI)

We present a density matrix approach for computing global solutions of Hartree-Fock theory, based on semidefinite programming (SDP), that gives upper and lower bounds on the Hartree-Fock energy of quantum systems. Equality of the upper- and lower-bound energies guarantees that the computed solution is the globally optimal solution of Hartree-Fock theory. For strongly correlated systems the SDP approach requires us to reassess the accuracy of the Hartree-Fock energies and densities from standard software packages for electronic structure theory. Calculations of the H$_{4}$ dimer and N$_{2}$ molecule show that the energies from SDP Hartree-Fock are lower than those from standard Hartree-Fock methods by 100-200 kcal/mol in the dissociation region. The present findings have important consequences for the computation and interpretation of electron correlation, which is typically defined relative to the Hartree-Fock energy and density.

Veeraraghavan, Srikant

2013-01-01T23:59:59.000Z

306

Time-dependent restricted-active-space self-consistent field theory for laser-driven many-electron dynamics  

E-Print Network (OSTI)

We present the time-dependent restricted-active-space self-consistent field (TD-RASSCF) theory as a new framework for the time-dependent many-electron problem. The theory generalizes the multiconfigurational time-dependent Hartree-Fock (MCTDHF) theory by incorporating the restricted-active-space scheme well known in time-independent quantum chemistry. Optimization of the orbitals as well as the expansion coefficients at each time step makes it possible to construct the wave function accurately while using only a relatively small number of electronic configurations. In numerical calculations of high-order harmonic generation spectra of a one-dimensional model of atomic beryllium interacting with a strong laser pulse, the TD-RASSCF method is reasonably accurate while largely reducing the computational complexity. The TD-RASSCF method has the potential to treat large atoms and molecules beyond the capability of the MCTDHF method.

Miyagi, Haruhide

2013-01-01T23:59:59.000Z

307

Causal signal transmission by quantum fields. VI: Phase-space approach to quantum electrodynamics  

E-Print Network (OSTI)

Phase-space techniques are generalized to nonlinear quantum electrodynamics beyond the rotating wave approximation, resulting in an essentially classical picture of radiation dynamics.

L. I. Plimak; S. T. Stenholm

2011-04-19T23:59:59.000Z

308

More is the Same; Phase Transitions and Mean Field Theories  

E-Print Network (OSTI)

This paper Looks at the early theory of phase transitions. It considers a group of related concepts derived from condensed matter and statistical physics. The key technical ideas here go under the names of "singularity", "order parameter", "mean field theory", and "variational method". In a less technical vein, the question here is how can matter, ordinary matter, support a diversity of forms. We see this diversity each time we observe ice in contact with liquid water or see water vapor, "steam", come up from a pot of heated water. Different phases can be qualitatively different in that walking on ice is well within human capacity, but walking on liquid water is proverbially forbidden to ordinary humans. These differences have been apparent to humankind for millennia, but only brought within the domain of scientific understanding since the 1880s. A phase transition is a change from one behavior to another. A first order phase transition involves a discontinuous jump in a some statistical variable of the syste...

Kadanoff, Leo P

2009-01-01T23:59:59.000Z

309

I THE THEORY OF QUANTIZED FIELDS I11 J  

NLE Websites -- All DOE Office Websites (Extended Search)

" " THE THEORY OF QUANTIZED FIELDS I11 J d i a n Schwinger i Harvard University Cambridge, Mass. I . 1 i DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement,

310

U(1) X U(1) XI Z(2) Chern-Simons theory and Z(4) parafermion fractional quantum Hall states  

E-Print Network (OSTI)

We study U(1)U(1)?Z2 Chern-Simons theory with integral coupling constants (k,l) and its relation to certain non-Abelian fractional quantum Hall (FQH) states. For the U(1)U(1)?Z2 Chern-Simons theory, we show how to compute ...

Barkeshli, Maissam

311

PERTURBATION-THEORY RULES FOR COMPUTING THE SELF-ENERGY OPERATOR IN QUANTUM STATISTICAL MECHANICS  

E-Print Network (OSTI)

D. J. Thouless, The Quantum Mechanics of Many-Body Systems (1962). Ba~n, Quantum Statistical Mechanics (Benjamin, I. E.IN QUANTUM STATISTICAL MECHANICS Berkeley, California

Baym, Gordon

2008-01-01T23:59:59.000Z

312

Introduction to Loop Quantum Gravity  

E-Print Network (OSTI)

The questions I have been asked during the 5th International School on Field Theory and Gravitation, have compelled me to give an account of the premises that I consider important for a beginner's approach to Loop Quantum Gravity. After a description of some general arguments and an introduction to the canonical theory of gravity, I review the background independent approach to quantum gravity, giving only a brief survey of Loop Quantum Gravity.

Mercuri, Simone

2010-01-01T23:59:59.000Z

313

Introduction to Loop Quantum Gravity  

E-Print Network (OSTI)

The questions I have been asked during the 5th International School on Field Theory and Gravitation, have compelled me to give an account of the premises that I consider important for a beginner's approach to Loop Quantum Gravity. After a description of some general arguments and an introduction to the canonical theory of gravity, I review the background independent approach to quantum gravity, giving only a brief survey of Loop Quantum Gravity.

Simone Mercuri

2010-01-08T23:59:59.000Z

314

Dissipative Effects in the Effective Field Theory of Inflation  

SciTech Connect

We generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators, {Omicron}{sub {mu}{nu}}..., in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of 'friction' and noise terms, and assuming certain locality properties for the Green's functions of these composite operators, we show that there is a regime characterized by a large friction term {gamma} >> H in which the {zeta}-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function <{zeta}{zeta}{zeta}> for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies |f{sub NL}| {approx} {gamma}/c{sub s}{sup 2} H >> 1. As a paradigmatic example we work out a variation of the 'trapped inflation' scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models.

Lopez Nacir, Diana; /Buenos Aires, CONICET /Buenos Aires U.; Porto, Rafael A.; /Princeton, Inst. Advanced Study /ISCAP, New York /Columbia U.; Senatore, Leonardo; /Stanford U., ITP /SLAC /KIPAC, Menlo Park; Zaldarriaga, Matias; /Princeton, Inst. Advanced Study

2012-09-14T23:59:59.000Z

315

Electromagnetically induced vorticity control in a quantum fluid velocity field  

E-Print Network (OSTI)

A new method is reported by which it is possible to induce certain flux configurations of desired characteristics via electromagnetic means into the overall quantum probability current of a many-body system in the Madelung hydrodynamic picture. Some indicative applications are also considered with emphasis in HTC and gravitational wave research.

T. E. Raptis

2013-06-19T23:59:59.000Z

316

The influence of external fields on the energy of two interacting electrons in a quantum dot  

SciTech Connect

In this paper, the effects of both an external electric field and an external magnetic field on the energy of two interacting electrons in a two-dimensional parabolic quantum dot are investigated for various quantum states (n,|m|) in the framework of the asymptotic iteration method. It is seen that the energy eigenvalues increase monotonically with increasing electric and magnetic field strengths in the weak- and strong-field regimes. However, the behavior is slightly different in the two regimes. Whereas the energy values increase linearly in the low-electric-field regime, they increase much more than linearly in the strong-field regime. This paper demonstrates that it is possible to obtain the energy eigenvalues of two electrons in a two-dimensional parabolic quantum dot not only for cases with and without an electric field and with and without a magnetic field, but also for cases where magnetic and electric fields (either strong or weak) are present simultaneously. - Highlights: Black-Right-Pointing-Pointer The energy eigenvalues of two electrons in a 2D quantum dot in external electric and magnetic fields are discussed. Black-Right-Pointing-Pointer The effects of the fields on the energies are obtained for strong and weak fields. Black-Right-Pointing-Pointer The energies increase monotonically with increasing field. Black-Right-Pointing-Pointer The increase in the energies in weak fields has a different behavior from that in strong fields. Black-Right-Pointing-Pointer The method used here is very efficient for discovering the effects of external fields on different states.

Soylu, A., E-mail: asimsoylu@gmail.com

2012-12-15T23:59:59.000Z

317

Chameleonic dilaton, nonequivalent frames, and the cosmological constant problem in quantum string theory  

Science Conference Proceedings (OSTI)

The chameleonic behavior of the string theory dilaton is suggested. Some of the possible consequences of the chameleonic string dilaton are analyzed in detail. In particular, (1) we suggest a new stringy solution to the cosmological constant problem and (2) we point out the nonequivalence of different conformal frames at the quantum level. In order to obtain these results, we start taking into account the (strong coupling) string loop expansion in the string frame (S-frame), therefore the so-called form factors are present in the effective action. The correct dark energy scale is recovered in the Einstein frame (E-frame) without unnatural fine-tunings and this result is robust against all quantum corrections, granted that we assume a proper structure of the S-frame form factors in the strong coupling regime. At this stage, the possibility still exists that a certain amount of fine-tuning may be required to satisfy some phenomenological constraints. Moreover in the E-frame, in our proposal, all the interactions are switched off on cosmological length scales (i.e., the theory is IR-free), while higher derivative gravitational terms might be present locally (on short distances) and it remains to be seen whether these facts clash with phenomenology. A detailed phenomenological analysis is definitely necessary to clarify these points.

Zanzi, Andrea [Via Pioppa 261, 44123 Pontegradella, Ferrara (Italy)

2010-08-15T23:59:59.000Z

318

Simple Space-Time Symmetries: Generalizing Conformal Field Theory  

E-Print Network (OSTI)

We study simple space-time symmetry groups G which act on a space-time manifold M=G/H which admits a G-invariant global causal structure. We classify pairs (G,M) which share the following additional properties of conformal field theory: 1) The stability subgroup H of a point in M is the identity component of a parabolic subgroup of G, implying factorization H=MAN, where M generalizes Lorentz transformations, A dilatations, and N special conformal transformations. 2) special conformal transformations in N act trivially on tangent vectors to the space-time manifold M. The allowed simple Lie groups G are the universal coverings of SU(m,m), SO(2,D), Sp(l,R), SO*(4n) and E_7(-25) and H are particular maximal parabolic subgroups. They coincide with the groups of fractional linear transformations of Euklidean Jordan algebras whose use as generalizations of Minkowski space time was advocated by Gunaydin. All these groups G admit positive energy representations. It will also be shown that the classical conformal groups SO(2,D) are the only allowed groups which possess a time reflection automorphism; in all other cases space-time has an intrinsic chiral structure.

Gerhard Mack; Mathias de Riese

2004-10-28T23:59:59.000Z

319

Bayesian Methods for Parameter Estimation in Effective Field Theories  

E-Print Network (OSTI)

We demonstrate and explicate Bayesian methods for fitting the parameters that encode the impact of short-distance physics on observables in effective field theories (EFTs). We use Bayes' theorem together with the principle of maximum entropy to account for the prior information that these parameters should be natural, i.e.O(1) in appropriate units. Marginalization can then be employed to integrate the resulting probability density function (pdf) over the EFT parameters that are not of specific interest in the fit. We also explore marginalization over the order of the EFT calculation, M, and over the variable, R, that encodes the inherent ambiguity in the notion that these parameters are O(1). This results in a very general formula for the pdf of the EFT parameters of interest given a data set, D. We use this formula and the simpler "augmented chi-squared" in a toy problem for which we generate pseudo-data. These Bayesian methods, when used in combination with the "naturalness prior", facilitate reliable extractions of EFT parameters in cases where chi-squared methods are ambiguous at best. We also examine the problem of extracting the nucleon mass in the chiral limit, M_0, and the nucleon sigma term, from pseudo-data on the nucleon mass as a function of the pion mass. We find that Bayesian techniques can provide reliable information on M_0, even if some of the data points used for the extraction lie outside the region of applicability of the EFT.

Matthias R. Schindler; Daniel R. Phillips

2008-08-27T23:59:59.000Z

320

Double wells, scalar fields and quantum phase transitions in ions traps  

E-Print Network (OSTI)

Since Hund's work on the ammonia molecule, the double well potential has formed a key paradigm in physics. Its importance is further underlined by the central role it plays in the Landau theory of phase transitions. Recently, the study of entanglement properties of many-body systems has added a new angle to the study of quantum phase transitions of discrete and continuous degrees of freedom, i.e., spin and harmonic chains. Here we show that control of the radial degree of freedom of trapped ion chains allows for the simulation of linear and non-linear Klein-Gordon fields on a lattice, in which the parameters of the lattice, the non-linearity and mass can be controlled at will. The system may be driven through a phase transition creating a double well potential between different configurations of the ion crystal. The dynamics of the system are controllable, local properties are measurable and tunnelling in the double well potential would be observable.

A. Retzker; R. Thompson; D. Segal; M. B. Plenio

2008-01-04T23:59:59.000Z

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


321

Mass gap in quantum energy-mass spectrum of relativistic Yang-Mills fields  

E-Print Network (OSTI)

A relativistic quantum Yang-Mills theory with a simple compact gauge Lie group on the four-dimensional Minkowski spacetime is set up in a framework of infinite-dimensional pseudodifferential operators in a nuclear Kree-Gelfand triple. The linear quantum Yang-Mills energy-mass operator is defined as the anti-normal quantization of the non-linear Yang-Mills energy-mass functional of consrained Cauchy data supported by an euclidean ball of a radius R. It is shown that expectation functional of the Yang-Mills energy-mass operator majorises the expectation functional of a scaled occupation number operator so that, by variational spectral principles, the quantum Yang-Mills spectral mass gap is positive. The mass gap is proportional to 1/R. The running coupling constant is proportional to the square root of R, leading to an asymptotic freedom for quantum Yang-Mills theory at short distances. This mathematically rigorous theory is non-perturbative and provides a solution for the 7th Clay Institute Millennium problem.

Alexander Dynin

2013-08-29T23:59:59.000Z

322

Phase-only shaped laser pulses in optimal control theory: Application to indirect photofragmentation dynamics in the weak-field limit  

SciTech Connect

We implement phase-only shaped laser pulses within quantum optimal control theory for laser-molecule interaction. This approach is applied to the indirect photofragmentation dynamics of NaI in the weak-field limit. It is shown that optimized phase-modulated pulses with a fixed frequency distribution can substantially modify transient dissociation probabilities as well as the momentum distribution associated with the relative motion of Na and I.

Shu, Chuan-Cun; Henriksen, Niels E. [Department of Chemistry, Building 207, Technical University of Denmark, DK-2800, Kongens Lyngby (Denmark)

2012-01-28T23:59:59.000Z

323

Thermodynamics and Finite size scaling in Scalar Field Theory  

E-Print Network (OSTI)

In this work we consider the 1-component real scalar $\\phi^4$ theory in 4 space-time dimensions on the lattice and investigate the finite size scaling of thermodynamic quantities to study whether the thermodynamic limit is attained. The results are obtained for the symmetric phase of the theory.

Debasish Banerjee; Saumen Datta; Sourendu Gupta

2008-12-05T23:59:59.000Z

324

Dispersion theory of nucleon polarizabilities and outlook on chiral effective field theory  

E-Print Network (OSTI)

The polarizabilities of the nucleon are precisely studied and well understood due to recent experimental and theoretical work based on nonsubtracted dispersion relations. The {\\it recommended} experimental values are $\\alpha_p=12.0\\pm 0.6$, $(12.0)$, $\\beta_p=1.9\\mp 0.6$, $(1.9)$, $\\alpha_n=12.5\\pm 1.7$, $(12.7\\pm 0.9)$, $\\beta_n=2.7\\mp 1.8$, $(2.5\\mp 0.9)$ in units of $10^{-4}$fm$^3$ and $\\gamma^{(p)}_\\pi=-36.4\\pm 1.5$, $(-36.6)$, $\\gamma^{(n)}_\\pi=+58.6\\pm 4.0$, $(58.3)$, $(\\gamma^{(p)}_0=-0.58\\pm 0.20)$, $\\gamma^{(n)}_0=0.38\\pm 0.22)$ in units of $10^{-4}$fm$^4$ [1]. The numbers given in parentheses are predicted values. Recently attempts to reanalyse low-energy Compton scattering data by making use of different versions of chiral effective field theory ($\\chi$EFT) have led to sizable discrepancies between each other and with the {\\it recommended} experimental data. An investigation is presented showing that these newly analyzed data should not be included in the {\\it recommendation}.

Martin Schumacher

2013-07-08T23:59:59.000Z

325

Electronic excitations and transport in aperiodic sequences of quantum dots in external electric and magnetic fields  

Science Conference Proceedings (OSTI)

The energy spectra and transport of electronic excitations in one-dimensional aperiodic sequences of quantum dots of Thue-Morse and double-periodic type are studied. The influence of external magnetic and electric fields on the energy spectra and transport is considered. For aperiodic sequences of quantum dots, in contrast to aperiodic sequences of atoms, the influence of relatively small magnetic and electric fields is essential, but localization occurs at finite values of the perturbations. The transmission coefficient is determined using the quasiclassical approximation with the Coulomb blockade taken into account. The resonance tunneling is studied.

Korotaev, P. Yu., E-mail: pvl.korotaev@gmail.com; Kaputkina, N. E. [National University of Science and Technology 'MISIS' (Russian Federation); Lozovik, Yu. E. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation); Vekilov, Yu. Kh. [National University of Science and Technology 'MISIS' (Russian Federation)

2011-10-15T23:59:59.000Z

326

DISCIPLE-1: interactive apprentice system in weak theory fields  

Science Conference Proceedings (OSTI)

The paper presents an interactive approach to learning apprentice systems for weak theory domains. The approach consists of a combination of teaming by analogy and learning by generalizing instances. One main point of this approach is that it uses the ...

Yves Kodratoff; Gheorghe Tecuci

1987-08-01T23:59:59.000Z

327

Synchrotron radiation in strongly coupled conformal field theories  

E-Print Network (OSTI)

Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled N=4 supersymmetric Yang-Mills theory. We compare the strong ...

Athanasiou, Christiana

328

Theory of localization and resonance phenomena in the quantum kicked rotor  

E-Print Network (OSTI)

We present an analytic theory of quantum interference and Anderson localization in the quantum kicked rotor (QKR). The behavior of the system is known to depend sensitively on the value of its effective Planck's constant $\\he$. We here show that for rational values of $\\he/(4\\pi)=p/q$, it bears similarity to a disordered metallic ring of circumference $q$ and threaded by an Aharonov-Bohm flux. Building on that correspondence, we obtain quantitative results for the time--dependent behavior of the QKR kinetic energy, $E(\\tilde t)$ (this is an observable which sensitively probes the system's localization properties). For values of $q$ smaller than the localization length $\\xi$, we obtain scaling $E(\\tilde t) \\sim \\Delta \\tilde t^2$, where $\\Delta=2\\pi/q$ is the quasi--energy level spacing on the ring. This scaling is indicative of a long time dynamics that is neither localized nor diffusive. For larger values $q\\gg \\xi$, the functions $E(\\tilde t)\\to \\xi^2$ saturates (up to exponentially small corrections $\\sim\\exp(-q/\\xi)$), thus reflecting essentially localized behavior.

C. Tian; A. Altland

2010-01-25T23:59:59.000Z

329

Quantum random walk of the field in an externally driven cavity  

E-Print Network (OSTI)

Using resonant interaction between atoms and the field in a high quality cavity, we show how to realize quantum random walks as proposed by Aharonov et al [Phys. Rev. A {\\bf48}, 1687 (1993)]. The atoms are driven strongly by a classical field. Under conditions of strong driving we could realize an effective interaction of the form $ iS^{x}(a-a^{\\dag})$ in terms of the spin operator associated with the two level atom and the field operators. This effective interaction generates displacement in the field's wavefunction depending on the state of the two level atom. Measurements of the state of the two level atom would then generate effective state of the field. Using a homodyne technique, the state of the quantum random walker can be monitored.

G S Agarwal; P K Pathak

2005-04-18T23:59:59.000Z

330

Quantum random walk of the field in an externally driven cavity  

E-Print Network (OSTI)

Using resonant interaction between atoms and the field in a high quality cavity, we show how to realize quantum random walks as proposed by Aharonov et al [Phys. Rev. A {\\bf48}, 1687 (1993)]. The atoms are driven strongly by a classical field. Under conditions of strong driving we could realize an effective interaction of the form $ iS^{x}(a-a^{\\dag})$ in terms of the spin operator associated with the two level atom and the field operators. This effective interaction generates displacement in the field's wavefunction depending on the state of the two level atom. Measurements of the state of the two level atom would then generate effective state of the field. Using a homodyne technique, the state of the quantum random walker can be monitored.

Agarwal, G S

2005-01-01T23:59:59.000Z

331

The Scalar Field Source in Kaluza-Klein Theory  

E-Print Network (OSTI)

To better understand the scalar field typical of higher-dimensional extensions of general relativity, we analyse three classes of solutions. In all, the field equation for the extra dimension resembles the Klein-Gordon equation, and we evaluate the strength of the source. Our results show that the scalar field is coupled to matter, and may be regarded as generating it.

Paul S. Wesson; James M. Overduin

2013-07-18T23:59:59.000Z

332

Quantum error control codes  

E-Print Network (OSTI)

It is conjectured that quantum computers are able to solve certain problems more quickly than any deterministic or probabilistic computer. For instance, Shor's algorithm is able to factor large integers in polynomial time on a quantum computer. A quantum computer exploits the rules of quantum mechanics to speed up computations. However, it is a formidable task to build a quantum computer, since the quantum mechanical systems storing the information unavoidably interact with their environment. Therefore, one has to mitigate the resulting noise and decoherence effects to avoid computational errors. In this dissertation, I study various aspects of quantum error control codes - the key component of fault-tolerant quantum information processing. I present the fundamental theory and necessary background of quantum codes and construct many families of quantum block and convolutional codes over finite fields, in addition to families of subsystem codes. This dissertation is organized into three parts: Quantum Block Codes. After introducing the theory of quantum block codes, I establish conditions when BCH codes are self-orthogonal (or dual-containing) with respect to Euclidean and Hermitian inner products. In particular, I derive two families of nonbinary quantum BCH codes using the stabilizer formalism. I study duadic codes and establish the existence of families of degenerate quantum codes, as well as families of quantum codes derived from projective geometries. Subsystem Codes. Subsystem codes form a new class of quantum codes in which the underlying classical codes do not need to be self-orthogonal. I give an introduction to subsystem codes and present several methods for subsystem code constructions. I derive families of subsystem codes from classical BCH and RS codes and establish a family of optimal MDS subsystem codes. I establish propagation rules of subsystem codes and construct tables of upper and lower bounds on subsystem code parameters. Quantum Convolutional Codes. Quantum convolutional codes are particularly well-suited for communication applications. I develop the theory of quantum convolutional codes and give families of quantum convolutional codes based on RS codes. Furthermore, I establish a bound on the code parameters of quantum convolutional codes - the generalized Singleton bound. I develop a general framework for deriving convolutional codes from block codes and use it to derive families of non-catastrophic quantum convolutional codes from BCH codes. The dissertation concludes with a discussion of some open problems.

Abdelhamid Awad Aly Ahmed, Sala

2008-05-01T23:59:59.000Z

333

A quantum top in a Casimir-induced quadrupole field  

E-Print Network (OSTI)

The Casimir energy is the change in energy of a configuration of objects due to second quantization of the electromagnetic field. The Casimir energy of a dielectric object inside a perfectly conducting sphere was recently ...

Fitzgerald, Eric Andrew Vitus

2011-01-01T23:59:59.000Z

334

Quantum ring solitons and nonlocal effects in plasma wake field excitations  

Science Conference Proceedings (OSTI)

A theoretical investigation of the quantum transverse beam motion for a cold relativistic charged particle beam travelling in a cold, collisionless, strongly magnetized plasma is carried out. This is done by taking into account both the individual quantum nature of the beam particles (single-particle uncertainty relations and spin) and the self consistent interaction generated by the plasma wake field excitation. By adopting a fluid model of a strongly magnetized plasma, the analysis is carried out in the overdense regime (dilute beams) and in the long beam limit. It is shown that the quantum description of the collective transverse beam dynamics is provided by a pair of coupled nonlinear governing equations. It comprises a Poisson-like equation for the plasma wake potential (driven by the beam density) and a 2D spinorial Schroedinger equation for the wave function, whose squared modulus is proportional to the beam density, that is obtained in the Hartree's mean field approximation, after disregarding the exchange interactions. The analysis of this pair of equations, which in general exhibits a strong nonlocal character, is carried out analytically as well as numerically in both the linear and the nonlinear regimes, showing the existence of the quantum beam vortices in the form of Laguerre-Gauss modes and ring envelope solitons, respectively. In particular, when the relation between the plasma wake field response and the beam probability density is strictly local, the pair of the governing equations is reduced to the 2D Gross-Pitaevskii equation that allows one to establish the conditions for the self focusing and collapse. These conditions include the quantum nature of the beam particles. Finally, when the relation between the plasma wake field response and the beam probability density is moderately nonlocal, the above pair of equations permits to follow the spatio-temporal evolution of a quantum ring envelope soliton. Such a structure exhibits small or violent breathing, but it remains very stable for long time.

Fedele, R.; Tanjia, F. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', and INFN, Napoli (Italy); De Nicola, S. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', and INFN, Napoli (Italy); Istituto Nazionale di Ottica - C. N. R., Pozzuoli (Italy); Jovanovic, D. [Institute of Physics, University of Belgrade, Belgrade (Serbia); Shukla, P. K. [Center of Advanced Studies in Physical Sciences, Ruhr-Universitaet Bochum, Bochum (Germany)

2012-10-15T23:59:59.000Z

335

Quantum Gravity: Has Spacetime Quantum Properties?  

E-Print Network (OSTI)

The incompatibility between GR and QM is generally seen as a sufficient motivation for the development of a theory of Quantum Gravity. If - so a typical argumentation - QM gives a universally valid basis for the description of all natural systems, then the gravitational field should have quantum properties. Together with the arguments against semi-classical theories of gravity, this leads to a strategy which takes a quantization of GR as the natural avenue to Quantum Gravity. And a quantization of the gravitational field would in some sense correspond to a quantization of geometry. Spacetime would have quantum properties. But, this strategy will only be successful, if gravity is a fundamental interaction. - What, if gravity is instead an intrinsically classical phenomenon? Then, if QM is nevertheless fundamentally valid, gravity can not be a fundamental interaction. An intrinsically classical gravity in a quantum world would have to be an emergent, induced or residual, macroscopic effect, caused by other interactions. The gravitational field (as well as spacetime) would not have any quantum properties. A quantization of GR would lead to artifacts without any relation to nature. The serious problems of all approaches to Quantum Gravity that start from a direct quantization of GR or try to capture the quantum properties of gravity in form of a 'graviton' dynamics - together with the, meanwhile, rich spectrum of approaches to an emergent gravity and/or spacetime - make this latter option more and more interesting for the development of a theory of Quantum Gravity. The most advanced emergent gravity (and spacetime) scenarios are of an information-theoretical, quantum-computational type.

Reiner Hedrich

2009-02-02T23:59:59.000Z

336

Quantum backreaction of massive fields and self-consistent semiclassical extreme black holes and acceleration horizons  

E-Print Network (OSTI)

We consider the effect of backreaction of quantized massive fields on the metric of extreme black holes (EBH). We find the analytical approximate expression for the stress-energy tensor for a scalar (with an arbitrary coupling), spinor and vector fields near an event horizon. We show that, independent of a concrete type of EBH, the energy measured by a freely falling observer is finite on the horizon, so that quantum backreaction is consistent with the existence of EBH. For the Reissner-Nordstrom EBH with a total mass M_{tot} and charge Q we show that for all cases of physical interest M_{tot}< Q. We also discuss different types of quantum-corrected Bertotti-Robinson spacetimes, find for them exact self-consistent solutions and consider situations in which tiny quantum corrections lead to the qualitative change of the classical geometry and topology. In all cases one should start not from a classical background with further adding quantum corrections but from the quantum-corrected self-consistent geometries from the very beginning.

J. Matyjasek; O. B. Zaslavskii

2001-02-27T23:59:59.000Z

337

A general theory of connectivity and current sheets in coronal magnetic fields anchored to discrete sources  

E-Print Network (OSTI)

A general theory of connectivity and current sheets in coronal magnetic fields anchored to discrete are current-free within each domain, and contain singular currents along each of the field's separators. 1 suggested, from reconnection along the single field line lying at the interface of the four resulting flux

Longcope, Dana

338

A GENERAL THEORY OF CONNECTIVITY AND CURRENT SHEETS IN CORONAL MAGNETIC FIELDS ANCHORED TO DISCRETE SOURCES  

E-Print Network (OSTI)

A GENERAL THEORY OF CONNECTIVITY AND CURRENT SHEETS IN CORONAL MAGNETIC FIELDS ANCHORED TO DISCRETE on the flux of each domain. The resulting equilibria are current-free within each domain and contain singular currents along each of the field's separators. Subject headings: MHD -- Sun: corona -- Sun: magnetic fields

Klapper, Isaac

339

Symmetries and vanishing couplings in string-derived low energy effective field theory  

Science Conference Proceedings (OSTI)

We study 4D low-energy effective field theory, derived from heterotic string theory on the orbifolds. In particular, we study Abelian and non-Abelian discrete symmetries and their anomalies. Furthermore, stringy computations also provide with stringy coupling selection rules.

Kobayashi, Tatsuo [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2012-07-27T23:59:59.000Z

340

Reliability of the Optimized Perturbation Theory for scalar fields at finite temperature  

Science Conference Proceedings (OSTI)

The thermodynamics of a massless scalar field with a quartic interaction is studied up to third order in the Optimized Perturbation Theory (OPT) method. A comparison with other nonperturbative approaches is performed such that the reliability of OPT is accessed.

Farias, R. L.; Teixeira, D. L. Jr. [Departamento de Ciencias Naturais, Universidade Federal de Sao Joao del Rei, 36301-000 Sao Joao del Rei, MG (Brazil); Ramos, R. O. [Departamento de Fisica Teorica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil)

2013-03-25T23:59:59.000Z

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


341

Spin-Gauge Theory of Gravity with Higgs-field Mechanism  

E-Print Network (OSTI)

We propose a Lorentz-covariant Yang-Mills spin-gauge theory, where the function valued Dirac matrices play the role of a non-scalar Higgs-field. As symmetry group we choose $SU(2) \\times U(1)$. After symmetry breaking a non-scalar Lorentz-covariant Higgs-field gravity appears, which can be interpreted within a classical limit as Einstein's metrical theory of gravity, where we restrict ourselves in a first step to its linearized version.

H. Dehnen; E. Hitzer

2013-06-10T23:59:59.000Z

342

Quantum Fields at Finite Temperature "from tera to nano Kelvin"  

E-Print Network (OSTI)

These lectures introduce techniques that are used in the description of systems of particles and fields at high temperature (or density). These methods have a broad range of physical applications. We shall discuss two specific applications: one related to hot and dense matter composed of quarks and gluons, with temperatures in the tera Kelvin range, the other related to Bose-Einstein condensation in ultra-cold gases, with temperatures in the nano Kelvin range. As we shall see, in both systems, long wavelength collective phenomena lead to similar features, in spite of the huge difference in orders of magnitude of the respective energy scales.

Jean-Paul Blaizot

2011-08-17T23:59:59.000Z

343

PERTURBATION-THEORY RULES FOR COMPUTING THE SELF-ENERGY OPERATOR IN QUANTUM STATISTICAL MECHANICS  

E-Print Network (OSTI)

J. Thouless) The Quantu~ Mechanics of V ~ny-Body Systems (IN QUANTUM STA TISTICAL MECHANICS Gordon BayrrL and AndrewIN QUANTUM STATISTICAL MECHANICS Gordon Baym and Andrew M.

Baym, Gordon

2008-01-01T23:59:59.000Z

344

Bosonic String and String Field Theory: a solution using the holomorphic representation  

E-Print Network (OSTI)

In this paper we show that the holomorphic representation is appropriate for description in a consistent way string and string field theories, when the considered number of component fields of the string field is finite. A new Lagrangian for the closed string is obtained and shown to be equivalent to Nambu-Goto's Lagrangian. We give the notion of anti-string, evaluate the propagator for the string field, and calculate the convolution of two of them.

Bollini, C G

2009-01-01T23:59:59.000Z

345

Theory and simulation of quantum photovoltaic devices based on the non-equilibrium Green's function formalism  

Science Conference Proceedings (OSTI)

This article reviews the application of the non-equilibrium Green's function formalism to the simulation of novel photovoltaic devices utilizing quantum confinement effects in low dimensional absorber structures. It covers well-known aspects of the fundamental ... Keywords: NEGF, Photovoltaics, Quantum dot, Quantum well

U. Aeberhard

2011-12-01T23:59:59.000Z

346

Quantum stabilizer codes and beyond  

E-Print Network (OSTI)

The importance of quantum error correction in paving the way to build a practical quantum computer is no longer in doubt. Despite the large body of literature in quantum coding theory, many important questions, especially those centering on the issue of "good codes" are unresolved. In this dissertation the dominant underlying theme is that of constructing good quantum codes. It approaches this problem from three rather different but not exclusive strategies. Broadly, its contribution to the theory of quantum error correction is threefold. Firstly, it extends the framework of an important class of quantum codes - nonbinary stabilizer codes. It clarifies the connections of stabilizer codes to classical codes over quadratic extension fields, provides many new constructions of quantum codes, and develops further the theory of optimal quantum codes and punctured quantum codes. In particular it provides many explicit constructions of stabilizer codes, most notably it simplifies the criteria by which quantum BCH codes can be constructed from classical codes. Secondly, it contributes to the theory of operator quantum error correcting codes also called as subsystem codes. These codes are expected to have efficient error recovery schemes than stabilizer codes. Prior to our work however, systematic methods to construct these codes were few and it was not clear how to fairly compare them with other classes of quantum codes. This dissertation develops a framework for study and analysis of subsystem codes using character theoretic methods. In particular, this work established a close link between subsystem codes and classical codes and it became clear that the subsystem codes can be constructed from arbitrary classical codes. Thirdly, it seeks to exploit the knowledge of noise to design efficient quantum codes and considers more realistic channels than the commonly studied depolarizing channel. It gives systematic constructions of asymmetric quantum stabilizer codes that exploit the asymmetry of errors in certain quantum channels. This approach is based on a Calderbank- Shor-Steane construction that combines BCH and finite geometry LDPC codes.

Sarvepalli, Pradeep Kiran

2008-08-01T23:59:59.000Z

347

Carrier energy spectrum and lifetime in quantum dots in electric field  

Science Conference Proceedings (OSTI)

The S-matrix formalism is used to perform analytical calculations of the spectrum of quasi-stationary states of charge carriers in a core-shell quantum dot. Analytical expressions are obtained for the second-order perturbative corrections to the position and half-width of a quasi-stationary energy level, and level shifts are calculated numerically for a core-shell quantum dot in the presence of an electrostatic field. The corrections to level half-width due to Stark effect are analyzed as functions of level energy and barrier thickness. It is shown that there exists a level position E{sub cr} such that the correction {delta}{gamma} to the level half-width changes sign. An analytical expression for the quadratic Stark shift in a dc-biased quantum well is found in semiclassical approximation. It is shown that the corresponding correction {delta}{gamma} to half-width also changes sign as energy passes through E{sub cr}. As an example, the Stark shift is calculated for a core-shell quantum dot in the electrostatic field of an adjacent protein molecule.

Zegrya, G. G., E-mail: zegrya@theory.ioffe.ru; Samosvat, D. M. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: samosvat@yandex.ru

2009-06-15T23:59:59.000Z

348

hep-th/0407046 Local Commutativity and Causality in Interacting PP-wave String Field Theory  

E-Print Network (OSTI)

Abstract: In this paper, we extend our previous study of causality and local commutativity of string fields in the pp-wave lightcone string field theory to include interaction. Contrary to the flat space case result of Lowe, Polchinski, Susskind, Thorlacius and Uglum, we found that the pp-wave interaction does not affect the local commutativity condition. Our results show that the pp-wave lightcone string field theory is not continuously connected with the flat space one. We also discuss the relation between the condition of local commutativity and causality. While the two notions are closely related in a point particle theory, their relation is less clear in string theory. We suggest that string local commutativity may be relevant for an operational defintion of causality using strings as

Chong-sun Chu; Konstantinos Kyritsis

2004-01-01T23:59:59.000Z

349

Applied Quantum Information Science  

Science Conference Proceedings (OSTI)

Applied Quantum Information Science. Summary: Theory is being developed and used to devise methods for preserving ...

2012-05-30T23:59:59.000Z

350

The Echo of the Quantum Bounce  

E-Print Network (OSTI)

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 will 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 will estimate an upper bound to the typical energy and length scales where quantum effects are relevant. We will 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

2013-08-20T23:59:59.000Z

351

Quantum Statistical Mechanics and Quantum Computation  

E-Print Network (OSTI)

Quantum Statistical Mechanics and Quantum Computation 22-23 March 2012 Room 111, Jadwin Hall, focused meeting to explore the intersection between quantum statistical mechanics and quantum computation, specifically quantum complexity theory. Advances in complexity theory have interesting implications for physics

352

Low energy effective actions and tachyon dynamics from string field theory  

E-Print Network (OSTI)

In this thesis we show how to calculate off-shell low energy effective actions and how to study the dynamics of the tachyon from string field theory. We discuss how to obtain an effective action for the massless field and ...

Coletti, Erasmo

2005-01-01T23:59:59.000Z

353

Heavy Quark Effective Theory, Interpolating Fields and Bethe-Salpeter Amplitudes  

E-Print Network (OSTI)

We use the LSZ reduction theorem and interpolating fields, alongwith the heavy quark effective theory, to investigate the structure of the Bethe-Salpeter amplitude for heavy hadrons. We show how a simple form of this amplitude, used extensively in heavy hadron decay calculations, follows naturally upto $O(1/M)$ from these field theoretic considerations.

F. Hussain; G. Thompson

1994-07-19T23:59:59.000Z

354

Geometric representation of the generator of duality in massless and massive p-form field theories  

Science Conference Proceedings (OSTI)

We study the invariance under duality transformations in massless and massive p-form field theories and obtain the Noether generators of the infinitesimal transformations that correspond to this symmetry. These generators can be realized in geometrical representations that generalize the loop representation of the Maxwell field, allowing for a geometrical interpretation which is studied.

Contreras, Ernesto; Martinez, Yisely [Grupo de Campos y Particulas, Facultad de Ciencias, Universidad Central de Venezuela, AP 47270, Caracas 1041 - A (Venezuela, Bolivarian Republic of); Leal, Lorenzo [Grupo de Campos y Particulas, Facultad de Ciencias, Universidad Central de Venezuela, AP 47270, Caracas 1041 - A (Venezuela, Bolivarian Republic of); Departamento de Fisica, Universidad Simon Bolivar, AP 89000, Caracas 1080 - A (Venezuela, Bolivarian Republic of)

2010-11-15T23:59:59.000Z

355

A Field Theory Model for Dark Matter and Dark Energy in Interaction  

E-Print Network (OSTI)

We propose a field theory model for dark energy and dark matter in interaction. Comparing the classical solutions of the field equations with the observations of the CMB shift parameter, BAO, lookback time and Gold supernovae sample, we observe a possible interaction between dark sectors with energy decay from dark energy into dark matter. The observed interaction provides an alleviation to the coincidence problem.

Sandro Micheletti; Elcio Abdalla; Bin Wang

2009-02-02T23:59:59.000Z

356

Quantum physics meets biology  

E-Print Network (OSTI)

Quantum physics and biology have long been regarded as unrelated disciplines, describing nature at the inanimate microlevel on the one hand and living species on the other hand. Over the last decades the life sciences have succeeded in providing ever more and refined explanations of macroscopic phenomena that were based on an improved understanding of molecular structures and mechanisms. Simultaneously, quantum physics, originally rooted in a world view of quantum coherences, entanglement and other non-classical effects, has been heading towards systems of increasing complexity. The present perspective article shall serve as a pedestrian guide to the growing interconnections between the two fields. We recapitulate the generic and sometimes unintuitive characteristics of quantum physics and point to a number of applications in the life sciences. We discuss our criteria for a future quantum biology, its current status, recent experimental progress and also the restrictions that nature imposes on bold extrapolations of quantum theory to macroscopic phenomena.

Markus Arndt; Thomas Juffmann; Vlatko Vedral

2009-11-01T23:59:59.000Z

357

Quantum Histories and Quantum Gravity  

E-Print Network (OSTI)

This paper reviews the histories approach to quantum mechanics. This discussion is then applied to theories of quantum gravity. It is argued that some of the quantum histories must approximate (in a suitable sense) to classical histories, if the correct classical regime is to be recovered. This observation has significance for the formulation of new theories (such as quantum gravity theories) as it puts a constraint on the kinematics, if the quantum/classical correspondence principle is to be preserved. Consequences for quantum gravity, particularly for Lorentz symmetry and the idea of "emergent geometry", are discussed.

Joe Henson

2009-01-26T23:59:59.000Z

358

Effects of external fields on the excitonic emission from single InAs/GaAs quantum dots  

Science Conference Proceedings (OSTI)

A low-temperature micro-photoluminescence (?-PL) investigation of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field is reported. It is demonstrated that the QDs PL signal could be increased several times by altering the ... Keywords: Exciton, Micro-luminescence, Quantum dot

P. O. Holtz; E. S. Moskalenko; M. Larsson; K. F. Karlsson; W. V. Schoenfeld; P. M. Petroff

2008-03-01T23:59:59.000Z

359

Non Archimedean Pseudodifferential Equations of Klein-Gordon Type and Quantum Scalar Fields  

E-Print Network (OSTI)

In this article we introduce a new class of non Archimedean pseudodifferential equations of Klein-Gordon type whose solutions can be easily quantized using the machinery of the second quantization. We study the Cauchy problem for these equations. We present a `semi-formal' constructruction, on the p-adic Minkowski space, of the neutral and charged quantum scalar fields having a nonzero p-adic number as mass parameter.

W. A. Zuniga-Galindo

2013-02-14T23:59:59.000Z

360

Sound relativistic quantum mechanics for a strictly solitary nonzero-mass particle, and its quantum-field reverberations  

E-Print Network (OSTI)

It is generally acknowledged that neither the Klein-Gordon equation nor the Dirac Hamiltonian can produce sound solitary-particle relativistic quantum mechanics due to the ill effects of their negative-energy solutions; instead their field-quantized wavefunctions are reinterpreted as dealing with particle and antiparticle simultaneously--despite the clear physical distinguishability of antiparticle from particle and the empirically known slight breaking of the underlying CP invariance. The natural square-root Hamiltonian of the free relativistic solitary particle is iterated to obtain the Klein-Gordon equation and linearized to obtain the Dirac Hamiltonian, steps that have calculational but not physical motivation, and which generate the above-mentioned problematic negative-energy solutions as extraneous artifacts. Since the natural square root Hamiltonian for the free relativistic solitary particle contrariwise produces physically unexceptionable quantum mechanics, this article focuses on extending that Hamiltonian to describe a solitary particle (of either spin 0 or spin one-half) in relativistic interaction with an external electromagnetic field. That is achieved by use of Lorentz-covariant solitary-particle four momentum techniques together with the assumption that well-known nonrelativistic dynamics applies in the particle's rest frame. Lorentz-invariant solitary particle actions, whose formal Hamiltonization is an equivalent alternative approach, are as well explicitly displayed. It is proposed that two separate solitary-particle wavefunctions, one for a particle and the other for its antiparticle, be independently quantized in lieu of "reinterpreting" negative energy solutions--which indeed don't even afflict proper solitary particles.

Steven Kenneth Kauffmann

2009-09-22T23:59:59.000Z

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


361

Electromagnetic and gravitational self-force on a relativistic particle from quantum fields in curved space  

E-Print Network (OSTI)

We provide a quantum field theoretical derivation of the Abraham-Lorentz-Dirac (ALD) equation, describing the motion of an electric point charge sourcing an electromagnetic field, which back-reacts on the charge as a self-force, and the Mino-Sasaki-Tanaka-Quinn-Wald (MSTQW) equation describing the motion of a point mass with self-force interacting with the linearized metric perturbations caused by the mass off an otherwise vacuous curved background spacetime. We regularize the formally divergent self-force by smearing the direct part of the retarded Green's function and using a quasilocal expansion. We also derive the ALD-Langevin and the MSTQW-Langevin equations with a classical stochastic force accounting for the effect of the quantum fluctuations in the field, which causes small fluctuations on the particle trajectory. These equations will be useful for studying the stochastic motion of charges and small masses under the influence of both quantum and classical noise sources, derived either self-consistently or put in by hand phenomenologically. We also show that history-dependent noise-induced drift motions could arise from such stochastic sources on the trajectory that could be a hidden feature of gravitational wave forms hitherto unknown.

Chad R. Galley; B. L. Hu; Shih-Yuin Lin

2006-03-24T23:59:59.000Z

362

Dynamic Phase Transitions In The Spin-2 Ising System Under An Oscillating Magnetic Field Within The Effective-Field Theory  

SciTech Connect

The dynamic phase transitions are studied in the spin-2 Ising model under a time-dependent oscillating magnetic field by using the effective-field theory with correlations. The effective-field dynamic equation is derived by employing the Glauber transition rates and the phases in the system are obtained by solving this dynamic equation. The nature (first- or second-order) of the dynamic phase transition is characterized by investigating the thermal behavior of the dynamic order parameter and the dynamic phase transition temperatures are obtained. The dynamic phase diagrams are presented in (T/zJ, h/zJ) plane.

Ertas, Mehmet; Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Deviren, Bayram [Department of Physics, Nevsehir University, 50300 Nevsehir (Turkey)

2010-12-23T23:59:59.000Z

363

Theory of Electro-optic Modulation via a Quantum Dot Coupled to a Nano-resonator  

E-Print Network (OSTI)

In this paper, we analyze the performance of an electro-optic modulator based on a single quantum dot strongly coupled to a nano-resonator, where electrical control of the quantum dot frequency is achieved via quantum confined Stark effect. Using realistic system parameters, we show that modulation speeds of a few tens of GHz are achievable with this system, while the energy per switching operation can be as small as 0.5 fJ. In addition, we study the non-linear distortion, and the effect of pure quantum dot dephasing on the performance of the modulator.

Arka Majumdar; Nicolas Manquest; Andrei Faraon; Jelena Vuckovic

2009-11-27T23:59:59.000Z

364

Finite temperature solitons in nonlocal field theories from p-adic strings  

Science Conference Proceedings (OSTI)

Nonlocal field theories which arise from p-adic string theories have vacuum soliton solutions. We find the soliton solutions at finite temperature. These solutions become important for the partition function when the temperature exceeds m{sub s}/g{sub o}{sup 2}, where m{sub s} is the string mass scale and g{sub o} is the open string coupling.

Biswas, Tirthabir [Department of Physics, St. Cloud State University, St. Cloud, Minnesota 56301 (United States); Cembranos, Jose A. R. [William I. Fine Theoretical Physics Institute, University of Minnesota, Minneapolis, Minnesota 55455 (United States); School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Kapusta, Joseph I. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2010-10-15T23:59:59.000Z

365

Mass Spectra in the Doubly Symmetric Theory of Infinite-Component Fields  

E-Print Network (OSTI)

We consider the problem of the characteristics of mass spectra in the doubly symmetric theory of fields transforming under the proper Lorentz group representations decomposable into an infinite direct sum of finite-dimensional irreducible representations. We show that there exists a range of free parameters of the theory where the mass spectra of fermions are quite satisfactory from the physical standpoint and correspond to the picture expected in the parton model of hadrons.

L. M. Slad

2003-12-13T23:59:59.000Z

366

Retrieving Storm Electric Fields from Aircraft Field Mill Data. Part I: Theory  

Science Conference Proceedings (OSTI)

It is shown that the problem of retrieving storm electric fields from an aircraft instrumented with several electric field mill sensors can be expressed in terms of a standard Lagrange multiplier optimization problem. The method naturally removes ...

W. J. Koshak

2006-10-01T23:59:59.000Z

367

Bound-state field theory approach to proton structure effects in muonic hydrogen  

E-Print Network (OSTI)

A bound-state field theory approach to muonic hydrogen is set up using a variant of the Furry representation in which the lowest-order Hamiltonian describes a muon in the presence of a point Coulomb field, but the origin of the binding field is taken to be three charged quarks in the proton which are modeled as Dirac particles that move freely within a spherical well. Bound-state field theory techniques are used to evaluate one- and two-photon effects. Particular attention is paid to two-photon exchange diagrams, which include the effect of proton polarizability. In addition the modification of the electromagnetic self energy of the proton by the electric field of the muon is examined. Finally, the model is used to carry out a calculation of the static electric polarizability of the proton.

Peter J. Mohr; J. Griffith; J. Sapirstein

2013-04-07T23:59:59.000Z

368

Mass gap in quantum energy-mass spectrum of relativistic Yang-Mills fields  

E-Print Network (OSTI)

A non-perturbative relativistic quantum Yang-Mills theory with a semisimple compact gauge Lie group on the four-dimensional Minkowski spacetime is set up in a Schroedinger representation with infinite-dimensional differential operators in the framework of sesqui-holomorphic nuclear Kree-Gelfand triples. The \\emph{linear} quantum Yang-Mills energy-mass operator $\\mathbf{H}$ is defined as the anti-normal quantization of the \\emph{non-linear} Yang-Mills energy-mass functional of Cauchy data supported by a ball $\\mathbb{B}(R)$ with the center at the origin of $\\mathbb{R}^3$ and the variable radius R>0. The general global solution of the non-linear Yang-Mills system of partial differential equations (with no restrictions at infinity) is reduced to the solution of the initial value problems in the temporal gauge with the Cauchy data supported by the balls $\\mathbb{B}(R)$. It is shown that $\\mathbf{H}$ dominates the number operator $\\mathbf{N}$. Since 0 is the spectral infimum of $\\mathbf{H}$ and, simultaneously, the simple fundamental eigenvalue of $N$, variational spectral principles imply that 0 is the simple fundamental eigenvalue of $N$ as well. Thus $\\mathbf{H}$ has a positive mass gap. The domination proof depends crucially on the magic of the Killing quadratic form that reveals a mass quadratic form in the Weyl symbol of $\\mathbf{H}$. With a dimensional transmutation of the coupling constant, the mass gap is proportional to 1/R and the running coupling constant is proportional to $\\sqrt{R}$. The inverse dependence demonstrates an asymptotic freedom for quantum Yang-Mills self-interaction at short distances. The mathematically rigorous theory is non-perturbative and provides a solution for the 7th Clay Institute Millennium problem.

Alexander Dynin

2013-08-29T23:59:59.000Z

369

A statistical field theory approach applied to the liquid vapor interface  

E-Print Network (OSTI)

Last years, there has been a renewed interest in the utilization of statistical field theory methods for the description of systems at equilibrium both in the vicinity and away from critical points, in particular in the field of liquid state physics. These works deal in general with homogeneous systems, although recently the study of liquids in the vicinity of hard walls has also been considered in this way. On the other hand, effective Hamiltonian pertaining to the $\\phi^4$ theory family have been written and extensively used for the description of inhomogeneous systems either at the simple interface between equilibrium phases or for the description of wetting. In the present work, we focus on a field theoretical description of the liquid vapor interface of simple fluids. We start from the representation of the grand partition function obtained from the Hubbard-Stratonovich transform leading to an exact formulation of the problem, namely neither introducing an effective Hamiltonian nor associating the field to the one-body density of the liquid. Using as a reference system the hard sphere fluid and imposing the coexistence condition, the expansion of the Hamiltonian obtained yields a usual $\\phi^4$ theory without unknown parameter. An important point is that the so-called capillary wave theory appears as an approximation of the one-loop theory in the functional expansion of the Hamiltonian, without any need to an underlying phenomenology.

Vincent Russier; Jean-Michel Caillol

2009-07-16T23:59:59.000Z

370

Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies  

E-Print Network (OSTI)

We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory (QFT). QFT properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in QFT including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects.

Mehdi Ahmadi; David Edward Bruschi; Nicolai Friis; Carlos Sabn; Gerardo Adesso; Ivette Fuentes

2013-07-26T23:59:59.000Z

371

BRST quantization of a sixth-order derivative scalar field theory  

E-Print Network (OSTI)

We study a sixth order derivative scalar field model in Minkowski spacetime as a toy model of higher-derivative critical gravity theories. This model is consistently quantized when using the Becchi-Rouet-Stora-Tyutin (BRST) quantization scheme even though it does not show gauge symmetry manifestly. Imposing a BRST quartet generated by two scalars and ghosts, there remains a non-trivial subspace with positive norm. This might be interpreted as a Minkowskian dual version of the unitary truncation in the logarithmic conformal field theory.

Yong-Wan Kim; Yun Soo Myung; Young-Jai Park

2013-05-31T23:59:59.000Z

372

Yang-Mills Gauge Conditions from Witten's Open String Field Theory  

E-Print Network (OSTI)

We construct the Zinn-Justin-Batalin-Vilkovisky action for tachyons and gauge bosons from Witten's 3-string vertex of the bosonic open string without gauge fixing. Through canonical transformations, we find the off-shell, local, gauge-covariant action up to 3-point terms, satisfying the usual field theory gauge transformations. Perturbatively, it can be extended to higher-point terms. It also gives a new gauge condition in field theory which corresponds to the Feynman-Siegel gauge on the world-sheet.

Haidong Feng; Warren Siegel

2006-11-28T23:59:59.000Z

373

Quantum Tachyon Dynamics  

E-Print Network (OSTI)

It is suggested that charged tachyons of extremely large mass M could not only contribute to the dark matter needed to fit astrophysical observations, but could also provide an explanation for gamma ray bursts and ultra high energy cosmic rays. The present paper defines a quantum field theory of tachyons, the latter similar to ordinary leptons, but with momenta larger than energy.

H. M. Fried; Y. Gabellini

2005-05-31T23:59:59.000Z

374

Quantum Thermodynamics  

E-Print Network (OSTI)

Quantum thermodynamics addresses the emergence of thermodynamical laws from quantum mechanics. The link is based on the intimate connection of quantum thermodynamics with the theory of open quantum systems. Quantum mechanics inserts dynamics into thermodynamics giving a sound foundation to finite-time-thermodynamics. The emergence of the 0-law I-law II-law and III-law of thermodynamics from quantum considerations is presented. The emphasis is on consistence between the two theories which address the same subject from different foundations. We claim that inconsistency is the result of faulty analysis pointing to flaws in approximations.

Ronnie Kosloff

2013-05-10T23:59:59.000Z

375

Simulating chemistry using quantum computers  

E-Print Network (OSTI)

The difficulty of simulating quantum systems, well-known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, now a well-established field, have been applied to chemical problems. We describe algorithms that achieve significant advantages for the electronic-structure problem, the simulation of chemical dynamics, protein folding, and other tasks. Although theory is still ahead of experiment, we outline recent advances that have led to the first chemical calculations on small quantum information processors.

Ivan Kassal; James D. Whitfield; Alejandro Perdomo-Ortiz; Man-Hong Yung; Aln Aspuru-Guzik

2010-07-15T23:59:59.000Z

376

Intervalley splittings of Si quantum wells  

E-Print Network (OSTI)

Multi-valley effective mass theory for silicon quantum well structure is studied taking into account the external fields and the quantum interfaces. It is found that the phenomenological delta function potential, employed to explain the valley splitting caused by the quantum well interface in the previous work [Ref. 10], can be derived self-consistently from the multi-valley effective mass theory. Finite element method is used to solve the multi-valley effective equations. Theoretical predictions are in a reasonably good agreement with the recent experimental observation of valley splitting in a SiO_{2}/Si/SiO_{2} quantum well, which prove the validity of our approach.

S. -H. Park; Y. Y. Lee; Doyeol Ahn

2007-11-05T23:59:59.000Z

377

Report of the Snowmass 2013 Computing Frontier working group on Lattice Field Theory -- Lattice field theory for the energy and intensity frontiers: Scientific goals and computing needs  

E-Print Network (OSTI)

This is the report of the Computing Frontier working group on Lattice Field Theory prepared for the proceedings of the 2013 Community Summer Study ("Snowmass"). We present the future computing needs and plans of the U.S. lattice gauge theory community and argue that continued support of the U.S. (and worldwide) lattice-QCD effort is essential to fully capitalize on the enormous investment in the high-energy physics experimental program. We first summarize the dramatic progress of numerical lattice-QCD simulations in the past decade, with some emphasis on calculations carried out under the auspices of the U.S. Lattice-QCD Collaboration, and describe a broad program of lattice-QCD calculations that will be relevant for future experiments at the intensity and energy frontiers. We then present details of the computational hardware and software resources needed to undertake these calculations.

Blum, T; Holmgren, D; Brower, R; Catterall, S; Christ, N; Kronfeld, A; Kuti, J; Mackenzie, P; Neil, E T; Sharpe, S R; Sugar, R

2013-01-01T23:59:59.000Z

378

Report of the Snowmass 2013 Computing Frontier working group on Lattice Field Theory -- Lattice field theory for the energy and intensity frontiers: Scientific goals and computing needs  

E-Print Network (OSTI)

This is the report of the Computing Frontier working group on Lattice Field Theory prepared for the proceedings of the 2013 Community Summer Study ("Snowmass"). We present the future computing needs and plans of the U.S. lattice gauge theory community and argue that continued support of the U.S. (and worldwide) lattice-QCD effort is essential to fully capitalize on the enormous investment in the high-energy physics experimental program. We first summarize the dramatic progress of numerical lattice-QCD simulations in the past decade, with some emphasis on calculations carried out under the auspices of the U.S. Lattice-QCD Collaboration, and describe a broad program of lattice-QCD calculations that will be relevant for future experiments at the intensity and energy frontiers. We then present details of the computational hardware and software resources needed to undertake these calculations.

T. Blum; R. S. Van de Water; D. Holmgren; R. Brower; S. Catterall; N. Christ; A. Kronfeld; J. Kuti; P. Mackenzie; E. T. Neil; S. R. Sharpe; R. Sugar

2013-10-23T23:59:59.000Z

379

Quantum-Classical Correspondence in Nonrelativistic Electrodynamics  

SciTech Connect

A form of classical electrodynamic field exists which gives exact agreement with the operator field of quantum electrodynamics (QED) for the Lamb shift of a harmonically bound point electron. Here it is pointed out that this form of classical theory with its physically acceptable interpretation is the result of an unconventional resolution of a mathematically ambiguous term in classical field theory. Finally a quantum-classical correspondence principle is shown to exist in the sense that the classical field and expectation value of the QED operator field are identical if retardation is neglected in the latter.

Ritchie, A.B.; Weatherford, C.A.

1999-10-14T23:59:59.000Z

380

Quantum classical correspondence in nonrelativistic electrodynamics  

SciTech Connect

A form of classical electrodynamic field exists which gives exact agreement with the operator field of quantum electrodynamics (QED) for the Lamb shift of a harmonically bound point electron. Here it is pointed out that this form of classical theory, with its physically acceptable interpretation, is the result of an unconventional resolution of a mathematically ambiguous term in classical field theory. Finally, a quantum classical correspondence principle is shown to exist in the sense that the classical field and expectation value of the QED operator field are identical, if retardation is neglected in the latter.

Ritchie, B.; Weatherford, C.A.

1999-12-01T23:59:59.000Z

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


381

Stochastic Force Due to a Quantum Scalar Field in Minkowski Spacetime  

E-Print Network (OSTI)

A method is presented for computing approximate expressions for the stochastic force term $\\xi_{ab}$ which appears in the Einstein-Langevin equation of stochastic gravity. Within this framework, $\\xi_{ab}$ is a stochastic tensor field whose probability distribution mimics the probability distribution of the fluctuations of the quantum stress tensor operator; it is defined to be a random tensor field of zero mean whose correlation function is given by the expectation value of the symmetrized two point function of the stress energy fluctuation operator, called the noise kernel. Approximate expressions are obtained by means of a truncated Karhunen-Loeve transform defined on a random lattice of spacetime points. Due to the singular nature of the noise kernel, a coarse graining procedure is used to regulate divergences; as a result, the expressions obtained for $\\xi_{ab}$ approximate values which might be seen by a probe measuring fluctuations in the stress energy using a sampling profile of finite width. Two realizations of $\\xi_{ab}$ in Minkowski spacetime for the conformally invariant quantum scalar field in the Minkowski vacuum state are presented.

Jason D. Bates

2013-03-07T23:59:59.000Z

382

From surface operators to non-Abelian volume operators in puff field theory  

Science Conference Proceedings (OSTI)

Puff field theory (PFT) is a low energy decoupling regime of string theory that still retains the nonlocal attributes of the parent theory--while preserving isotropy for its nonlocal degrees of freedom. It realizes an extended holographic dictionary at strong coupling and dynamical nonlocal states akin to defects or the surface operators of local gauge theories. In this work, we probe the nonlocal features of PFT using D3 branes. We find supersymmetric configurations that end on defects endowed with non-Abelian degrees of freedom. These are 2+1 dimensional defects in the 3+1 dimensional PFT that may be viewed as volume operators. We determine their R charge, vacuum expectation value, energy, and gauge group structure.

Sahakian, Vatche [Harvey Mudd College, Claremont, California 91711 (United States) and California Institute of Technology, Pasadena, California 91125 (United States)

2010-06-15T23:59:59.000Z

383

Senses in which Quantum Theory is an Analogy for Information Retrieval and Science  

E-Print Network (OSTI)

Arafat,S. Proceedings of the Fifth Quantum Interaction Symposium (QI 2011), 27-29 June 2011, Aberdeen, Scotland. Vol 7052. Lecture Notes in Computer Science (LNCS) ed.; 2011. pp 161-71 Springer

Arafat, S.

384

A test of Einstein's theory of gravitation: Velocity distribution of low-energy particles in a spherically symmetric gravitational field  

E-Print Network (OSTI)

We propose a new test of Einstein's theory of gravitation. It concerns the velocity distribution of low-energy particles in a spherically symmetric gravitational field.

Jian-Miin Liu

2002-06-17T23:59:59.000Z

385

W-algebras arising as chiral algebras of conformal field theory  

E-Print Network (OSTI)

It is argued that chiral algebras of conformal field theory possess a W-algebra structure. A survey of explicitly known W-algebras and their constructions is given. (Talk given at the XIX International Colloquium on ``Group Theoretical Methods in Physics'', Salamanca, Spain, June 29 -- July 4, 1992)

Kausch, H G

1992-01-01T23:59:59.000Z

386

Particle production in field theories coupled to strong external sources. II: Generating functions  

E-Print Network (OSTI)

We discuss a method for computing the generating function for the multiplicity distribution in field theories with strong time dependent external sources. At leading order, the computation of the generating function reduces to finding a pair of solutions of the classical equations of motion, with non-standard temporal boundary conditions.

Francois Gelis; Raju Venugopalan

2006-05-23T23:59:59.000Z

387

Quantum control with noisy fields: computational complexity vs. sensitivity to noise  

E-Print Network (OSTI)

A closed quantum system is defined as completely controllable if an arbitrary unitary transformation can be executed using the available controls. In practice, control fields are a source of unavoidable noise, which has to be suppressed to retain controllability. Can one design control fields such that the effect of noise is negligible on the time-scale of the transformation? This question is intimately related to the fundamental problem of a connection between the computational complexity of the control problem and the sensitivity of the controlled system to noise. The present study considers a paradigm of control, where the Lie-algebraic structure of the control Hamiltonian is fixed, while the size of the system increases with the dimension of the Hilbert space representation of the algebra. We find two types of control tasks, easy and hard. Easy tasks are characterized by a small variance of the evolving state with respect to the operators of the control operators. They are relatively immune to noise and the control field is easy to find. Hard tasks have a large variance, are sensitive to noise and the control field is hard to find. The influence of noise increases with the size of the system, which is measured by the scaling factor $N$ of the largest weight of the representation. For fixed time and control field as O(N) for easy tasks and as $O(N^2)$ for hard tasks. As a consequence, even in the most favorable estimate, for large quantum systems, generic noise in the controls dominates for a typical class of target transformations, i.e., complete controllability is destroyed by noise.

S. Kallush; M. Khasin; R. Kosloff

2013-08-28T23:59:59.000Z

388

Quantum interference and control of the dynamic Franz-Keldysh effect: Generation and detection of terahertz space-charge fields  

Science Conference Proceedings (OSTI)

The Dynamic Franz Keldysh Effect (DFKE) is produced and controlled in bulk gallium arsenide by quantum interference without the aid of externally applied fields and is spatially and temporally resolved using ellipsometric pump-probe techniques. The {approx}3 THz internal driving field for the DFKE is a transient space-charge field that is associated with a critically damped coherent plasma oscillation produced by oppositely traveling ballistic electron and hole currents that are injected by two-color quantum interference techniques. The relative phase and polarization of the two pump pulses can be used to control the DFKE.

Wang, Rui [Laboratory for Photonics and Quantum Electronics, 138 IATL, University of Iowa, Iowa City, Iowa 52242 (United States) [Laboratory for Photonics and Quantum Electronics, 138 IATL, University of Iowa, Iowa City, Iowa 52242 (United States); Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States); Jacobs, Paul; Smirl, Arthur L. [Laboratory for Photonics and Quantum Electronics, 138 IATL, University of Iowa, Iowa City, Iowa 52242 (United States)] [Laboratory for Photonics and Quantum Electronics, 138 IATL, University of Iowa, Iowa City, Iowa 52242 (United States); Zhao, Hui [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States)] [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States)

2013-06-24T23:59:59.000Z

389

Fundamental constants in effective theory  

E-Print Network (OSTI)

There is a discussion between L. B. Okun, G. Veneziano and M. J. Duff, concerning the number of fundamental dimensionful constants in physics [1]. They advocated correspondingly 3, 2 and 0 fundamental constants. Here we consider this problem on example of the effective relativistic quantum field theory, which emerges in the low energy corner of quantum liquids and which reproduces many features of our physics including chiral fermions, gauge fields and dynamical gravity. 1 Introduction. The effective relativistic quantum field theory (RQFT) arising as emergent phenomenon in quantum liquids [2], or in other condensed matter systems [3], allows us to look at the problem of fundamental constants from the outside, i.e. from the point of view of an external observer who does not

G. E. Volovik

2008-01-01T23:59:59.000Z

390

Thermodynamics of space quanta models quantum gravity  

E-Print Network (OSTI)

Canonically quantized 3+1 general relativity with the global one dimensionality (1D) conjecture defines the model, which dimensionally reduced and secondary quantized yields the 1D quantum field theory wherein generic one-point correlations create physical scales. This simple quantum gravity model, however, can be developed in a wider sense. In this paper we propose to consider ab initio thermodynamics of space quanta as the quantum gravity phenomenology. The thermodynamics is constructed in the entropic formalism.

L. A. Glinka

2009-06-20T23:59:59.000Z

391

A General Systems Theory for Chaos, Quantum Mechanics and Gravity for Dynamical Systems of all Space-Time Scales  

E-Print Network (OSTI)

Non-local connections, i. e. long-range space-time correlations intrinsic to the observed subatomic dynamics of quantum systems is also exhibited by macro-scale dynamical systems as selfsimilar fractal space-time fluctuations and is identified as self-organized criticality. The author has developed a general systems theory for the observed self-organized criticality applicable to dynamical systems of all space-time scales based on the concept that spatial integration of enclosed small-scale fluctuations results in the formation of large eddy circulation. The eddy energy spectrum therefore represents the statistical normal distribution according to the Central Limit Theorem. The additive amplitudes of eddies, when squared (variance or eddy kinetic energy), represent the statistical normal (probability) distribution, a result observed in the subatomic dynamics of quantum systems. The model predicts Kepler's laws of planetary motion for eddy circulation dynamics. Inverse square law of gravitation therefore applies to the eddy continuum ranging from subatomic to macro-scale dynamical systems, e.g. weather systems. The model is similar to a superstring model for subatomic dynamics which unifies quantum mechanical and classical concepts and manifestation of matter is visualised as vibrational modes in string-like energy flow patterns. The cumulative sum of centripetal forces in a hierarchy of vortex circulations may result in the observed inverse square law form for gravitational attraction between inertial masses of the eddies.

A M Selvam

2005-03-03T23:59:59.000Z

392

Quantum chromodynamics and nuclear physics at extreme energy density. Progress report, May 15, 1993--May 14, 1994  

SciTech Connect

This report briefly discusses the following topics: quark-gluon plasma and high-energy collisions; hadron structure and chiral dynamics; nonperturbative studies and nonabelian gauge theories; and studies in quantum field theory.

Mueller, B.; Springer, R.P.

1994-05-15T23:59:59.000Z

393

Spherically symmetric solutions of modified field equations in f(R) theories of gravity  

E-Print Network (OSTI)

Spherically symmetric static empty space solutions are studied in f(R) theories of gravity. We reduce the set of modified Einstein's equations to a single equation and show how one can construct exact solutions in different f(R) models. In particular, we show that for a large class models, including e.g. the f(R)=R-\\mu^4/R model, the Schwarzschild-de Sitter metric is an exact solution of the field equations. The significance of these solutions is discussed in light of solar system constraints on $f(R)$ theories of gravity.

Tuomas Multamaki; Iiro Vilja

2006-06-15T23:59:59.000Z

394

Boundary S Matrix and the Anti{endash}de Sitter Space to Conformal Field Theory Dictionary  

Science Conference Proceedings (OSTI)

An S matrix analog is defined for anti{endash}de Sitter (Ads) space by constructing {open_quotes}in{close_quotes} and {open_quotes}out{close_quotes} states that asymptote to the timelike boundary. A derivation parallel to that of the Lehmann-Symanzik-Zimmermann formula shows that this {open_quotes}boundary S matrix{close_quotes} is given directly by correlation functions in the boundary conformal theory. This provides a key entry in the AdS to conformal field theory dictionary. {copyright} {ital 1999} {ital The American Physical Society }

Giddings, S.B. [Department of Physics, University of California, Santa Barbara, California 93106-9530 (United States)

1999-10-01T23:59:59.000Z

395

Information field theory for cosmological perturbation reconstruction and nonlinear signal analysis  

SciTech Connect

We develop information field theory (IFT) as a means of Bayesian inference on spatially distributed signals, the information fields. A didactical approach is attempted. Starting from general considerations on the nature of measurements, signals, noise, and their relation to a physical reality, we derive the information Hamiltonian, the source field, propagator, and interaction terms. Free IFT reproduces the well-known Wiener-filter theory. Interacting IFT can be diagrammatically expanded, for which we provide the Feynman rules in position-, Fourier-, and spherical-harmonics space, and the Boltzmann-Shannon information measure. The theory should be applicable in many fields. However, here, two cosmological signal recovery problems are discussed in their IFT formulation. (1) Reconstruction of the cosmic large-scale structure matter distribution from discrete galaxy counts in incomplete galaxy surveys within a simple model of galaxy formation. We show that a Gaussian signal, which should resemble the initial density perturbations of the Universe, observed with a strongly nonlinear, incomplete and Poissonian-noise affected response, as the processes of structure and galaxy formation and observations provide, can be reconstructed thanks to the virtue of a response-renormalization flow equation. (2) We design a filter to detect local nonlinearities in the cosmic microwave background, which are predicted from some early-Universe inflationary scenarios, and expected due to measurement imperfections. This filter is the optimal Bayes' estimator up to linear order in the nonlinearity parameter and can be used even to construct sky maps of nonlinearities in the data.

Ensslin, Torsten A.; Frommert, Mona; Kitaura, Francisco S. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Strasse 1, 85741 Garching (Germany)

2009-11-15T23:59:59.000Z

396

Breakdown of time-dependent mean-field theory for a one-dimensional condensate of impenetrable bosons  

E-Print Network (OSTI)

We show that the time-dependent nonlinear Schrodinger equation of mean-field theory has limited utility for a one-dimensional condensate of impenetrable bosons. Mean-field theory with its associated order parameter predicts interference between split condensates that are recombined, whereas an exact many-body treatment shows minimal interference.

M. D. Girardeau; E. M. Wright

2000-02-25T23:59:59.000Z

397

Thermalized Non-Equilibrated Matter against Random Matrix Theory, Quantum Chaos and Direct Interaction: Warming up  

E-Print Network (OSTI)

The idea of a thermalized non-equilibrated state of matter offers a conceptually new understanding of the strong angular asymmetry. In this compact review we present some clarifications, corrections and further developments of the approach, and provide a brief account of results previously discussed but not reported in the literature. The cross symmetry compound nucleus $S$-matrix correlations are obtained (i) starting from the unitary $S$-matrix representation, (ii) by explicitly taking into account a process of energy equilibration, and (iii) without taking the thermodynamic limit of an infinite number of particles in the thermalized system. It is conjectured that the long phase memory is due to the exponentially small total spin off-diagonal resonance intensity correlations. This manifestly implies that the strong angular asymmetry intimately relates to extremely small deviations of the eigenfunction distribution from Gaussian law. The spin diagonal resonance intensity correlations determine a new time/energy scale for a validity of random matrix theory. Its definition does not involve overlaps of the many-body interacting configurations with shell model non-interacting states and thus is conceptually different from the physical meaning (inverse energy relaxation time) of the spreading widths introduced by Wigner. Exact Gaussian distribution of the resonance wave functions corresponds to the instantaneous phase relaxation. We invite the nuclear reaction community for the competition to describe, as the first challenge, the strong forward peaking in the typically evaporation part of the proton spectra. This is necessary to initiate revealing long-term misconduct in the heavily cross-disciplinary field, also important for nuclear industry applications.

S. Kun; Y. Li; M. H. Zhao; M. R. Huang

2013-07-17T23:59:59.000Z

398

Lattice Calculation of Thermal Properties of Low-Density Neutron Matter with Pionless NN Effective Field Theory  

E-Print Network (OSTI)

Thermal properties of low-density neutron matter are investigated by determinantal quantum Monte Carlo lattice calculations on 3+1 dimensional cubic lattices. Nuclear effective field theory (EFT) is applied using the pionless single- and two-parameter neutron-neutron interactions, determined from the $^1S_0$ scattering length and effective range. The determination of the interactions and the calculations of neutron matter are carried out consistently by applying EFT power counting rules. The thermodynamic limit is taken by the method of finite-size scaling, and the continuum limit is examined in the vanishing lattice filling limit. The $^1S_0$ pairing gap at $T \\approx 0$ is computed directly from the off-diagonal long-range order of the spin pair-pair correlation function, and is found to be approximately 30% smaller than BCS calculations with the conventional nucleon-nucleon potentials. The critical temperature $T_c$ of the normal-to-superfluid phase transition and the pairing temperature scale $T^\\ast$ are determined, and the temperature-density phase diagram is constructed. The physics of low-density neutron matter is clearly identified as being a BCS-Bose-Einstein condensation crossover.

T. Abe; R. Seki

2007-08-19T23:59:59.000Z

399

Three dimensional massive scalar field theory and the derivative expansion of the renormalization group  

E-Print Network (OSTI)

We show that non-perturbative fixed points of the exact renormalization group, their perturbations and corresponding massive field theories can all be determined directly in the continuum -- without using bare actions or any tuning procedure. As an example, we estimate the universal couplings of the non-perturbative three-dimensional one-component massive scalar field theory in the Ising model universality class, by using a derivative expansion (and no other approximation). These are compared to the recent results from other methods. At order derivative-squared approximation, the four-point coupling at zero momentum is better determined by other methods, but factoring this out appropriately, all our other results are in very close agreement with the most powerful of these methods. In addition we provide for the first time, estimates of the n-point couplings at zero momentum, with n=12,14, and the order momentum-squared parts with n=2 ... 10.

Tim R. Morris

1996-12-11T23:59:59.000Z

400

On p-Adic Sector of Open Scalar Strings and Zeta Field Theory  

Science Conference Proceedings (OSTI)

We consider construction of Lagrangians which may be suitable for description of p-adic sector of an open scalar string. Such Lagrangians have their origin in Lagrangian for a single p-adic string and they contain the Riemann zeta function with the d'Alembertian in its argument. However, investigation of the field theory with Riemann zeta function is interesting in itself as well. We present a brief review and some new results.

Dragovich, Branko [Institute of Physics, Pregrevica 118, Zemun, P.O. Box 57, 11001 Belgrade (Serbia)

2010-06-17T23:59:59.000Z

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


401

Some properties of the Cauchy-type integral for the Laplace vector fields theory  

SciTech Connect

We study the analog of the Cauchy-type integral for the Laplace vector fields theory in case of a piece-wise Liapunov surface of integration and we prove the Sokhotski-Plemelj theorem for it as well as the necessary and sufficient condition for the possibility to extend a given Hoelder function from such a surface up to a Laplace vector field. Formula for the square of the singular Cauchy-type integral is given. The proofs of all these facts are based on intimate relations between Laplace vector held and some versions of quaternionic analysis.

Schneider, Baruch [Department of Mathematics, Izmir University of Economics, 35330, Balcova, Izmir (Turkey); Shapiro, Michael [Departamento de Matematicas, Escuela Superior de Fisica y Mathematicas, 07300 Mexico, D.F. (Mexico)

2004-10-04T23:59:59.000Z

402

Field theory of massive and massless vector particles in the Duffin - Kemmer - Petiau formalism  

E-Print Network (OSTI)

Field theory of massive and massless vector particles is considered in the first-order formalism. The Hamiltonian form of equations is obtained after the exclusion of non-dynamical components. We obtain the canonical and symmetrical Belinfante energy-momentum tensors and their nonzero traces. We note that the dilatation symmetry is broken in the massive case but in the massless case the modified dilatation current is conserved. The canonical quantization is performed and the propagator of the massive fields is found in the Duffin - Kemmer - Petiau formalism.

S. I. Kruglov

2010-09-24T23:59:59.000Z

403

The Global Renormalization Group Trajectory in a Critical Supersymmetric Field Theory on the Lattice Z^3  

E-Print Network (OSTI)

We consider an Euclidean supersymmetric field theory in $Z^3$ given by a supersymmetric $\\Phi^4$ perturbation of an underlying massless Gaussian measure on scalar bosonic and Grassmann fields with covariance the Green's function of a (stable) L\\'evy random walk in $Z^3$. The Green's function depends on the L\\'evy-Khintchine parameter $\\alpha={3+\\epsilon\\over 2}$ with $00$ sufficiently small and initial parameters held in an appropriate domain the existence of a global renormalization group trajectory uniformly bounded on all renormalization group scales and therefore on lattices which become arbitrarily fine. At the same time we establish the existence of the critical (stable) manifold. The interactions are uniformly bounded away from zero on all scales and therefore we are constructing a non-Gaussian supersymmetric field theory on all scales. The interest of this theory comes from the easily established fact that the Green's function of a (weakly) self-avoiding L\\'evy walk in $Z^3$ is a second moment (two po...

Mitter, P K

2007-01-01T23:59:59.000Z

404

Equivariant spectral triples on the quantum SU(2) group, K-Theory 28  

E-Print Network (OSTI)

We characterize all equivariant odd spectral triples for the quantum SU(2) group acting on its L2-space and having a nontrivial Chern character. It is shown that the dimension of an equivariant spectral triple is at least three, and given any element of the K-homology group of SUq(2), there is an equivariant odd spectral triple of dimension 3 inducing that element. The method employed to get equivariant spectral triples in the quantum case is then used for classical SU(2), and we prove that for p < 4, there does not exist any equivariant spectral triple with nontrivial K-homology class and dimension p acting on the L2-space.

Partha Sarathi Chakraborty; Arupkumar Pal

2003-01-01T23:59:59.000Z

405

Quantum Theory of Transmission Line Resonator-Assisted Cooling of a Micromechanical Resonator  

E-Print Network (OSTI)

We propose a quantum description of the cooling of a micromechanical flexural oscillator by a one-dimensional transmission line resonator via a force that resembles cavity radiation pressure. The mechanical oscillator is capacitively coupled to the central conductor of the transmission line resonator. At the optimal point, the micromechanical oscillator can be cooled near to the ground state and the cooling can be measured by homodyne detection of the output microwave signal.

Li, Yong; Xue, Fei; Bruder, C

2008-01-01T23:59:59.000Z

406

Quantum Theory of Transmission Line Resonator-Assisted Cooling of a Micromechanical Resonator  

E-Print Network (OSTI)

We propose a quantum description of the cooling of a micromechanical flexural oscillator by a one-dimensional transmission line resonator via a force that resembles cavity radiation pressure. The mechanical oscillator is capacitively coupled to the central conductor of the transmission line resonator. At the optimal point, the micromechanical oscillator can be cooled close to the ground state, and the cooling can be measured by homodyne detection of the output microwave signal.

Yong Li; Ying-Dan Wang; Fei Xue; C. Bruder

2008-04-30T23:59:59.000Z

407

The confining N = 1 supersymmetric gauge theories: A review  

Science Conference Proceedings (OSTI)

The authors give a classification and overview of the confining N = 1 supersymmetric gauge theories. For simplicity they consider only theories based on simple gauge groups and no tree-level superpotential. Classification of these theories can be done according to whether or not there is a superpotential generated for the confined degrees of freedom. The theories with the superpotential include s-confining theories and also theories where the gauge fields participate in the confining spectrum, while theories with no superpotential include theories with a quantum deformed moduli space and theories with an affine moduli space.

Csaki, C. [Univ. of California, Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley National Lab., CA (United States). Physics Div.

1998-08-01T23:59:59.000Z

408

Nonradiating and minimum energy sources and their fields: Generalized source inversion theory and applications  

E-Print Network (OSTI)

AbstractA new general framework for characterizing scalar and electromagnetic (EM) nonradiating (NR) and minimum energy (ME) sources and their fields is developed that is of interest for both radiation and source reconstruction problems. NR sources are characterized in connection with the concept of reciprocity as nonreceptors. Localized ME sources are shown to be free fields truncated within the sources support. A new source analysis tool is developed that is based on the decomposition of a source and its field into their radiating and NR components. The individual radiating and reactive energy roles of the radiating and NR parts of a source are characterized. The general theory is illustrated with a time-harmonic EM example. Index TermsInverse problems.

Edwin A. Marengo; Richard W. Ziolkowski

2000-01-01T23:59:59.000Z

409

Hole mobility enhancement in In0.41 Ga0.59 Sb quantum-well field-effect transistors  

E-Print Network (OSTI)

The impact of ?110? uniaxial strain on the characteristics of p-channel In[subscript 0.41]Ga[subscript 0.59]Sb quantum-well field-effect transistors (QW-FETs) is studied through chip-bending experiments. Uniaxial strain ...

Xia, Ling

410

A UNIFIED PARTICLE DIFFUSION THEORY FOR CROSS-FIELD SCATTERING: SUBDIFFUSION, RECOVERY OF DIFFUSION, AND DIFFUSION IN THREE-DIMENSIONAL TURBULENCE  

Science Conference Proceedings (OSTI)

A new nonlinear theory for cosmic-ray scattering across the mean magnetic field is derived. This theory can be applied for arbitrary turbulence geometry. Previous theories such as the extended nonlinear guiding center theory are deduced as special limits. Furthermore, the new theory can explain subdiffusive transport for slab turbulence and the recovery of diffusion for slab/two-dimensional and three-dimensional turbulence. The nonlinear standard theory for field line wandering can be obtained as a special limit.

Shalchi, A., E-mail: andreasm4@yahoo.co [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)

2010-09-10T23:59:59.000Z

411

On the generalized eigenvalue method for energies and matrix elements in lattice field theory  

E-Print Network (OSTI)

We discuss the generalized eigenvalue problem for computing energies and matrix elements in lattice gauge theory, including effective theories such as HQET. It is analyzed how the extracted effective energies and matrix elements converge when the time separations are made large. This suggests a particularly efficient application of the method for which we can prove that corrections vanish asymptotically as $\\exp(-(E_{N+1}-E_n) t)$. The gap $E_{N+1}-E_n$ can be made large by increasing the number $N$ of interpolating fields in the correlation matrix. We also show how excited state matrix elements can be extracted such that contaminations from all other states disappear exponentially in time. As a demonstration we present numerical results for the extraction of ground state and excited B-meson masses and decay constants in static approximation and to order $1/m_b$ in HQET.

Benoit Blossier; Michele Della Morte; Georg von Hippel; Tereza Mendes; Rainer Sommer

2009-02-07T23:59:59.000Z

412

The Renormalization Group and Two Dimensional Multicritical Effective Scalar Field Theory  

E-Print Network (OSTI)

Direct verification of the existence of an infinite set of multicritical non-perturbative FPs (Fixed Points) for a single scalar field in two dimensions, is in practice well outside the capabilities of the present standard approximate non-perturbative methods. We apply a derivative expansion of the exact RG (Renormalization Group) equations in a form which allows the corresponding FP equations to appear as non-linear eigenvalue equations for the anomalous scaling dimension $\\eta$. At zeroth order, only continuum limits based on critical sine-Gordon models, are accessible. At second order in derivatives, we perform a general search over all $\\eta\\ge.02$, finding the expected first ten FPs, and {\\sl only} these. For each of these we verify the correct relevant qualitative behaviour, and compute critical exponents, and the dimensions of up to the first ten lowest dimension operators. Depending on the quantity, our lowest order approximate description agrees with CFT (Conformal Field Theory) with an accuracy between 0.2\\% and 33\\%; this requires however that certain irrelevant operators that are total derivatives in the CFT are associated with ones that are not total derivatives in the scalar field theory.

Tim R. Morris

1994-10-19T23:59:59.000Z

413

The Vertical Structure of the Wave Bottom Boundary Layer over a Sloping Bed: Theory and Field Measurements  

Science Conference Proceedings (OSTI)

Theoretical solutions for the wave bottom boundary layer (WBL) over a sloping bed are compared with field measurements in the nearshore zone. The WBL theory is constructed using both viscoelasticdiffusion and conventional eddy viscosity ...

Qingping Zou; Alex E. Hay

2003-07-01T23:59:59.000Z

414

Proton-Proton Fusion in Effective Field Theory to Fifth Order  

E-Print Network (OSTI)

The proton-proton fusion process p p->d e^+ nu_e is calculated at threshold to fifth order in pionless effective field theory. There are two unknown two-body currents contributing at the second and fourth orders. Combined with the previous results for neutrino-deuteron and antineutrino-deuteron scattering, computed to third order in the same approach, we conclude that a 10% measurement of reactor antineutrino-deuteron scattering measurement could constrain the p p->d e^+ nu_e rate to ~7% while a ~3% measurement of nu_e d-> e^- p p could constrain the pp rate to ~2%.

Butler, M; Butler, Malcolm; Chen, Jiunn-Wei

2001-01-01T23:59:59.000Z

415

Hyperon-nucleon interaction and baryonic contact terms in SU(3) chiral effective field theory  

E-Print Network (OSTI)

In this proceeding we summarize results for baryonic contact terms derived within SU(3) chiral effective field theory. The four-baryon contact terms, necessary for the description of the hyperon-nucleon interaction, include SU(3) symmetric and explicit chiral symmetry breaking terms. They also include four-baryon contact terms involving pseudoscalar mesons, which become important for three-body forces. Furthermore we derive the leading order six-baryon contact terms in the non-relativistic limit and study their contribution to the $\\Lambda NN$ three-body contact interaction. These results could play an important role in studies of hypernuclei or hyperons in nuclear matter.

Stefan Petschauer

2013-12-16T23:59:59.000Z

416

Proton-Proton Fusion in Effective Field Theory to Fifth Order  

E-Print Network (OSTI)

The proton-proton fusion process p p->d e^+ nu_e is calculated at threshold to fifth order in pionless effective field theory. There are two unknown two-body currents contributing at the second and fourth orders. Combined with the previous results for neutrino-deuteron and antineutrino-deuteron scattering, computed to third order in the same approach, we conclude that a 10% measurement of reactor antineutrino-deuteron scattering measurement could constrain the p p->d e^+ nu_e rate to ~7% while a ~3% measurement of nu_e d-> e^- p p could constrain the pp rate to ~2%.

Malcolm Butler; Jiunn-Wei Chen

2001-01-08T23:59:59.000Z

417

The Particle Adventure | Unsolved Mysteries | String theory  

NLE Websites -- All DOE Office Websites (Extended Search)

String theory String theory Modern physics has good theories for quantum mechanics, relativity, and gravity. But these theories do not quite work with each other. There are...

418

Quantum Gravity An introductory survey  

E-Print Network (OSTI)

Quantum Gravity An introductory survey Hermann Nicolai Max-Planck-Institut f¨ur Gravitationsphysik (Albert­Einstein­Institut, Potsdam) . ­ p.1/25 #12;Why Quantum Gravity? . ­ p.2/25 #12;Why Quantum Gravity theories: . ­ p.2/25 #12;Why Quantum Gravity? General Relativity and Quantum Theory: not only very

Rossak, Wilhelm R.

419

Generalization of the Activated Complex Theory of Reaction Rates. I. Quantum Mechanical Treatment  

DOE R&D Accomplishments (OSTI)

In its usual form activated complex theory assumes a quasi-equilibrium between reactants and activated complex, a separable reaction coordinate, a Cartesian reaction coordinate, and an absence of interaction of rotation with internal motion in the complex. In the present paper a rate expression is derived without introducing the Cartesian assumption. The expression bears a formal resemblance to the usual one and reduces to it when the added assumptions of the latter are introduced.

Marcus, R. A.

1964-00-00T23:59:59.000Z

420

$a-c$ test of holography vs quantum renormalization group  

E-Print Network (OSTI)

We show that a "constructive derivation" of the AdS/CFT correspondence based on the quantum local renormalization group in large N quantum field theories consistently provides the a-c holographic Weyl anomaly in d=4 at the curvature squared order in the bulk action. The consistency of the construction further predicts the form of the metric beta function.

Yu Nakayama

2014-01-21T23:59:59.000Z

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While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

The nucleon and Delta-resonance masses in relativistic chiral effective-field theory  

SciTech Connect

We study the chiral behavior of the nucleon and De-isobar masses within a manifestly covariant chiral effective-field theory, consistent with the analyticity principle. We compute the {pi} N and {pi}{Delta} one-loop contributions to the mass and field-normalization constant, and find that they can be described in terms of universal relativistic loop functions, multiplied by appropriate spin, isospin and coupling constants. We show that these relativistic one-loop corrections, when properly renormalized, obey the chiral power-counting and vanish in the chiral limit. The results including only the {pi} N-loop corrections compare favorably with the lattice QCD data for the pion-mass dependence of the nucleon and De masses, while inclusion of the {pi}/De loops tends to spoil this agreement.

V. Pascalutsa; M. Vanderhaeghen

2005-11-28T23:59:59.000Z

422

On the Velocity in the Effective Field Theory of Large Scale Structures  

E-Print Network (OSTI)

We compute the renormalized two-point functions of density, divergence and vorticity of the velocity in the Effective Field Theory of Large Scale Structures. We show that the mass-weighted velocity, as opposed to the volume-weighted velocity, is the natural variable to use. We then prove that, Because of momentum and mass conservation, the corrections from short scales to the large-scale power spectra of density, divergence and vorticity must start at order $k^{4}$. For the vorticity this constitutes the leading term. Exact (approximated) self-similarity of an Einstein-de Sitter ($\\Lambda$CDM) background fixes the time dependence so that the vorticity power spectrum at leading order is uniquely determined, up to a normalization, by the symmetries of the problem. Focusing on density and velocity divergence, we show that the current formulation of the theory does not have enough counterterms to cancel all divergences. At the lowest order, the missing terms are a new stochastic noise and a heat conduction term in the continuity equation. For an Einstein de Sitter universe, we show that all three renormalized cross- and auto-correlation functions have the same structure but different numerical coefficients, which we compute. Using momentum instead of velocity, one can re-absorb the new terms and work with an uncorrected continuity equation but at the cost of having uncancelled IR divergences in equal-time correlators and a more complicated perturbation theory.

Lorenzo Mercolli; Enrico Pajer

2013-07-11T23:59:59.000Z

423

Quantum Cosmology  

E-Print Network (OSTI)

We give an introduction into quantum cosmology with emphasis on its conceptual parts. After a general motivation we review the formalism of canonical quantum gravity on which discussions of quantum cosmology are usually based. We then present the minisuperspace Wheeler--DeWitt equation and elaborate on the problem of time, the imposition of boundary conditions, the semiclassical approximation, the origin of irreversibility, and singularity avoidance. Restriction is made to quantum geometrodynamics; loop quantum gravity and string theory are discussed in other contributions to this volume.

Claus Kiefer; Barbara Sandhoefer

2008-04-04T23:59:59.000Z

424

Theory of magnetization transport in a spatially varying magnetic field derived from entropic considerations  

E-Print Network (OSTI)

A theory of magnetization transport of a single spin-species in a spatially varying magnetic field is derived from entropic considerations. The theory describes thermodynamic transport in the language of differential geometry. Both magnetization diffusion and separation are predicted from a sample geometry, a magnetic field geometry, an entropy density function, and a single space-time scale. It is expressed first and most generally as coupled nonlinear partial differential equations, which are valid for the regime of high dipole-energy and magnetization. Second, the nonlinear model is explored in the limit of low dipole-energy (semi-linear), from which is derived a physical parameter characterizing separative magnetization transport (SMT). It is shown that the necessary and sufficient condition for SMT to occur is that the SMT parameter is spatially inhomogeneous. Third, the high spin-temperature (linear) limit is derived, and is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield. Differences among the three models are illustrated by numerical solution. A family of analytic, steady-state solutions to the nonlinear transport equation is derived and shown to be the spin-temperature analog of the Langevin paramagnetic equation and Curie's law. A steady-state solution for the magnetization is shown to be equivalent to the widely applied separation equation of Fenske. Moreover, we show that the SMT parameter is functionally related to the relative volatility parameter of Fenske.

Rico A. R. Picone; Joseph L. Garbini; John A. Sidles

2013-10-28T23:59:59.000Z

425

Electric-magnetic duality and deformations of three-dimensional conformal field theories  

SciTech Connect

SL(2,Z) duality transformations in asymptotically AdS{sub 4}xS{sup 7} act nontrivially on the three-dimensional superconformal field theory of coincident M2-branes on the boundary. We show how S-duality acts away from the IR fixed point. We develop a systematic method to holographically obtain the deformations of the boundary CFT and show how electric-magnetic duality relates different deformations. We analyze in detail marginal deformations and deformations by dimension 4 operators. In the case of massive deformations, the renormalization group flow relates S-dual CFT's. Correlation functions in the CFT are computed by varying magnetic bulk sources, whereas correlation functions in the dual CFT are computed by electric bulk sources. Under massive deformations, the boundary effective action is generically minimized by massive self-dual configurations of the U(1) gauge field. We show that a self-dual choice of boundary conditions exists, and it corresponds to the self-dual topologically massive gauge theory in 2+1 dimensions. Thus, self-duality in three dimensions can be understood as a consequence of electric-magnetic invariance in the bulk of AdS{sub 4}.

Haro, Sebastian de [Department of Mathematics, King's College, London WC2R 2LS (United Kingdom); Gao Peng [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396 (United States)

2007-11-15T23:59:59.000Z

426

Augmented Superfield Approach To Exact Nilpotent Symmetries For Matter Fields In Non-Abelian Theory  

E-Print Network (OSTI)

We derive the nilpotent (anti-)BRST symmetry transformations for the Dirac (matter) fields of an interacting four (3+1)-dimensional 1-form non-Abelian gauge theory by applying the theoretical arsenal of augmented superfield formalism where (i) the horizontality condition, and (ii) the equality of a gauge invariant quantity, on the six (4, 2)-dimensional supermanifold, are exploited together. The above supermanifold is parameterized by four bosonic spacetime coordinates x^\\mu (with \\mu = 0,1,2,3) and a couple of Grassmannian variables \\theta and \\bar{\\theta}. The on-shell nilpotent BRST symmetry transformations for all the fields of the theory are derived by considering the chiral superfields on the five (4, 1)-dimensional super sub-manifold and the off-shell nilpotent symmetry transformations emerge from the consideration of the general superfields on the full six (4, 2)-dimensional supermanifold. Geometrical interpretations for all the above nilpotent symmetry transformations are also discussed in the framework of augmented superfield formalism.

R. P. Malik; Bhabani Prasad Mandal

2005-12-29T23:59:59.000Z

427

Critical behavior of the aperiodic quantum Ising chain in a transverse magnetic field  

SciTech Connect

The authors consider the quantum spin-1/2 Ising chain in an uniform transverse magnetic field, with an aperiodic sequence of ferromagnetic exchange couplings. This system is a limiting anisotropic case of the classical two-dimensional Ising model with an arbitrary layered modulation. Its formal solution via a Jordan-Winger transformation enables one to obtain a detailed description of the influence of the aperiodic modulation on the singularity of the ground-state energy at the critical point. The key concept is that of the fluctuation of the sums of any number of consecutive couplings at the critical point. When the fluctuation is bounded, the model belongs to the Onsager universality class of the uniform chain. The amplitude of the logarithmic divergence in the specific heat is proportional to the velocity of the fermionic excitations, for which the authors give explicit expressions in most cases of interest, including the periodic and quasiperiodic cases, the Thue-Morse chain, and the random dimer model. When the couplings exhibit an unbounded fluctuation, the critical singularity is shown to be generically similar to that of the critical point, and an exponentially small singular part, for which the authors give a quantitative estimate. In the marginal case of a logarithmically divergent fluctuation, e.g., for the period-doubling sequence or the circle sequence or the circle sequence, there is a negative specific heat exponent [alpha], which varies continuously with the strength of the aperiodic modulation. 55 refs., 2 figs.

Luck, J.M. (Centre D'Etudes de Saclay, Gif-sur-Yvette (France))

1993-08-01T23:59:59.000Z

428

Unified Field Theory From Enlarged Transformation Group. The Covariant Derivative for Conservative Coordinate Transformations and Local Frame Transformations  

E-Print Network (OSTI)

Pandres has developed a theory in which the geometrical structure of a real four-dimensional space-time is expressed by a real orthonormal tetrad, and the group of diffeomorphisms is replaced by a larger group called the conservation group. This paper extends the geometrical foundation for Pandres' theory by developing an appropriate covariant derivative which is covariant under all local Lorentz (frame) transformations, including complex Lorentz transformations, as well as conservative transformations. After defining this extended covariant derivative, an appropriate Lagrangian and its resulting field equations are derived. As in Pandres' theory, these field equations result in a stress-energy tensor that has terms which may automatically represent the electroweak field. Finally, the theory is extended to include 2-spinors and 4-spinors.

Edward Lee Green

2009-07-22T23:59:59.000Z

429

Chaos and Nonlinear Dynamics in a Quantum Artificial Economy  

E-Print Network (OSTI)

Chaos and nonlinear economic dynamics are addressed for a quantum coupled map lattice model of an artificial economy, with quantized supply and demand equilibrium conditions. The measure theoretic properties and the patterns that emerge in both the economic business volume dynamics' diagrams as well as in the quantum mean field averages are addressed and conclusions are drawn in regards to the application of quantum chaos theory to address signatures of chaotic dynamics in relevant discrete economic state variables.

Gonalves, Carlos Pedro

2012-01-01T23:59:59.000Z

430

Chaos and Nonlinear Dynamics in a Quantum Artificial Economy  

E-Print Network (OSTI)

Chaos and nonlinear economic dynamics are addressed for a quantum coupled map lattice model of an artificial economy, with quantized supply and demand equilibrium conditions. The measure theoretic properties and the patterns that emerge in both the economic business volume dynamics' diagrams as well as in the quantum mean field averages are addressed and conclusions are drawn in regards to the application of quantum chaos theory to address signatures of chaotic dynamics in relevant discrete economic state variables.

Carlos Pedro Gonalves

2012-02-29T23:59:59.000Z

431

Quantum Theory at Planck Scale, Limiting Values, Deformed Gravity and Dark Energy Problem  

E-Print Network (OSTI)

Within a theory of the existing fundamental length on the order of Planck's a high-energy deformation of the General Relativity for the space with horizon has been constructed. On this basis, Markov's work of the early eighties of the last century has been given a new interpretation to show that the heuristic model considered by him may be placed on a fundamental footing. The obtained results have been applied to solving of the dark energy problem, making it possible to frame the following hypothesis: a dynamic cosmological term is a measure of deviation from a thermodynamic identity (the first law of thermodynamics) of the high-energy (Planck's) deformation of Einstein equations for horizon spaces in their thermodynamic interpretation.

A. E. Shalyt-Margolin

2011-02-24T23:59:59.000Z

432

Quantum information in a nutshell () Quantum mechanics + information science  

E-Print Network (OSTI)

Quantum information in a nutshell (?²¤¶) Quantum mechanics + information science = quantum information science = quantum information transfer + quantum algorithm (software) + quantum computer (hardware) + quantum simulation +... = a field rapidly growing in the last 10 years ®v½d¤j¾?ª«²z¨t ±i©ú-õ #12;Brief

Chang, Ming-Che

433

Quantum Weak Measurements and Cosmology  

E-Print Network (OSTI)

The indeterminism of quantum mechanics generally permits the independent specification of both an initial and a final condition on the state. Quantum pre-and-post-selection of states opens up a new, experimentally testable, sector of quantum mechanics, when combined with statistical averages of identical weak measurements. In this paper I apply the theory of weak quantum measurements combined with pre-and-post-selection to cosmology. Here, pre-selection means specifying the wave function of the universe or, in a popular semi-classical approximation, the initial quantum state of a subset of quantum fields propagating in a classical back-ground spacetime. The novel feature is post-selection: the additional specification of a condition on the quantum state in the far future. I discuss "natural" final conditions, and show how they may lead to potentially large and observable effects at the present cosmological epoch. I also discuss how pre-and-post-selected quantum contrast to the expectation value of the stress-energy-momentum tensor, resolving a vigorous debate from the 1970's. The paper thus provides a framework for computing large-scale cosmological effects arising from this new sector of quantum mechanics. A simple experimental test is proposed.

Paul Davies

2013-09-03T23:59:59.000Z

434

Quantum-fluid-dynamics approach for strong-field processes: Application to the study of multiphoton ionization and high-order harmonic generation of He and Ne atoms  

E-Print Network (OSTI)

Wigner cor- relation energy functionals are used. QUANTUM-FLUID-DYNAMICS APPROACH FOR STRONGQuantum-fluid-dynamics approach for strong-field processes: Application to the study of multiphoton; published 18 March 2002 We explore the feasibility of extending the quantum-fluid dynamics QFD approach

Chu, Shih-I

435

Quantum Geometry of the Dynamical Space-time  

E-Print Network (OSTI)

Quantum theory of field (extended) objects without a priori space-time geometry has been represented. Intrinsic coordinates in the tangent fibre bundle over complex projective Hilbert state space $CP(N-1)$ are used instead of space-time coordinates. The fate of quantum system modeled by the generalized coherent states is rooted in this manifold. Dynamical (state-dependent) space-time arises only at the stage of the quantum "yes/no" measurement. The quantum measurement of the gauge ``field shell'' of the generalized coherent state is described in terms of the affine parallel transport of the local dynamical variables in $CP(N-1)$.

Peter Leifer

2006-11-20T23:59:59.000Z

436

On the classical solution for the double-brane background in open string field theory  

E-Print Network (OSTI)

Murata and Schnabl recently proposed solutions for the multiple-brane backgrounds in Witten's open bosonic string field theory. The solutions contain some singularities, and in one particular regularization, the double-brane solution reproduces the desired energy and the Ellwood invariant, which is conjectured to represent coupling to a closed string. However, it turned out that the equation of motion is slightly violated. In this paper, we propose another regularization method for the double-brane solution. The regularized solution is realized as a superposition of the wedge states with operator insertions. It respects the equation of motion both contracted with the solution itself and with the states in the Fock space. It reproduces the desired double-brane tension, while the expected Ellwood invariant is not obtained.

Masuda, Toru

2012-01-01T23:59:59.000Z

437

Solar neutrino processes in the relativistic field theory model of the deuteron, nuclth/9811012  

E-Print Network (OSTI)

The generalized version of the relativistic field theory model of the deuteron (RFMD) is applied to the description of processes of astrophysical interest and lowenergy elastic NN scattering. The value of the astrophysical factor Spp(0) = 5.52 10?25MeV b for the solar proton burning p + p ? D + e + + ?e is found to be enhanced by a factor of 1.42 with respect to the classical value S ? pp (0) = 3.89 10?25 MeV b obtained by Kamionkowski and Bahcall in the potential model approach (PMA). The astrophysical aspects of this enhancement are discussed. The cross sections for the disintegration of the deuteron by (anti)neutrinos ?e + D ?

A. N. Ivanov; H. Oberhummer; N. I. Troitskaya; M. Faber

1998-01-01T23:59:59.000Z

438

Quantum limit in continuous quantum measurement  

E-Print Network (OSTI)

The quantum noise is calculated based on the description of imprecise measurement theory, which is used to analyse the general detector's quantum limit in continuous quantum measurement. Different from the traditional description of the linear-response theory, we don't introduce the hypotheses on the properties of the susceptibilities of the detector, and first show a rigorous result: The minimum noise added by the detector in quantum measurement is precisely equal to the zero-point noise. We also discuss the statistic characters of the back-action force in quantum measurement and show how to reach the quantum limit.

Shao, ChengGang

2012-01-01T23:59:59.000Z

439

PION CONDENSATION IN A FIELD THEORY CONSISTENT WITH BULK PROPERTIES OF NUCLEAR MATTER  

E-Print Network (OSTI)

theory is constrained to reproduce the known bulk properties of nuclear matter, namely its saturation energy,

Banerjee, B.

2013-01-01T23:59:59.000Z

440

Non-Gaussian statistics, classical field theory, and realizable Langevin models  

SciTech Connect

The direct-interaction approximation (DIA) to the fourth-order statistic Z {approximately}{l_angle}{lambda}{psi}{sup 2}){sup 2}{r_angle}, where {lambda} is a specified operator and {psi} is a random field, is discussed from several points of view distinct from that of Chen et al. [Phys. Fluids A 1, 1844 (1989)]. It is shown that the formula for Z{sub DIA} already appeared in the seminal work of Martin, Siggia, and Rose (Phys. Rev. A 8, 423 (1973)] on the functional approach to classical statistical dynamics. It does not follow from the original generalized Langevin equation (GLE) of Leith [J. Atmos. Sd. 28, 145 (1971)] and Kraichnan [J. Fluid Mech. 41, 189 (1970)] (frequently described as an amplitude representation for the DIA), in which the random forcing is realized by a particular superposition of products of random variables. The relationship of that GLE to renormalized field theories with non-Gaussian corrections (``spurious vertices``) is described. It is shown how to derive an improved representation, that realizes cumulants through O({psi}{sup 4}), by adding to the GLE a particular non-Gaussian correction. A Markovian approximation Z{sub DIA}{sup M} to Z{sub DIA} is derived. Both Z{sub DIA} and Z{sub DIA}{sup M} incorrectly predict a Gaussian kurtosis for the steady state of a solvable three-mode example.

Krommes, J.A.

1995-11-01T23:59:59.000Z

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


441

Coagulation kinetics beyond mean field theory using an optimised Poisson representation  

E-Print Network (OSTI)

Binary particle coagulation can be modelled as the repeated random process of the combination of two particles to form a third. The kinetics can be represented by population rate equations based on a mean field assumption, according to which the rate of aggregation is taken to be proportional to the product of the mean populations of the two participants. This can be a poor approximation when the mean populations are small. However, using the Poisson representation it is possible to derive a set of rate equations that go beyond mean field theory, describing pseudo-populations that are continuous, noisy and complex, but where averaging over the noise and initial conditions gives the mean of the physical population. Such an approach is explored for the simple case of a size-independent rate of coagulation between particles. Analytical results are compared with numerical computations and with results derived by other means. In the numerical work we encounter instabilities that can be eliminated using a suitable `gauge' transformation of the problem [P. D. Drummond, Eur. Phys. J. B38, 617 (2004)] which we show to be equivalent to the application of the Cameron-Martin-Girsanov formula describing a shift in a probability measure. The cost of such a procedure is to introduce additional statistical noise into the numerical results, but we identify an optimised gauge transformation where this difficulty is minimal for the main properties of interest. For more complicated systems, such an approach is likely to be computationally cheaper than Monte Carlo simulation.

James Burnett; Ian J. Ford

2012-12-10T23:59:59.000Z

442

Quantum Operations and Measurement  

E-Print Network (OSTI)

Quantum Operations and Measurement M.P Seevinck E-mail: M.P.Seevinck@phys.uu.nl Utrecht field in quantum physics ­ or perhaps better, a new way of doing quantum physics ­ . . . Surprisingly of these developments to the conceptual problems of quantum mechanics. In our view, the new work on quantum information

Seevinck, Michiel

443

Quantum Nanomechanics Pritiraj Mohanty  

E-Print Network (OSTI)

Quantum Nanomechanics Pritiraj Mohanty Abstract Quantum Nanomechanics is the emerging field which pertains to the me- chanical behavior of nanoscale systems in the quantum domain. Unlike the conven- tional studies of vibration of molecules and phonons in solids, quantum nanome- chanics is defined as the quantum

444

Influence of Internal Fields on the Electronic Structure in Self-Assembled InAs/GaAs Quantum Dots  

E-Print Network (OSTI)

Built-in electrostatic fields in Zincblende quantum dots originate mainly from - (1) the fundamental crystal atomicity and the interfaces between two dissimilar materials, (2) the strain relaxation, and (3) the piezoelectric polarization. In this paper, using the atomistic NEMO 3-D simulator, we study the origin and nature of the internal fields in InAs/GaAs quantum dots with three different geometries, namely, box, dome, and pyramid. We then calculate and delineate the impact of the internal fields in the one-particle electronic states in terms of shift in the conduction band energy states, anisotropy and non-degeneracy in the P level, and formation of mixed excited bound states. Models and approaches used in this study are as follow: (1) Valence force field (VFF) with strain-dependent Keating potentials for atomistic strain relaxation; (2) 20-band nearest-neighbor sp3d5s* tight-binding model for the calculation of single-particle energy states; and (3) For piezoelectricity, for the first time within the fra...

Islam, Sharnali; Ahmed, Shaikh

2010-01-01T23:59:59.000Z

445

Self-force on extreme mass ratio inspirals via curved spacetime effective field theory  

E-Print Network (OSTI)

In this series we construct an effective field theory (EFT) in curved spacetime to study gravitational radiation and backreaction effects. We begin in this paper with a derivation of the self-force on a compact object moving in the background spacetime of a supermassive black hole. The EFT approach utilizes the disparity between two length scales, which in this problem are the size of the compact object and the radius of curvature of the background spacetime, to treat the orbital dynamics of the compact object, described as an effective point particle, separately from its tidal deformations. Ultraviolet divergences are regularized using Hadamard's {\\it partie finie} to isolate the non-local finite part from the quasi-local divergent part. The latter is constructed from a momentum space representation for the graviton retarded propagator and is evaluated using dimensional regularization in which only logarithmic divergences are relevant for renormalizing the parameters of the theory. As a first important application of this framework we explicitly derive the first order self-force given by Mino, Sasaki, Tanaka, Quinn and Wald. Going beyond the point particle approximation, to account for the finite size of the object, we demonstrate that for extreme mass ratio inspirals the motion of a compact object is affected by tidally induced moments at $O(\\epsilon^4)$, in the form of an Effacement Principle. The relatively large radius-to-mass ratio of a white dwarf star allows for these effects to be enhanced until the white dwarf becomes tidally disrupted, a potentially $O(\\epsilon^2)$ process, or plunges into the supermassive black hole. This work provides a new foundation for further exploration of higher order self force corrections, gravitational radiation and spinning compact objects.

Chad R. Galley; B. L. Hu

2008-01-07T23:59:59.000Z

446

The dynamics of quantum criticality: Quantum Monte Carlo and holography  

E-Print Network (OSTI)

Understanding the real time dynamics of systems near quantum critical points at non-zero temperatures constitutes an important yet challenging problem, especially in two spatial dimensions where interactions are strong. We present detailed quantum Monte Carlo results for two separate realizations of the superfluid-insulator transition of bosons on a lattice: their low-frequency conductivities are found to have the same universal dependence on imaginary frequency and temperature. We then use the structure of the real time dynamics of conformal field theories described by the holographic gauge/gravity duality to make progress on the difficult problem of analytically continuing the Monte Carlo data to real time. Our method yields quantitative and experimentally testable results on the frequency-dependent conductivity at the quantum critical point, and on the spectrum of quasinormal modes in the vicinity of the superfluid-insulator quantum phase transition. Extensions to other observables and universality classes are discussed.

William Witczak-Krempa; Erik Sorensen; Subir Sachdev

2013-09-11T23:59:59.000Z

447

Quantum state discrimination with bosonic channels and Gaussian states  

E-Print Network (OSTI)

Discriminating between quantum states is an indispensable part of quantum information theory. This thesis investigates state discrimination of continuous quantum variables, focusing on bosonic communication channels and ...

Tan, Si Hui, Ph. D. Massachusetts Institute of Technology

2010-01-01T23:59:59.000Z

448

About Spontaneous Symmetry Breaking in the Field Theory with Fundamental Mass  

E-Print Network (OSTI)

The simple examples of spontaneous breaking of various symmetries for the scalar theory with fundamental mass have been considered. Higgs generalizations on "fundamental mass" were introduced into the theory on a basis of the five-dimensional de Sitter space.

Umida Khodjaeva

2006-02-28T23:59:59.000Z

449

Relativistic Quantum Communication  

E-Print Network (OSTI)

In this Ph.D. thesis, I investigate the communication abilities of non-inertial observers and the precision to which they can measure parametrized states. I introduce relativistic quantum field theory with field quantisation, and the definition and transformations of mode functions in Minkowski, Schwarzschild and Rindler spaces. I introduce information theory by discussing the nature of information, defining the entropic information measures, and highlighting the differences between classical and quantum information. I review the field of relativistic quantum information. We investigate the communication abilities of an inertial observer to a relativistic observer hovering above a Schwarzschild black hole, using the Rindler approximation. We compare both classical communication and quantum entanglement generation of the state merging protocol, for both the single and dual rail encodings. We find that while classical communication remains finite right up to the horizon, the quantum entanglement generation tends to zero. We investigate the observers' abilities to precisely measure the parameter of a state that is communicated between Alice and Rob. This parameter was encoded to either the amplitudes of a single excitation state or the phase of a NOON state. With NOON states the dual rail encoding provided greater precision, which is different to the results for the other situations. The precision was maximum for a particular number of excitations in the NOON state. We calculated the bipartite communication for Alice-Rob and Alice-AntiRob beyond the single mode approximation. Rob and AntiRob are causally disconnected counter-accelerating observers. We found that Alice must choose in advance with whom, Rob or AntiRob she wants to create entanglement using a particular setup. She could communicate classically to both.

Dominic Hosler

2013-06-20T23:59:59.000Z

450

Theories without AB effect misrepresent the dynamics of the electromagnetic field  

SciTech Connect

A summary of arguments as to why the Aharonou-Bohm effect (AB) cannot be removed from quantum mechanics without spoiling the conservation and quantization of angular momentum. 8 refs. (WRJ)

Peshkin, M.

1985-01-01T23:59:59.000Z

451

On the Energy-Momentum Tensor of the Scalar Field in Scalar--Tensor Theories of Gravity  

E-Print Network (OSTI)

We study the dynamical description of gravity, the appropriate definition of the scalar field energy-momentum tensor, and the interrelation between them in scalar-tensor theories of gravity. We show that the quantity which one would naively identify as the energy-momentum tensor of the scalar field is not appropriate because it is spoiled by a part of the dynamical description of gravity. A new connection can be defined in terms of which the full dynamical description of gravity is explicit, and the correct scalar field energy-momentum tensor can be immediately identified. Certain inequalities must be imposed on the two free functions (the coupling function and the potential) that define a particular scalar-tensor theory, to ensure that the scalar field energy density never becomes negative. The correct dynamical description leads naturally to the Einstein frame formulation of scalar-tensor gravity which is also studied in detail.

David I. Santiago; Alexander S. Silbergleit

1999-04-02T23:59:59.000Z

452

Energy variational analysis of ions in water and channels: Field theory for primitive models of complex ionic fluids  

E-Print Network (OSTI)

Energy variational analysis of ions in water and channels: Field theory for primitive models EnVarA energy variational analysis that combines Hamilton's least action and Rayleigh's dissipation, and ion channels. Flows are driven by a combination of electrical and chemical potentials that depend

Liu, Chun

453

Computer science is the study of design, theory, and application of computers. It is a continuously evolving field based on  

E-Print Network (OSTI)

Computer science is the study of design, theory, and application of computers. It is a continuously evolving field based on electronics, linguistics, logic, mathematics, and systems engineering. The computer science program emphasizes the development of software and the use of computers focusing around

Hemmers, Oliver

454

Conformal field theory at central charge c=0: a measure of the indecomposability (b) parameters  

E-Print Network (OSTI)

A good understanding of conformal field theory (CFT) at c=0 is vital to the physics of disordered systems, as well as geometrical problems such as polymers and percolation. Steady progress has shown that these CFTs should be logarithmic, with indecomposable operator product expansions, and indecomposable representations of the Virasoro algebra. In one of the earliest papers on the subject, V. Gurarie introduced a single parameter b to quantify this indecomposability in terms of the logarithmic partner t of the stress energy tensor T. He and A. Ludwig conjectured further that b=-5/8 for polymers and b=5/6 for percolation. While a lot of physics may be hidden behind this parameter - which has also given rise to a lot of discussions - it had remained very elusive up to now, due to the lack of available methods to measure it experimentally or numerically, in contrast say with the central charge. We show in this paper how to overcome the many difficulties in trying to measure b. This requires control of a lattice scalar product, lattice Jordan cells, together with a precise construction of the state L_{-2}|0>. The final result is that b=5/6 for polymers. For percolation, we find that b=-5/8 within an XXZ or supersymmetric representation. In the geometrical representation, we do not find a Jordan cell for L_0 at level two (finite-size Hamiltonian and transfer matrices are fully diagonalizable), so there is no b in this case.

Jerome Dubail; Jesper Lykke Jacobsen; Hubert Saleur

2010-01-07T23:59:59.000Z