Lincoln, Don
2016-07-12
The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilabâs Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.
Calculations in Quantum Chromodynamics
Photiadis, D.M.
1985-01-01
The author analyzes two problems which extend the predictive ability of Quantum Chromodynamics. He studies composite operators in lattice gauge theory that reduce to operators of the form anti psi gamma DDDD ... psi in the continuum limit; such operators arise in perturbative analyses of quantum chromodynamics. Using these results and the data of a numerical simulation one could normalize exclusive processes and predict moments of deep inelastic scattering structure functions. To initiate the program the author constructs and renormalizes lattice operators to the one-loop level. He is encouraged that the hadronic matrix elements of the simpler operators are within reach of numerical simulations. The author also calculates a corrected photon spectrum in the endpoint region, z ..-->.. 1, for direct photon decay of the upsilon by summing the leading logarithms of (1-z) to all orders in perturbation theory. This effect causes the cross section to level out at approx. = = .8, removing the sharp peak in the tree level prediction, but does not cause the cross section to turn over.
Calculations in Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Photiadis, Douglas Marc
I analyze two problems which extend the predictive ability of Quantum Chromodynamics. I study composite operators in lattice gauge theory that reduce to operators of the form (')(psi) (GAMMA) DDDD . . . (psi) in the continuum limit; such operators arise in perturbative analyses of quantum chromodynamics. Using our results and the data of a numerical simulation one could normalize exclusive processes and predict moments of deep inelastic scattering structure functions. To initiate the program we construct and renormalize lattice operators to the one-loop level. We are encouraged that the hadronic matrix elements of the simpler operators are within reach of numerical simulations. I also calculate a corrected photon spectrum in the endpoint region, z (--->) 1, for direct photon decay of the upsilon by summing the leading logarithms of (1 -z) to all orders in perturbation theory. This effect causes the cross section to level out at (DBLTURN)z = .8, removing the sharp peak in the tree level prediction, but does not cause the cross section to turn over.
Quantum chromodynamics with advanced computing
Kronfeld, Andreas S.; /Fermilab
2008-07-01
We survey results in lattice quantum chromodynamics from groups in the USQCD Collaboration. The main focus is on physics, but many aspects of the discussion are aimed at an audience of computational physicists.
Experimental tests of quantum chromodynamics
Dorfan, J.
1987-04-01
Experimental tests of quantum chromodynamics are discussed in the e/sup +/e/sup -/ continuum, in pp and anti p p collisions, in measurements of ..cap alpha../sub s/ from UPSILON decays, in deep inelastic lepton scattering, and in the measurement of the photon structure function. A large body of data relating to the testing of quantum chromodynamics is reviewed, showing qualitative agreement between the data from a wide range of processes and QCD. 66 refs., 79 figs. (LEW)
Quantum chromodynamics in background fields
NASA Astrophysics Data System (ADS)
Huang, Tao; Huang, Zheng
1989-02-01
We try to build a framework for quantum chromodynamics in background fields. The nonvanishing vacuum condensates are described by the classical fields, while the corresponding quantum fields are quantized in the Furry representation and the physical states are defined in the physical QCD vacuum. The complete quark and gluon propagators are discussed in this framework and running condensate parameters are introduced by the renormalization requirement. A modified Callan-Symanzik equation is derived by taking account of the nonperturbative corrections.
Nonperturbative β-FUNCTION in Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Sissakian, A. N.; Solovtsov, I. L.; Solovtsova, O. P.
We propose a method by which it is possible to go beyond the scope of quantum chromodynamics perturbation theory. By using a new small parameter we formulate a systematic nonperturbative expansion and derive a renormalization β-function in quantum chromodynamics.
Double logarithmic asymptotic behavior in quantum chromodynamics
Kirschner, R.
1981-08-01
The double logarithmic contributions to the quark-(anti)quark scattering and annihilation amplitudes are summed to all orders in quantum chromodynamics. The results are a generalization of the calculations of Gorshkov et al. in the case of quantum electrodynamics.
Quantum electrodynamics in finite volume and nonrelativistic effective field theories
NASA Astrophysics Data System (ADS)
Fodor, Z.; Hoelbling, C.; Katz, S. D.; Lellouch, L.; Portelli, A.; Szabo, K. K.; Toth, B. C.
2016-04-01
Electromagnetic effects are increasingly being accounted for in lattice quantum chromodynamics computations. Because of their long-range nature, they lead to large finite-size effects over which it is important to gain analytical control. Nonrelativistic effective field theories provide an efficient tool to describe these effects. Here we argue that some care has to be taken when applying these methods to quantum electrodynamics in a finite volume.
Quantum chromodynamics and deep-inelastic scattering
Buras, A.J.
1980-08-01
Moments of deep-inelastic structure functions, parton distributions and parton fragmentation functions are discussed in the context of Quantum Chromodynamics with particular emphasis put on higher order corrections. A brief discussion of higher twist contributions is also given.
Synthesis of quantum chromodynamics and nuclear physics
Brodsky, S.J.; Lepage, G.P.
1980-08-01
The asymptotic freedom behavior of quantum chromodynamics allows the rigorous calculation of hadronic and nuclear amplitudes at short distances by perturbative methods. The implications of QCD for large-momentum-transfer nuclear form factors and scattering processes, as well as for the structure of nuclear wave functions and nuclear interactions at short distances, are discussed. The necessity for color-polarized internal nuclear states is also discussed. 6 figures.
Exclusive Processes in Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Brodsky, Stanley J.; Peter Lepage, G.
The following sections are included: * INTRODUCTION * NONRELATIVISTIC FORM FACTORS FOR HEAVY-QUARK MESONS * HADRONIC WAVEFUNCTIONS * DEFINITIONS * LIGHT-CONE BOUND-STATE EQUATIONS * GENERAL PROPERTIES OF LIGHT-CONE WAVEFUNCTIONS * RENORMALIZATION * CALCULATING * A PERTURBATIVE ANALYSIS * FACTORIZATION—LEADING ORDER ANALYSIS * THE QUARK DISTRIBUTION AMPLITUDE * DETERMINATION OF DISTRIBUTION AMPLITUDES * HIGHER ORDER ANALYSIS * COMPLICATIONS * How LARGE IS ASYMPTOTIC Q? * APPLICATIONS OF QCD TO THE PHENOMENOLOGY OF EXCLUSIVE REACTIONS * GENERAL FEATURES OF EXCLUSIVE PROCESSES IN QCD * ELECTROMAGNETIC FORM FACTORS * COMPARISON OF QCD SCALING WITH EXPERIMENT * EXCLUSIVE ANTI-PROTON PROTON ANNIHILATION PROCESSES * ADDITIONAL TESTS OF GLUON SPIN IN EXCLUSIVE PROCESSES * HADRONIC WAVEFUNCTION PHENOMENOLOGY * CALCULATING TH * THE PRE-QCD DEVELOPMENT OF EXCLUSIVE REACTIONS * EXCLUSIVE e+ e- ANNIHILATION PROCESSES * J/ψ DECAY TO HADRON PAIRS * THE π-ρ PUZZLE * FORM FACTOR ZEROS IN QCD * EXCLUSIVE γγ REACTIONS * QCD PROCESSES IN NUCLEI * EXCLUSIVE NUCLEAR REACTIONS - REDUCED AMPLITUDES * COLOR TRANSPARENCY * SPIN CORRELATIONS IN PROTON-PROTON SCATTERING * CONCLUSIONS * APPENDIX I BARYON FORM FACTORS AND EVOLUTION EQUATIONS * APPENDIX II LIGHT CONE QUANTIZATION AND PERTURBATION THEORY * APPENDIX III A NONPERTURBATIVE ANALYSIS OF EXCLUSIVE REACTIONS-DISCRETIZED LIGHT-CONE QUANTIZATION * ACKNOWLEDGEMENTS * REFERENCES
Lamb Shift in Nonrelativistic Quantum Electrodynamics.
ERIC Educational Resources Information Center
Grotch, Howard
1981-01-01
The bound electron self-energy or Lamb shift is calculated in nonrelativistic quantum electrodynamics. Retardation is retained and also an interaction previously dropped in other nonrelativistic approaches is kept. Results are finite without introducing a cutoff and lead to a Lamb shift in hydrogen of 1030.9 MHz. (Author/JN)
Pions in Large N Quantum Chromodynamics
Weinberg, Steven
2010-12-31
An effective field theory of quarks, gluons, and pions, with the number N of colors treated as large, is proposed as a basis for calculations of hadronic phenomena at moderate energies. The qualitative consequences of the large N limit are similar though not identical to those in pure quantum chromodynamics, but because constituent quark masses appear in the effective Lagrangian, the 't Hooft coupling in the effective theory need not be strong at moderate energies. To leading order in 1/N the effective theory is renormalizable, with only a finite number of terms in the Lagrangian.
Clothed Particles in Quantum Electrodynamics and Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Shebeko, Alexander
2016-03-01
The notion of clothing in quantum field theory (QFT), put forward by Greenberg and Schweber and developed by M. Shirokov, is applied in quantum electrodynamics (QED) and quantum chromodynamics (QCD). Along the guideline we have derived a novel analytic expression for the QED Hamiltonian in the clothed particle representation (CPR). In addition, we are trying to realize this notion in QCD (to be definite for the gauge group SU(3)) when drawing parallels between QCD and QED.
Weizsacker-Williams approximation in quantum chromodynamics
NASA Astrophysics Data System (ADS)
Kovchegov, Yuri V.
The Weizsacker-Williams approximation for a large nucleus in quantum chromodynamics is developed. The non-Abelian Wieizsacker Williams field for a large ultrarelativistic nucleus is constructed. This field is an exact solution of the classical Yang-Mills equations of motion in light cone gauge. The connection is made to the McLerran- Venugopalan model of a large nucleus, and the color charge density for a nucleus in this model is found. The density of states distribution, as a function of color charge density, is proved to be Gaussian. We construct the Feynman diagrams in the light cone gauge which correspond to the classical Weizsacker Williams field. Analyzing these diagrams we obtain a limitation on using the quasi-classical approximation for nuclear collisions.
Hadronic and nuclear phenomena in quantum chromodynamics
Brodsky, S.J.
1987-06-01
Many of the key issues in understanding quantum chromodynamics involves processes at intermediate energies. We discuss a range of hadronic and nuclear phenomena - exclusive processes, color transparency, hidden color degrees of freedom in nuclei, reduced nuclear amplitudes, jet coalescence, formation zone effects, hadron helicity selection rules, spin correlations, higher twist effects, and nuclear diffraction - as tools for probing hadron structure and the propagation of quark and gluon jets in nuclei. Many of these processes can be studied in electroproduction, utilizing internal targets in storage rings. We also review several areas where there has been significant theoretical progress in determining the form of hadron and nuclear wavefunctions, including QCD sum rules, lattice gauge theory, and discretized light-cone quantization. 98 refs., 40 figs., 2 tabs.
Novel nuclear phenomena in quantum chromodynamics
Brodsky, S.J.
1987-08-01
Many of the key issues in understanding quantum chromodynamics involve processes in nuclear targets at intermediate energies. A range of hadronic and nuclear phenomena-exclusive processes, color transparency, hidden color degrees of freedom in nuclei, reduced nuclear amplitudes, jet coalescence, formation zone effects, hadron helicity selection rules, spin correlations, higher twist effects, and nuclear diffraction were discussed as tools for probing hadron structure and the propagation of quark and gluon jets in nuclei. Several areas were also reviewed where there has been significant theoretical progress determining the form of hadron and nuclear wave functions, including QCD sum rules, lattice gauge theory, and discretized light-cone quantization. A possible interpretation was also discussed of the large spin correlation A/sub NN/ in proton-proton scattering, and how relate this effect to an energy and angular dependence of color transparency in nuclei. 76 refs., 24 figs.
Quantum Chromodynamics and Nuclear Physics at Extreme Energy Density
Mueller, B.; Bass, S.A.; Chandrasekharan, S.; Mehen, T.; Springer, R.P.
2005-11-07
The report describes research in theoretical quantum chromodynamics, including effective field theories of hadronic interactions, properties of strongly interacting matter at extreme energy density, phenomenology of relativistic heavy ion collisions, and algorithms and numerical simulations of lattice gauge theory and other many-body systems.
Tetraquark mesons in large-N quantum chromodynamics.
Weinberg, Steven
2013-06-28
It is argued that exotic mesons consisting of two quarks and two antiquarks are not ruled out in quantum chromodynamics with a large number N of colors, as generally thought. Tetraquarks of one class are typically long-lived, with decay rates proportional to 1/N.
Where is the continuum in lattice quantum chromodynamics?
NASA Technical Reports Server (NTRS)
Kennedy, A. D.; Pendleton, B. J.; Kuti, J.; Meyer, S.
1985-01-01
A Monte Carlo calculation of the quark-liberating phase transition in lattice quantum chromodynamics is presented. The transition temperature as a function of the lattice coupling g does not scale according to the perturbative beta function for 6/g-squared less than 6.1. Finite-size scaling is used in analyzing the properties of the lattice system near the transition point.
Unification of Einstein's Gravity with Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Sarfatti, Jack
2010-02-01
The four tetrad and six spin-connection Cartan 1-forms of Einstein's GeoMetroDynamic (GMD) field emerge from the eight virtual gluon macro-quantum coherent QCD post-inflation vacuum condensates that form in the inflationary phase transition. This joint emergence of gravity and the strong force is similar to the emergence of irrotational superflow with vortex defects in liquid helium below the Lambda Point. Repulsive dark energy is from the residual random virtual bosons that did not cohere in the moment of inflation. Similarly, attractive dark matter is from the residual random virtual fermion-antifermion pairs. Therefore, I predict that the LHC will not detect any on-mass-shell real particles that can explain φDM˜0.23. As first suggested by Abdus Salam (f-gravity) the low energy tail of the nuclear force can be explained as strong short-range Yukawa gravity. QCD's IR confinement and UV asymptotic freedom are elementary consequences in this simple model. )
Quantum chromodynamics near the confinement limit
Quigg, C.
1985-09-01
These nine lectures deal at an elementary level with the strong interaction between quarks and its implications for the structure of hadrons. Quarkonium systems are studied as a means for measuring the interquark interaction. This is presumably (part of) the answer a solution to QCD must yield, if it is indeed the correct theory of the strong interactions. Some elements of QCD are reviewed, and metaphors for QCD as a confining theory are introduced. The 1/N expansion is summarized as a way of guessing the consequences of QCD for hadron physics. Lattice gauge theory is developed as a means for going beyond perturbation theory in the solution of QCD. The correspondence between statistical mechanics, quantum mechanics, and field theory is made, and simple spin systems are formulated on the lattice. The lattice analog of local gauge invariance is developed, and analytic methods for solving lattice gauge theory are considered. The strong-coupling expansion indicates the existence of a confining phase, and the renormalization group provides a means for recovering the consequences of continuum field theory. Finally, Monte Carlo simulations of lattice theories give evidence for the phase structure of gauge theories, yield an estimate for the string tension characterizing the interquark force, and provide an approximate description of the quarkonium potential in encouraging good agreement with what is known from experiment.
Least-squares finite element methods for quantum chromodynamics
Ketelsen, Christian; Brannick, J; Manteuffel, T; Mccormick, S
2008-01-01
A significant amount of the computational time in large Monte Carlo simulations of lattice quantum chromodynamics (QCD) is spent inverting the discrete Dirac operator. Unfortunately, traditional covariant finite difference discretizations of the Dirac operator present serious challenges for standard iterative methods. For interesting physical parameters, the discretized operator is large and ill-conditioned, and has random coefficients. More recently, adaptive algebraic multigrid (AMG) methods have been shown to be effective preconditioners for Wilson's discretization of the Dirac equation. This paper presents an alternate discretization of the Dirac operator based on least-squares finite elements. The discretization is systematically developed and physical properties of the resulting matrix system are discussed. Finally, numerical experiments are presented that demonstrate the effectiveness of adaptive smoothed aggregation ({alpha}SA ) multigrid as a preconditioner for the discrete field equations resulting from applying the proposed least-squares FE formulation to a simplified test problem, the 2d Schwinger model of quantum electrodynamics.
Condensates in Quantum Chromodynamics and the Cosmological Constant
Brodsky, Stanley J.; Shrock, Robert
2009-05-08
Casher and Susskind have noted that in the light-front description, spontaneous chiral symmetry breaking in quantum chromodynamics (QCD) is a property of hadronic wavefunctions and not of the vacuum. Here we show from several physical perspectives that, because of color confinement, quark and gluon QCD condensates are associated with the internal dynamics of hadrons. We discuss condensates using condensed matter analogues, the AdS/CFT correspondence, and the Bethe-Salpeter/Dyson-Schwinger approach for bound states. Our analysis is in agreement with the Casher and Susskind model and the explicit demonstration of 'in-hadron' condensates by Roberts et al., using the Bethe-Salpeter/Dyson-Schwinger formalism for QCD bound states. These results imply that QCD condensates give zero contribution to the cosmological constant, since all of the gravitational effects of the in-hadron condensates are already included in the normal contribution from hadron masses.
Condensates in quantum chromodynamics and the cosmological constant
Brodsky, Stanley J.; Shrock, Robert
2011-01-01
Casher and Susskind [Casher A, Susskind L (1974) Phys Rev 9:436–460] have noted that in the light-front description, spontaneous chiral symmetry breaking is a property of hadronic wavefunctions and not of the vacuum. Here we show from several physical perspectives that, because of color confinement, quark and gluon condensates in quantum chromodynamics (QCD) are associated with the internal dynamics of hadrons. We discuss condensates using condensed matter analogues, the Anti de Sitter/conformal field theory correspondence, and the Bethe–Salpeter–Dyson–Schwinger approach for bound states. Our analysis is in agreement with the Casher and Susskind model and the explicit demonstration of “in-hadron” condensates by Roberts and coworkers [Maris P, Roberts CD, Tandy PC (1998) Phys Lett B 420:267–273], using the Bethe–Salpeter–Dyson–Schwinger formalism for QCD-bound states. These results imply that QCD condensates give zero contribution to the cosmological constant, because all of the gravitational effects of the in-hadron condensates are already included in the normal contribution from hadron masses.
Quantum Chromodynamics -- The Perfect Yang-Mills Gauge Field Theory
NASA Astrophysics Data System (ADS)
Gross, David
David Gross: My talk today is about the most beautiful of all Yang-Mills Theories (non-Abelian gauge theories), the theory of the strong nuclear interactions, Quantum Chromodynamics, QCD. We are celebrating 60 years of the publication of a remarkable paper which introduced the concept of non-Abelian local gauge symmetries, now called the Yang-Mills theory, to physics. In the introduction to this paper it is noted that the usual principle of isotopic spin symmetry is not consistent with the concept of localized fields. This sentence has drawn attention over the years because the usual principle of isotopic spin symmetry is consistent, it is just not satisfactory. The authors, Yang and Mills, introduced a more satisfactory notion of local symmetry which did not require one to rotate (in isotopic spin space) the whole universe at once to achieve the symmetry transformation. Global symmetries are thus are similar to `action at a distance', whereas Yang-Mills theory is manifestly local...
Current-Current Interactions, Dynamical Symmetry - and Quantum Chromodynamics.
NASA Astrophysics Data System (ADS)
Neuenschwander, Dwight Edward, Jr.
Quantum Chromodynamics with massive gluons (gluon mass (TBOND) xm(,p)) in a contact-interaction limit called CQCD (strong coupling g (--->) (INFIN); x (--->) (INFIN)), despite its non-renormalizability and lack of hope of confinement, is nevertheless interesting for at least two reasons. (1) Some authors have suggested a relation between 4-Fermi and Yang-Mills theories. If g/x('2) << 1, then CQCD is not merely a 4-Fermi interaction, but includes 4, 6, 8, ...-Fermi non-Abelian contact interactions. (2) With the possibility of infrared slavery, perturbative evaluation of QCD in the infrared is a dubious practice. However, if g('2)/x('2) << 1 in CQCD, then the simplest 4-Fermi interaction is dominant, and CQCD admits perturbative treatment, but only in the infrared. With the dominant interaction, a dynamical Nambu-Goldstone realization of chiral symmetry -breaking (XSB) is found. Although in QCD the relation between confinement and XSB is controversial, XSB occurs in CQCD provided confinement is sacrificed.
NASA Astrophysics Data System (ADS)
Adams, Allan; Carr, Lincoln D.; Schäfer, Thomas; Steinberg, Peter; Thomas, John E.
2012-11-01
Strongly correlated quantum fluids are phases of matter that are intrinsically quantum mechanical and that do not have a simple description in terms of weakly interacting quasiparticles. Two systems that have recently attracted a great deal of interest are the quark-gluon plasma, a plasma of strongly interacting quarks and gluons produced in relativistic heavy ion collisions, and ultracold atomic Fermi gases, very dilute clouds of atomic gases confined in optical or magnetic traps. These systems differ by 19 orders of magnitude in temperature, but were shown to exhibit very similar hydrodynamic flows. In particular, both fluids exhibit a robustly low shear viscosity to entropy density ratio, which is characteristic of quantum fluids described by holographic duality, a mapping from strongly correlated quantum field theories to weakly curved higher dimensional classical gravity. This review explores the connection between these fields, and also serves as an introduction to the focus issue of New Journal of Physics on ‘Strongly Correlated Quantum Fluids: From Ultracold Quantum Gases to Quantum Chromodynamic Plasmas’. The presentation is accessible to the general physics reader and includes discussions of the latest research developments in all three areas.
Multi-Hadron Observables from Lattice Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Hansen, Maxwell T.
We describe formal work that relates the finite-volume spectrum in a quantum field theory to scattering and decay amplitudes. This is of particular relevance to numerical calculations performed using Lattice Quantum Chromodynamics (LQCD). Correlators calculated using LQCD can only be determined on the Euclidean time axis. For this reason the standard method of determining scattering amplitudes via the Lehmann-Symanzik-Zimmermann reduction formula cannot be employed. By contrast, the finite-volume spectrum is directly accessible in LQCD calculations. Formalism for relating the spectrum to physical scattering observables is thus highly desirable. In this thesis we develop tools for extracting physical information from LQCD for four types of observables. First we analyze systems with multiple, strongly-coupled two-scalar channels. Here we accommodate both identical and nonidentical scalars, and in the latter case allow for degenerate as well as nondegenerate particle masses. Using relativistic field theory, and summing to all orders in perturbation theory, we derive a result relating the finite-volume spectrum to the two-to-two scattering amplitudes of the coupled-channel theory. This generalizes the formalism of Martin Luscher for the case of single-channel scattering. Second we consider the weak decay of a single particle into multiple, coupled two-scalar channels. We show how the finite-volume matrix element extracted in LQCD is related to matrix elements of asymptotic two-particle states, and thus to decay amplitudes. This generalizes work by Laurent Lellouch and Martin Luscher. Third we extend the method for extracting matrix elements by considering currents which insert energy, momentum and angular momentum. This allows one to extract transition matrix elements and form factors from LQCD. Finally we look beyond two-particle systems to those with three-particles in asymptotic states. Working again to all orders in relativistic field theory, we derive a relation
Multi-Hadron Observables from Lattice Quantum Chromodynamics
Hansen, Maxwell
2014-01-01
We describe formal work that relates the nite-volume spectrum in a quantum eld theory to scattering and decay amplitudes. This is of particular relevance to numerical calculations performed using Lattice Quantum Chromodynamics (LQCD). Correlators calculated using LQCD can only be determined on the Euclidean time axis. For this reason the standard method of determining scattering amplitudes via the Lehmann-Symanzik-Zimmermann reduction formula cannot be employed. By contrast, the nite-volume spectrum is directly accessible in LQCD calculations. Formalism for relating the spectrum to physical scattering observables is thus highly desirable. In this thesis we develop tools for extracting physical information from LQCD for four types of observables. First we analyze systems with multiple, strongly-coupled two-scalar channels. Here we accommodate both identical and nonidentical scalars, and in the latter case allow for degenerate as well as nondegenerate particle masses. Using relativistic eld theory, and summing to all orders in perturbation theory, we derive a result relating the nite-volume spectrum to the two-to-two scattering amplitudes of the coupled-channel theory. This generalizes the formalism of Martin L uscher for the case of single-channel scattering. Second we consider the weak decay of a single particle into multiple, coupled two-scalar channels. We show how the nite-volume matrix element extracted in LQCD is related to matrix elements of asymptotic two-particle states, and thus to decay amplitudes. This generalizes work by Laurent Lellouch and Martin L uscher. Third we extend the method for extracting matrix elements by considering currents which insert energy, momentum and angular momentum. This allows one to extract transition matrix elements and form factors from LQCD. Finally we look beyond two-particle systems to those with three-particles in asymptotic states. Working again to all orders in relativistic eld theory, we derive a relation between the
Quantum chromodynamic quark model study of hadron and few hadron systems
Ji, Chueng-Ryong.
1990-10-01
This report details research progress and results obtained during the five month period July 1, 1990 to November 30, 1990. The research project, entitled Quantum Chromodynamic Quark Model Study of Hadron and Few Hadron Systems,'' is supported by grant FG05-90ER40589 between North Carolina State University and the United States Department of Energy. This is a research program addressing theoretical investigations of hadron structure and reactions using quantum chromodynamic quark models. The new, significant research results are briefly summarized in the following sections.
Classical and quantum mechanics of the nonrelativistic Snyder model
NASA Astrophysics Data System (ADS)
Mignemi, S.
2011-07-01
The Snyder model is an example of noncommutative spacetime admitting a fundamental length scale β and invariant under Lorentz transformations, that can be interpreted as a realization of the doubly special relativity axioms. Here, we consider its nonrelativistic counterpart, i.e. the Snyder model restricted to three-dimensional Euclidean space. We discuss the classical and the quantum mechanics of a free particle in this framework, and show that they strongly depend on the sign of a coupling constant λ, appearing in the fundamental commutators and proportional to β2. For example, if λ is negative, momenta are bounded. On the contrary, for positive λ, positions and areas are quantized. We also give the exact solution of the harmonic oscillator equations both in the classical and the quantum case, and show that its frequency is energy dependent.
Nonrelativistic quantum mechanics with consideration of influence of fundamental environment
Gevorkyan, A. S.
2013-08-15
Spontaneous transitions between bound states of an atomic system, the 'Lamb Shift' of energy levels and many other phenomena in real nonrelativistic quantum systems are connected with the influence of the quantum vacuum fluctuations (fundamental environment (FE)), which are impossible to consider in the framework of standard quantum-mechanical approaches. The joint system quantum system (QS) and FE is described in the framework of the stochastic differential equation (SDE) of Langevin-Schroedinger type and is defined on the extended space Double-Struck-Capital-R {sup 3} Circled-Times {Xi}{sup n}, where Double-Struck-Capital-R {sup 3} and {Xi}{sup n} are the Euclidean and functional spaces, respectively. The method of stochastic density matrix is developed and the von Neumann equation for reduced density matrix of QS with FE is generalized. The entropy of QS entangled with FE is defined and investigated. It is proved that the interaction of QS with the environment leads to emerging structures of various topologies which present new quantum-field properties of QS. It is shown that when the physical system (irrelatively to its being micro ormacro) breaks up into two fragments by means of FE, there arises between these fragments a nonpotential interaction which does not disappear at large distances.
A signed particle formulation of non-relativistic quantum mechanics
Sellier, Jean Michel
2015-09-15
A formulation of non-relativistic quantum mechanics in terms of Newtonian particles is presented in the shape of a set of three postulates. In this new theory, quantum systems are described by ensembles of signed particles which behave as field-less classical objects which carry a negative or positive sign and interact with an external potential by means of creation and annihilation events only. This approach is shown to be a generalization of the signed particle Wigner Monte Carlo method which reconstructs the time-dependent Wigner quasi-distribution function of a system and, therefore, the corresponding Schrödinger time-dependent wave-function. Its classical limit is discussed and a physical interpretation, based on experimental evidences coming from quantum tomography, is suggested. Moreover, in order to show the advantages brought by this novel formulation, a straightforward extension to relativistic effects is discussed. To conclude, quantum tunnelling numerical experiments are performed to show the validity of the suggested approach.
Stochastic vacuum of quantum chromodynamics as an environment for color particles
NASA Astrophysics Data System (ADS)
Kuvshinov, V.; Bagashov, E.
2016-05-01
The behavior of quarks is described within approaches used in quantum mechanics and related disciplines (quantum optics and quantum theory of information). The stochastic vacuum of quantum chromodynamics is treated as an environment (closed pool) for color particles (quarks). Their interaction results in a loss of information on the quark color state and consequently in the impossibility of observing it (the confinement of quarks). The processes are described using quantities of the quantum theory of information, such as von Neumann entropy, fidelity, and purity.
Variance of the Quantum Dwell Time for a Nonrelativistic Particle
NASA Technical Reports Server (NTRS)
Hahne, Gerhard
2012-01-01
Munoz, Seidel, and Muga [Phys. Rev. A 79, 012108 (2009)], following an earlier proposal by Pollak and Miller [Phys. Rev. Lett. 53, 115 (1984)] in the context of a theory of a collinear chemical reaction, showed that suitable moments of a two-flux correlation function could be manipulated to yield expressions for the mean quantum dwell time and mean square quantum dwell time for a structureless particle scattering from a time-independent potential energy field between two parallel lines in a two-dimensional spacetime. The present work proposes a generalization to a charged, nonrelativistic particle scattering from a transient, spatially confined electromagnetic vector potential in four-dimensional spacetime. The geometry of the spacetime domain is that of the slab between a pair of parallel planes, in particular those defined by constant values of the third (z) spatial coordinate. The mean Nth power, N = 1, 2, 3, . . ., of the quantum dwell time in the slab is given by an expression involving an N-flux-correlation function. All these means are shown to be nonnegative. The N = 1 formula reduces to an S-matrix result published previously [G. E. Hahne, J. Phys. A 36, 7149 (2003)]; an explicit formula for N = 2, and of the variance of the dwell time in terms of the S-matrix, is worked out. A formula representing an incommensurability principle between variances of the output-minus-input flux of a pair of dynamical variables (such as the particle s time flux and others) is derived.
Lattice studies of quantum chromodynamics-like theories with many fermionic degrees of freedom.
DeGrand, Thomas
2011-07-13
I give an elementary introduction to the study of gauge theories coupled to fermions with many degrees of freedom. Besides their intrinsic interest, these theories are candidates for non-perturbative extensions of the Higgs sector of the standard model. While related to quantum chromodynamics, these systems can exhibit very different behaviour from it: they can possess a running gauge coupling with an infrared-attractive fixed point. I briefly survey recent lattice work in this area.
Resonances in Coupled πK-ηK Scattering from Quantum Chromodynamics
Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.; Wilson, David J.
2014-10-01
Using first-principles calculation within Quantum Chromodynamics, we are able to reproduce the pattern of experimental strange resonances which appear as complex singularities within coupled πK, ηK scattering amplitudes. We make use of numerical computation within the lattice discretized approach to QCD, extracting the energy dependence of scattering amplitudes through their relation- ship to the discrete spectrum of the theory in a finite-volume, which we map out in unprecedented detail.
QCD (Quantum Chromo-Dynamics) with dynamical fermions on the connection machine
Baillie, C.F.; Brickner, R.G.; Gupta, R.; Johnsson, L. . Concurrent Computation Project; Los Alamos National Lab., NM; Thinking Machines Corp., Cambridge, MA )
1989-01-01
We have implemented Quantum Chromo-Dynamics (QCD) on the massively parallel Connection Machine in *Lisp. The code uses dynamical Wilson fermions and the Hybrid Monte Carlo Algorithm (HMCA) to update the lattice. We describe our program and give performance measurements for it. With no tuning or optimization, the code runs at approximately 500 to 1000 MFLOPS on a 64-K Connection Machine, model CM-2, depending on the VP ratio.
Time as an Observable in Nonrelativistic Quantum Mechanics
NASA Technical Reports Server (NTRS)
Hahne, G. E.
2003-01-01
The argument follows from the viewpoint that quantum mechanics is taken not in the usual form involving vectors and linear operators in Hilbert spaces, but as a boundary value problem for a special class of partial differential equations-in the present work, the nonrelativistic Schrodinger equation for motion of a structureless particle in four- dimensional space-time in the presence of a potential energy distribution that can be time-as well as space-dependent. The domain of interest is taken to be one of two semi-infinite boxes, one bounded by two t=constant planes and the other by two t=constant planes. Each gives rise to a characteristic boundary value problem: one in which the initial, input values on one t=constant wall are given, with zero asymptotic wavefunction values in all spatial directions, the output being the values on the second t=constant wall; the second with certain input values given on both z=constant walls, with zero asymptotic values in all directions involving time and the other spatial coordinates, the output being the complementary values on the z=constant walls. The first problem corresponds to ordinary quantum mechanics; the second, to a fully time-dependent version of a problem normally considered only for the steady state (time-independent Schrodinger equation). The second problem is formulated in detail. A conserved indefinite metric is associated with space-like propagation, where the sign of the norm of a unidirectional state corresponds to its spatial direction of travel.
Hoang, Andre H.; Ruiz-Femenia, Pedro
2006-12-01
We discuss the form and construction of general color singlet heavy particle-antiparticle pair production currents for arbitrary quantum numbers, and issues related to evanescent spin operators and scheme dependences in nonrelativistic QCD in n=3-2{epsilon} dimensions. The anomalous dimensions of the leading interpolating currents for heavy quark and colored scalar pairs in arbitrary {sup 2S+1}L{sub J} angular-spin states are determined at next-to-leading order in the nonrelativistic power counting.
Quarks, QCD (quantum chromodynamics) and the real world of experimental data
Lipkin, H.J.
1987-07-01
The experimental evidence that supports quantum chromodynamics as the theory that describes how the quarks interact is briefly discussed. The indications of the existence of quarks are reviewed, and calculation of hadron masses is discussed. Additional evidence of hadron substructure as seen in the antiproton is reviewed. Arguments for the existence of color as the ''charge'' carried by quarks by which they interact are given. Hadron masses and the hyperfine interaction are presented, followed by more exotic quark systems and a study of multiquark systems. Weak interactions in the quark model are discussed. (LEW)
Ardenghi, Juan S.; Castagnino, M.; Campoamor-Stursberg, R.
2009-10-15
The nonrelativistic limit of the centrally extended Poincare group is considered and their consequences in the modal Hamiltonian interpretation of quantum mechanics are discussed [O. Lombardi and M. Castagnino, Stud. Hist. Philos. Mod. Phys 39, 380 (2008); J. Phys, Conf. Ser. 128, 012014 (2008)]. Through the assumption that in quantum field theory the Casimir operators of the Poincare group actualize, the nonrelativistic limit of the latter group yields to the actualization of the Casimir operators of the Galilei group, which is in agreement with the actualization rule of previous versions of modal Hamiltonian interpretation [Ardenghi et al., Found. Phys. (submitted)].
Super classical quantum mechanics: The best interpretation of nonrelativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Lamb, Willis E.
2001-04-01
It has been shown that Newtonian classical mechanics (NCM) suffers from several kinds of chaotic indeterminacies. That means, a large set of problems treated with NCM gives results which are in wild disagreement with observation. In the present paper, these shortcomings are repaired in a simple, obvious, and essentially unique manner. The NCM theory is thereby transformed into a new theory which is fully equivalent to the Heisenberg, Schrödinger, and Dirac nonrelativistic quantum mechanics, with the vital addition of Born's probabilistic interpretation of the wave function built in from the start. I call this new theory "super classical quantum mechanics" (SCQM). Using Ehrenfest's theorem of 1927, the classical limit of the new theory, SCQM, is seen to give exactly the results expected of the repaired Newtonian theory of classical mechanics.
Ji, C.R.
1999-04-01
This report details research progress and results obtained during the entire period of the research project. In compliance with grant requirements the Principal Investigator, Professor Chueng-Ryong Ji, has conducted a research program addressing theoretical investigations of hadron structure and reactions using quantum chromodynamic quark models. This Principal Investigator has devoted 50% of his time during the academic year and 100% of his time in the summer. This percent effort has continued during the entire period of the grant. The new, significant research results are briefly summarized in this report. Finally, full, detailed descriptions of completed work can be found in the project publications which are listed at the end of this technical report.
Resonant π+γ→π+π0 amplitude from Quantum Chromodynamics
Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.
2015-12-08
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude formore » $$\\pi\\pi \\to \\pi\\gamma^\\star$$, as a function of the energy of the $$\\pi\\pi$$ pair and the virtuality of the photon, in the kinematic regime where $$\\pi\\pi$$ couples strongly to the unstable $$\\rho$$ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to $$m_\\pi \\approx 400$$ MeV. As a result, we obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the $$\\rho$$ pole and identify from its residue the $$\\rho \\to \\pi\\gamma^\\star$$ form-factor.« less
NASA Astrophysics Data System (ADS)
Azaria, P.; Konik, R. M.; Lecheminant, P.; Pálmai, T.; Takács, G.; Tsvelik, A. M.
2016-08-01
In this paper we study a (1 +1 )-dimensional version of the famous Nambu-Jona-Lasinio model of quantum chromodynamics (QCD2) both at zero and at finite baryon density. We use nonperturbative techniques (non-Abelian bosonization and the truncated conformal spectrum approach). When the baryon chemical potential, μ , is zero, we describe the formation of fermion three-quark (nucleons and Δ baryons) and boson (two-quark mesons, six-quark deuterons) bound states. We also study at μ =0 the formation of a topologically nontrivial phase. When the chemical potential exceeds the critical value and a finite baryon density appears, the model has a rich phase diagram which includes phases with a density wave and superfluid quasi-long-range (QLR) order, as well as a phase of a baryon Tomonaga-Luttinger liquid (strange metal). The QLR order results in either a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).
Parallelizing the QUDA Library for Multi-GPU Calculations in Lattice Quantum Chromodynamics
Ronald Babich, Michael Clark, Balint Joo
2010-11-01
Graphics Processing Units (GPUs) are having a transformational effect on numerical lattice quantum chromodynamics (LQCD) calculations of importance in nuclear and particle physics. The QUDA library provides a package of mixed precision sparse matrix linear solvers for LQCD applications, supporting single GPUs based on NVIDIA's Compute Unified Device Architecture (CUDA). This library, interfaced to the QDP++/Chroma framework for LQCD calculations, is currently in production use on the "9g" cluster at the Jefferson Laboratory, enabling unprecedented price/performance for a range of problems in LQCD. Nevertheless, memory constraints on current GPU devices limit the problem sizes that can be tackled. In this contribution we describe the parallelization of the QUDA library onto multiple GPUs using MPI, including strategies for the overlapping of communication and computation. We report on both weak and strong scaling for up to 32 GPUs interconnected by InfiniBand, on which we sustain in excess of 4 Tflops.
Resonant π^{+}γ→π^{+}π^{0} Amplitude from Quantum Chromodynamics.
Briceño, Raúl A; Dudek, Jozef J; Edwards, Robert G; Shultz, Christian J; Thomas, Christopher E; Wilson, David J
2015-12-11
We present the first ab initio calculation of a radiative transition of a hadronic resonance within quantum chromodynamics (QCD). We compute the amplitude for ππ→πγ^{⋆}, as a function of the energy of the ππ pair and the virtuality of the photon, in the kinematic regime where ππ couples strongly to the unstable ρ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to m_{π}≈400 MeV. We obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the ρ pole and identify from its residue the ρ→πγ^{⋆} form factor. PMID:26705626
Gauge invariant description of heavy quark bound states in quantum chromodynamics
Moore, S.E.
1980-08-01
A model for a heavy quark meson is proposed in the framework of a gauge-invariant version of quantum chromodynamics. The field operators in this formulation are taken to be Wilson loops and strings with quark-antiquark ends. The fundamental differential equations of point-like Q.C.D. are expressed as variational equations of the extended loops and strings. The 1/N expansion is described, and it is assumed that nonleading effects such as intermediate quark pairs and nonplanar gluonic terms can be neglected. The action of the Hamiltonian in the A/sub 0/ = 0 gauge on a string operator is derived. A trial meson wave functional is constructed consisting of a path-averaged string operator applied to the full vacuum. A Gaussian in the derivative of the path location is assumed for the minimal form of the measure over paths. A variational parameter is incorporated in the measure as the exponentiated coefficient of the squared path location. The expectation value of the Hamiltonian in the trial state is evaluated for the assumption that the negative logarithm of the expectation value of a Wilson loop is proportional to the loop area. The energy is then minimized by deriving the equivalent quantum mechanical Schroedinger's equation and using the quantum mechanical 1/n expansion to estimate the effective eigenvalues. It is found that the area law behavior of the Wilson loop implies a nonzero best value of the variational parameter corresponding to a quantum broadening of the flux tube.
Rehman, M. A.; Qureshi, M. N. S.; Shah, H. A.; Masood, W.
2015-10-15
Nonlinear circularly polarized Alfvén waves are studied in magnetized nonrelativistic, relativistic, and ultrarelativistic degenerate Fermi plasmas. Using the quantum hydrodynamic model, Zakharov equations are derived and the Sagdeev potential approach is used to investigate the properties of the electromagnetic solitary structures. It is seen that the amplitude increases with the increase of electron density in the relativistic and ultrarelativistic cases but decreases in the nonrelativistic case. Both right and left handed waves are considered, and it is seen that supersonic, subsonic, and super- and sub-Alfvénic solitary structures are obtained for different polarizations and under different relativistic regimes.
Geometric approach to non-relativistic quantum dynamics of mixed states
NASA Astrophysics Data System (ADS)
Gimeno, Vicent; Sotoca, Jose M.
2013-05-01
In this paper we propose a geometrization of the non-relativistic quantum mechanics for mixed states. Our geometric approach makes use of the Uhlmann's principal fibre bundle to describe the space of mixed states and as a novelty tool, to define a dynamic-dependent metric tensor on the principal manifold, such that the projection of the geodesic flow to the base manifold gives the temporal evolution predicted by the von Neumann equation. Using that approach we can describe every conserved quantum observable as a Killing vector field, and provide a geometric proof for the Poincaré quantum recurrence in a physical system with finite energy levels.
Instantaneous Spreading Versus Space Localization for Nonrelativistic Quantum Systems
NASA Astrophysics Data System (ADS)
Coutinho, F. A. B.; Wreszinski, W. F.
2016-08-01
A theorem of Hegerfeldt (Kielanowski et al. 1998) establishes, for a class of quantum systems, a dichotomy between those which are permanently localized in a bounded region of space, and those exhibiting instantaneous spreading. We analyze in some detail the physical inconsistencies which follow from both of these options, and formulate which, in our view, are the basic open problems.
New parton distribution functions from a global analysis of quantum chromodynamics
NASA Astrophysics Data System (ADS)
Dulat, Sayipjamal; Hou, Tie-Jiun; Gao, Jun; Guzzi, Marco; Huston, Joey; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C.-P.
2016-02-01
We present new parton distribution functions (PDFs) at next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged-lepton rapidity asymmetry data, as well as the use of a more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. For completeness, we also present the CT14 PDFs determined at the LO and the NLO in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various αs values and additional sets in general-mass variable flavor number schemes, to deal with heavy partons, with up to three, four, and six active flavors.
The application of light-cone quantization to quantum chromodynamics in one-plus-one dimensions
Hornbostel, K.J.
1988-12-01
Formal and computational aspects of light cone quantization are studied by application to quantum chromodynamics (QCD) in one spatial plus one temporal dimension. This quantization scheme, which has been extensively applied to perturbative calculations, is shown to provide an intuitively appealing and numerically tractable approach to non-perturbative computations as well. In the initial section, a light-cone quantization procedure is developed which incorporates fields on the boundaries. This allows for the consistent treatment of massless fermions and the construction of explicitly conserved momentum and charge operators. The next section, which comprises the majority of this work, focuses on the numerical solution of the light-cone Schrodinger equation for bound states. The state space is constructed and the Hamiltonian is evaluated and diagonalized by computer for arbitrary number of colors, baryon number and coupling constant strength. As a result, the full spectrum of mesons and baryons and their associated wavefunctions are determined. These results are compared with those which exist from other approaches to test the reliability of the method. The program also provides a preliminary test for the feasibility of, and an opportunity to develop approximation schemes for, an attack on three-plus-one dimensional QCD. Finally, analytic results are presented which include a discussion of integral equations for wavefunctions and their endpoint behavior. Solutions for hadronic masses and wavefunctions in the limits of both large and small quark mass are discussed. 49 refs., 32 figs., 10 tabs.
Maximal Wavelength of Confined Quarks and Gluons and Properties of Quantum Chromodynamics
Brodsky, Stanley J.; Shrock, Robert; /YITP, Stony Brook
2008-08-01
Because quarks and gluons are confined within hadrons, they have a maximum wavelength of order the confinement scale. Propagators, normally calculated for free quarks and gluons using Dyson-Schwinger equations, are modified by bound-state effects in close analogy to the calculation of the Lamb shift in atomic physics. Because of confinement, the effective quantum chromodynamic coupling stays finite in the infrared. The quark condensate which arises from spontaneous chiral symmetry breaking in the bound state Dyson-Schwinger equation is the expectation value of the operator {bar q}q evaluated in the background of the fields of the other hadronic constituents, in contrast to a true vacuum expectation value. Thus quark and gluon condensates reside within hadrons. The effects of instantons are also modified. We discuss the implications of the maximum quark and gluon wavelength for phenomena such as deep inelastic scattering and annihilation, the decay of heavy quarkonia, jets, and dimensional counting rules for exclusive reactions. We also discuss implications for the zero-temperature phase structure of a vectorial SU(N) gauge theory with a variable number N{sub f} of massless fermions.
Current-current interactions, dynamical symmetry-breaking, and quantum chromodynamics
Neuenschwander, D.E. Jr.
1983-01-01
Quantum Chromodynamics with massive gluons (gluon mass triple bond xm/sub p/) in a contact-interaction limit called CQCD (strong coupling g..-->..infinity; x..-->..infinity), despite its non-renormalizability and lack of hope of confinement, is nevertheless interesting for at least two reasons. Some authors have suggested a relation between 4-Fermi and Yang-Mills theories. If g/x/sup 2/ much less than 1, then CQCD is not merely a 4-Fermi interaction, but includes 4,6,8 etc-Fermi non-Abelian contact interactions. With possibility of infrared slavery, perturbative evaluation of QCD in the infrared is a dubious practice. However, if g/sup 2//x/sup 2/ much less than 1 in CQCD, then the simplest 4-Fermi interaction is dominant, and CQCD admits perturbative treatment, but only in the infrared. With the dominant interaction, a dynamical Nambu-Goldstone realization of chiral symmetry-breaking (XSB) is found. Although in QCD the relation between confinement and XSB is controversial, XSB occurs in CQCD provided confinement is sacrificed.
New parton distribution functions from a global analysis of quantum chromodynamics
Dulat, Sayipjamal; Hou, Tie -Jiun; Gao, Jun; Guzzi, Marco; Nadolsky, Pavel; Pumplin, Jon; Schmidt, Carl; Stump, Daniel; Yuan, C. -P.; Huston, Joey
2016-02-16
Here, we present new parton distribution functions (PDFs) up to next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments and the new D0 charged lepton rapidity asymmetry data, as well as the use of more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. Formore » completeness, we also present the CT14 PDFs determined at the leading order (LO) and the next-to-leading order (NLO) in QCD. Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various αs values and additional sets in general-mass variable flavor number (GM-VFN) schemes, to deal with heavy partons, with up to 3, 4, and 6 active flavors.« less
Searching for new physics at the frontiers with lattice quantum chromodynamics.
Van de Water, Ruth S
2012-07-01
Numerical lattice-quantum chromodynamics (QCD) simulations, when combined with experimental measurements, allow the determination of fundamental parameters of the particle-physics Standard Model and enable searches for physics beyond-the-Standard Model. We present the current status of lattice-QCD weak matrix element calculations needed to obtain the elements and phase of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and to test the Standard Model in the quark-flavor sector. We then discuss evidence that may hint at the presence of new physics beyond the Standard Model CKM framework. Finally, we discuss two opportunities where we expect lattice QCD to play a pivotal role in searching for, and possibly discovery of, new physics at upcoming high-intensity experiments: rare decays and the muon anomalous magnetic moment. The next several years may witness the discovery of new elementary particles at the Large Hadron Collider (LHC). The interplay between lattice QCD, high-energy experiments at the LHC, and high-intensity experiments will be needed to determine the underlying structure of whatever physics beyond-the-Standard Model is realized in nature.
Woesler, Richard
2007-02-21
The computations of the present text with non-relativistic quantum teleportation equations and special relativity are totally speculative, physically correct computations can be done using quantum field theory, which remain to be done in future. Proposals for what might be called statistical time loop experiments with, e.g., photon polarization states are described when assuming the simplified non-relativistic quantum teleportation equations and special relativity. However, a closed time loop would usually not occur due to phase incompatibilities of the quantum states. Histories with such phase incompatibilities are called inconsistent ones in the present text, and it is assumed that only consistent histories would occur. This is called an exclusion principle for inconsistent histories, and it would yield that probabilities for certain measurement results change. Extended multiple parallel experiments are proposed to use this statistically for transmission of classical information over distances, and regarding time. Experiments might be testable in near future. However, first a deeper analysis, including quantum field theory, remains to be done in future.
Color transparency and the structure of the proton in quantum chromodynamics
Brodsky, S.J.
1989-06-01
Many anomalies suggest that the proton itself is a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrivial proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trivial oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non-negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. As we shall see in this lecture, the apparent discrepancies with experiment are not so much a failure of QCD, but rather symptoms of the complexity and richness of the theory. An important tool for analyzing this complexity is the light-cone Fock state representation of hadron wavefunctions, which provides a consistent but convenient framework for encoding the features of relativistic many-body systems in quantum field theory. 121 refs., 44 figs., 1 tab.
Generalized Lagrangian-Path Representation of Non-Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Tessarotto, Massimo; Cremaschini, Claudio
2016-08-01
In this paper a new trajectory-based representation to non-relativistic quantum mechanics is formulated. This is ahieved by generalizing the notion of Lagrangian path (LP) which lies at the heart of the deBroglie-Bohm " pilot-wave" interpretation. In particular, it is shown that each LP can be replaced with a statistical ensemble formed by an infinite family of stochastic curves, referred to as generalized Lagrangian paths (GLP). This permits the introduction of a new parametric representation of the Schrödinger equation, denoted as GLP-parametrization, and of the associated quantum hydrodynamic equations. The remarkable aspect of the GLP approach presented here is that it realizes at the same time also a new solution method for the N-body Schrödinger equation. As an application, Gaussian-like particular solutions for the quantum probability density function (PDF) are considered, which are proved to be dynamically consistent. For them, the Schrödinger equation is reduced to a single Hamilton-Jacobi evolution equation. Particular solutions of this type are explicitly constructed, which include the case of free particles occurring in 1- or N-body quantum systems as well as the dynamics in the presence of suitable potential forces. In all these cases the initial Gaussian PDFs are shown to be free of the spreading behavior usually ascribed to quantum wave-packets, in that they exhibit the characteristic feature of remaining at all times spatially-localized.
Linear and nonlinear ion-acoustic waves in nonrelativistic quantum plasmas with arbitrary degeneracy
NASA Astrophysics Data System (ADS)
Haas, Fernando; Mahmood, Shahzad
2015-11-01
Linear and nonlinear ion-acoustic waves are studied in a fluid model for nonrelativistic, unmagnetized quantum plasma with electrons with an arbitrary degeneracy degree. The equation of state for electrons follows from a local Fermi-Dirac distribution function and applies equally well both to fully degenerate and classical, nondegenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid for dilute and dense plasmas is proposed. The linear dispersion relation of the ion-acoustic waves is obtained and the ion-acoustic speed is discussed for the limiting cases of extremely dense or dilute systems. In the long-wavelength limit, the results agree with quantum kinetic theory. Using the reductive perturbation method, the appropriate Korteweg-de Vries equation for weakly nonlinear solutions is obtained and the corresponding soliton propagation is analyzed. It is found that soliton hump and dip structures are formed depending on the value of the quantum parameter for the degenerate electrons, which affect the phase velocities in the dispersive medium.
Nonrelativistic quantum dynamics on a cone with and without a constraining potential
Filgueiras, C.; Silva, E. O.; Andrade, F. M.
2012-12-15
In this paper we investigate the bound state problem of nonrelativistic quantum particles on a conical surface. This kind of surface appears as a topological defect in ordinary semiconductors as well as in graphene sheets. Specifically, we compare and discuss the results stemming from two different approaches. In the first one, it is assumed that the charge carriers are bound to the surface by a constraining potential, while the second one is based on the Klein-Gordon type equation on surfaces, without the constraining potential. The main difference between both theories is the presence/absence of a potential which contains the mean curvature of a given surface. This fact changes the dependence of the bound states on the angular momentum l. Moreover, there are bound states that are absent in the Klein-Gordon theory, which instead appear in the Schroedinger one.
Light Nuclei and HyperNuclei from Quantum Chromodynamics in the Limit of SU(3) Flavor Symmetry
Beane, S R; Cohen, S D; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Walker-Loud, A
2013-02-01
The binding energies of a range of nuclei and hypernuclei with atomic number A <= 4 and strangeness |s| <= 2, including the deuteron, di-neutron, H-dibaryon, {sup 3}He, {sub {Lambda}}{sup 3}He, {sub {Lambda}}{sup 4}He, and {sub {Lambda}{Lambda}}{sup 4}He, are calculated in the limit of flavor-SU(3) symmetry at the physical strange quark mass with quantum chromodynamics (without electromagnetic interactions). The nuclear states are extracted from Lattice QCD calculations performed with n{sub f}=3 dynamical light quarks using an isotropic clover discretization of the quark-action in three lattice volumes of spatial extent L ~ 3.4 fm, 4.5 fm and 6.7 fm, and with a single lattice spacing b ~ 0.145 fm.
NASA Astrophysics Data System (ADS)
Bazavov, A.; Bernard, C.; Bouchard, C. M.; DeTar, C.; Di Pierro, M.; El-Khadra, A. X.; Evans, R. T.; Freeland, E. D.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Hetrick, J. E.; Jain, R.; Kronfeld, A. S.; Laiho, J.; Levkova, L.; Mackenzie, P. B.; Neil, E. T.; Oktay, M. B.; Simone, J. N.; Sugar, R.; Toussaint, D.; Van de Water, R. S.
2012-08-01
We study SU(3)-breaking effects in the neutral Bd-B¯d and Bs-B¯s systems with unquenched Nf=2+1 lattice quantum chromodynamics (QCD). We calculate the relevant matrix elements on the MILC collaboration’s gauge configurations with asqtad-improved staggered sea quarks. For the valence light-quarks (u, d, and s) we use the asqtad action, while for b quarks we use the Fermilab action. We obtain ξ=fBsBBs/fBdBBd=1.268±0.063. We also present results for the ratio of bag parameters BBs/BBd and the ratio of Cabibbo-Kobayashi-Maskawa matrix elements |Vtd|/|Vts|. Although we focus on the calculation of ξ, the strategy and techniques described here will be employed in future extended studies of the B mixing parameters ΔMd,s and ΔΓd,s in the standard model and beyond.
Resonances in Coupled $\pi K\text{-}\eta K$ Scattering from Quantum Chromodynamics
Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.; Wilson, David J.
2014-10-01
Using first-principles calculation within Quantum Chromodynamics, we are able to reproduce the pattern of experimental strange resonances which appear as complex singularities within coupled πK, ηK scattering amplitudes. We make use of numerical computation within the lattice discretized approach to QCD, extracting the energy dependence of scattering amplitudes through their relation- ship to the discrete spectrum of the theory in a finite-volume, which we map out in unprecedented detail.
Mueller, B.
1993-05-15
This report discusses research in the following topics: Hadron structure physics; relativistic heavy ion collisions; finite- temperature QCD; real-time lattice gauge theory; and studies in quantum field theory.
Challenges to quantum chromodynamics: Anomalous spin, heavy quark, and nuclear phenomena
Brodsky, S.J.
1989-11-01
The general structure of QCD meshes remarkably well with the facts of the hadronic world, especially quark-based spectroscopy, current algebra, the approximate point-like structure of large momentum transfer inclusive reactions, and the logarithmic violation of scale invariance in deep inelastic lepton-hadron reactions. QCD has been successful in predicting the features of electron-positron and photon-photon annihilation into hadrons, including the magnitude and scaling of the cross sections, the shape of the photon structure function, the production of hadronic jets with patterns conforming to elementary quark and gluon subprocesses. The experimental measurements appear to be consistent with basic postulates of QCD, that the charge and weak currents within hadrons are carried by fractionally-charged quarks, and that the strength of the interactions between the quarks, and gluons becomes weak at short distances, consistent with asymptotic freedom. Nevertheless in some cases, the predictions of QCD appear to be in dramatic conflict with experiment. The anomalies suggest that the proton itself as a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrival proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trival oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non- negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. 144 refs., 46 figs., 2 tabs.
Lattice Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Sachrajda, C. T.
2016-10-01
I review the the application of the lattice formulation of QCD and large-scale numerical simulations to the evaluation of non-perturbative hadronic effects in Standard Model Phenomenology. I present an introduction to the elements of the calculations and discuss the limitations both in the range of quantities which can be studied and in the precision of the results. I focus particularly on the extraction of the QCD parameters, i.e. the quark masses and the strong coupling constant, and on important quantities in flavour physics. Lattice QCD is playing a central role in quantifying the hadronic effects necessary for the development of precision flavour physics and its use in exploring the limits of the Standard Model and in searches for inconsistencies which would signal the presence of new physics.
Testing quantum chromodynamics
Brodsky, S.J.
1982-09-01
The difficulties in isolating specific QCD mechanisms which control hadronic phenomena, and the complications in obtaining quantitative tests of QCD are discussed. A number of novel QCD effects are reviewed, including heavy quark and higher twist phenomena, initial and final state interactions, direct processes, multiparticle collisions, color filtering, and nuclear target effects. The importance of understanding hadron production at the amplitude level is stressed.
Deta, U. A.; Suparmi,; Cari,; Husein, A. S.; Yuliani, H.; Khaled, I. K. A.; Luqman, H.; Supriyanto
2014-09-30
The Energy Spectra and Wave Function of Schrodinger equation in D-Dimensions for trigonometric Rosen-Morse potential were investigated analytically using Nikiforov-Uvarov method. This potential captures the essential traits of the quark-gluon dynamics of Quantum Chromodynamics. The approximate energy spectra are given in the close form and the corresponding approximate wave function for arbitrary l-state (l ≠ 0) in D-dimensions are formulated in the form of differential polynomials. The wave function of this potential unnormalizable for general case. The wave function of this potential unnormalizable for general case. The existence of extra dimensions (centrifugal factor) and this potential increase the energy spectra of system.
Born's Postulate and Reconstruction of the ψ-Function in Nonrelativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Wiesbrock, H.-W.
1987-12-01
A continuous family of self-adjoint operators is constructed such that their measurement data are insufficient to reproduce uniquely via Born's postulate the underlying quantum state. Moreover, no pair of operators has a common invariant subspace. This rejects a conjecture given by Moroz. On the other hand, strengthening results obtained by Kreinovitch, it is shown that already one special potential and the related localization measurement data at different moments of time can guarantee the uniqueness of reconstruction.
Mueller, B.; Springer, R.P.
1994-05-15
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.
Exclusive processes in quantum chromodynamics
Brodsky, S.J.; Lepage, G.P.
1981-06-01
Large momentum transfer exclusive processes and the short distance structure of hadronic wave functions can be systematically analyzed within the context of perturbative QCD. Predictions for meson form factors, two-photon processes ..gamma gamma.. ..-->.. M anti M, hadronic decays of heavy quark systems, and a number of other related QCD phenomena are reviewed.
Testing quantum chromodynamics in electroproduction
Brodsky, S.J.
1987-05-01
The exclusive channels in electroproduction are discussed. The study of color transparency, the formation zone, and other novel aspects of QCD by measuring exclusive reactions inside nuclear targets is covered. Diffractive electroproduction channels are discussed, and exclusive nuclear processes in QCD are examined. Non-additivity of nuclear structure functions (EMC effect) is also discussed, as well as jet coalescence in electroproduction. (LEW)
Polarization phenomena in quantum chromodynamics
Brodsky, S.J.
1994-03-01
The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and non-perturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g{sub A} on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x{sub bj}; (b) consequences of the principle of hadron helicity retention in high x{sub F} inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. He also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A{sub NN} observed in large angle proton-proton scattering, the anomalously large {rho}{pi} branching ratio of the J/{psi}, and the rapidly changing polarization dependence of both J/{psi} and continuum lepton pair hadroproduction observed at large x{sub F}. The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron.
Antiproton annihilation in quantum chromodynamics
Brodsky, S.J.
1988-10-01
Anti-proton annihilation has a number of important advantages as a probe of QCD in the low energy domain. Exclusive reaction in which complete annihilation of the valance quarks occur. There are a number of exclusive and inclusive /bar p/ reactions in the intermediate momentum transfer domain which provide useful constraints on hadron wavefunctions or test novel features of QCD involving both perturbative and nonperturbative dynamics. Inclusive reactions involving antiprotons have the advantage that the parton distributions are well understood. In these lectures, I will particularly focus on lepton pair production /bar p/A ..-->.. /ell//bar /ell//X as a means to understand specific nuclear features in QCD, including collision broadening, breakdown of the QCD ''target length condition''. Thus studies of low to moderate energy antiproton reactions with laboratory energies under 10 GeV could give further insights into the full structure of QCD. 112 refs., 40 figs.
J/ψ polarization at the Tevatron and the LHC: nonrelativistic-QCD factorization at the crossroads.
Butenschoen, Mathias; Kniehl, Bernd A
2012-04-27
We study the polarization observables of J/ψ hadroproduction at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics. We complete the present knowledge of the relativistic corrections by also providing the contribution due to the intermediate (3)P(J)([8]) color-octet states at this order, which turns out to be quite significant. Exploiting the color-octet long-distance matrix elements previously extracted through a global fit to experimental data of unpolarized J/ψ production, we provide theoretical predictions in the helicity and Collins-Soper frames and compare them with data taken by CDF at Fermilab Tevatron I and II and by ALICE at CERN LHC. The notorious CDF J/ψ polarization anomaly familiar from leading-order analyses persists at the quantum level, while the situation looks promising for the LHC, which is bound to bring final clarification.
Is nonrelativistic gravity possible?
Kocharyan, A. A.
2009-07-15
We study nonrelativistic gravity using the Hamiltonian formalism. For the dynamics of general relativity (relativistic gravity) the formalism is well known and called the Arnowitt-Deser-Misner (ADM) formalism. We show that if the lapse function is constrained correctly, then nonrelativistic gravity is described by a consistent Hamiltonian system. Surprisingly, nonrelativistic gravity can have solutions identical to relativistic gravity ones. In particular, (anti-)de Sitter black holes of Einstein gravity and IR limit of Horava gravity are locally identical.
Casalbuoni, Roberto; Gomis, Joaquim; Longhi, Giorgio
2007-12-15
We construct a classical nonrelativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the noncommutative structure of the model. Under double-dimensional reduction the model reduces to the exotic nonrelativistic particle in 2+1 dimensions.
Holographic thermalization from nonrelativistic branes
NASA Astrophysics Data System (ADS)
Roychowdhury, Dibakar
2016-05-01
In this paper, based on the fundamental principles of gauge/gravity duality and considering a global quench, we probe the physics of thermalization for certain special classes of strongly coupled nonrelativistic quantum field theories that are dual to an asymptotically Schrödinger D p brane space time. In our analysis, we note that during the prelocal stages of the thermal equilibrium the entanglement entropy has a faster growth in time compared to its relativistic cousin. However, it shows a linear growth during the postlocal stages of thermal equilibrium where the so-called tsunami velocity associated with the linear growth of the entanglement entropy saturates to that of its value corresponding to the relativistic scenario. Finally, we explore the saturation region and it turns out that one must constraint certain parameters of the theory in a specific way in order to have discontinuous transitions at the point of saturation.
New approach to nonrelativistic diffeomorphism invariance and its applications
NASA Astrophysics Data System (ADS)
Banerjee, Rabin; Mukherjee, Pradip
2016-04-01
A comprehensive account of a new structured algorithm for obtaining nonrelativistic diffeomorphism invariances in both space and spacetime by gauging the Galilean symmetry in a generic nonrelativistic field theoretical model is provided. Various applications like the obtention of nonrelativistic diffeomorphism invariance, the introduction of the Chern-Simons term and its role in fractional quantum Hall effect, the induction of diffeomorphism in the irrotational fluid model, the abstraction of Newton-Cartan geometry, and the emergence of Horava-Lifshitz gravity are discussed in details.
NASA Astrophysics Data System (ADS)
Yeung, Raymond Yiu-Man
An experiment triggering on single high P _{t} pi^+, pi ^-, K^+, K ^-, p, and p in proton-proton collisions has been performed by the Ames-Bologna-CERN-Dortmund-Heidelberg -Warsaw collaboration using the Split-Field-Magnet detector at the CERN-ISR. The parton model based on Quantum Chromodynamics is compared to the observed events. The single particle inclusive cross sections for centre-of-mass energies up to sqrt{S} = 62 GeV at trigger polar angles theta ~ 45^circ and 90^circ are accurately predicted by the parton model calculations. A programme using the Monte Carlo method to simulate complete events is subsequently developed. The importance sampling technique is applied to enhance the efficiency in the fixed-angle high P_{rm t} trigger. The simulated events are compared to the data. Events triggered by pi^+, pi^-, K^+, and K^- mesons of P_{t} > 4 GeV/c and polar angle theta ~ 45^circ at the highest ISR energy sqrt{S} = 62 GeV are used. Detailed analyses on the transverse and the longitudinal directions of the trigger jet, in addition to the correlations between the trigger and the spectator jets show excellent agreement between the parton model predictions and the data. However, a similar study on the away side demonstrates the necessity of higher-order QCD corrections. Encouraging improvements on the away side are observed when the higher-order QCD corrections are implemented in the parton model using the LLA parton shower formalism. Thus, the effects of higher-order QCD corrections are shown to be important in deep inelastic hadronic processes.
Nonrelativistic scale anomaly, and composite operators with complex scaling dimensions
Moroz, Sergej
2011-05-15
Research Highlights: > Nonrelativistic scale anomaly leads to operators with complex scaling dimensions. > We study an operator O={psi}{psi} in quantum mechanics with 1/r{sup 2} potenial. > The propagator of the composite operator is analytically computed. - Abstract: It is demonstrated that a nonrelativistic quantum scale anomaly manifests itself in the appearance of composite operators with complex scaling dimensions. In particular, we study nonrelativistic quantum mechanics with an inverse square potential and consider a composite s-wave operator O={psi}{psi}. We analytically compute the scaling dimension of this operator and determine the propagator <0|TOO{sup +}|0>. The operator O represents an infinite tower of bound states with a geometric energy spectrum. Operators with higher angular momenta are briefly discussed.
Butenschön, Mathias; Kniehl, Bernd A
2011-01-14
We calculate the cross section of inclusive direct J/ψ hadroproduction at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics, including the full relativistic corrections due to the intermediate 1S(0)[8], 3S(1)[8], and 3P(J)[8] color-octet states. We perform a combined fit of the color-octet long-distance matrix elements to the transverse-momentum (p(T)) distributions measured by CDF at the Fermilab Tevatron and H1 at DESY HERA and demonstrate that they also successfully describe the p(T) distributions from PHENIX at BNL RHIC and CMS at the CERN LHC as well as the photon-proton c.m. energy and (with worse agreement) the inelasticity distributions from H1. This provides a first rigorous test of nonrelativistic QCD factorization at next-to-leading order. In all experiments, the color-octet processes are shown to be indispensable. PMID:21405222
Heavy-quark physics in quantum chromodynamics
Brodsky, S.J.
1991-04-01
Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as {Upsilon} {yields} p{bar p} and B {yields} {pi}{pi}, and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x{sub F} and give anomalous contributions to the quark structure functions of ordinary hadrons at large x{sub bj}. I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/{psi} and {Upsilon} production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x{sub F}, and the coalescence of heavy quarks with co-moving spectators at low x{sub F}.
Windows on the axion. [quantum chromodynamics (QCD)
NASA Technical Reports Server (NTRS)
Turner, Michael S.
1989-01-01
Peccei-Quinn symmetry with attendant axion is a most compelling, and perhaps the most minimal, extension of the standard model, as it provides a very elegant solution to the nagging strong CP-problem associated with the theta vacuum structure of QCD. However, particle physics gives little guidance as to the axion mass; a priori, the plausible values span the range: 10(-12)eV is approx. less than m(a) which is approx. less than 10(6)eV, some 18 orders-of-magnitude. Laboratory experiments have excluded masses greater than 10(4)eV, leaving unprobed some 16 orders-of-magnitude. Axions have a host of interesting astrophysical and cosmological effects, including, modifying the evolution of stars of all types (our sun, red giants, white dwarfs, and neutron stars), contributing significantly to the mass density of the Universe today, and producting detectable line radiation through the decays of relic axions. Consideration of these effects has probed 14 orders-of-magnitude in axion mass, and has left open only two windows for further exploration: 10(-6)eV is approx. less than m(a) is approx. less than 10(-3)eV and 1eV is approx. less than m(a) is approx. less than 5eV (hadronic axions only). Both these windows are accessible to experiment, and a variety of very interesting experiments, all of which involve heavenly axions, are being planned or are underway.
Quantum Chromodynamics and Deep Inelastic Scattering
NASA Astrophysics Data System (ADS)
Ellis, R. Keith
2016-10-01
This article first describes the parton model which was the precursor of the QCD description of hard scattering processes. After the discovery of QCD and asymptotic freedom, the first successful applications were to Deep Inelastic lepton-hadron scattering. The subsequent application of QCD to processes with two initial state hadrons required the understanding and proof of factorization. To take the fledgling theory and turn it into the robust calculational engine it has become today, required a number of technical and conceptual developments which will be described. Prospects for higher loop calculations are also reviewed.
Quark Confinement Physics in Quantum Chromodynamics
NASA Astrophysics Data System (ADS)
Koma, Y.; Suganuma, H.; Amemiya, K.; Fukushima, M.; Toki, H.
2000-01-01
We study abelian dominance and monopole condensation for the quark confinement physics using the lattice QCD simulations in the MA gauge. These phenomena are closely related to the dual superconductor picture of the QCD vacuum, and enable us to construct the dual Ginzburg-Landau (DGL) theory as an useful effective theory of nonperturbative QCD. We then apply the DGL theory to the studies of the low-lying hadron structure and the scalar glueball properties.
Spin effects in perturbative quantum chromodynamics
Brodsky, S.J.; Lepage, G.P.
1980-12-01
The spin dependence of large momentum transfer exclusive and inclusive reactions can be used to test the gluon spin and other basic elements of QCD. In particular, exclusive processes including hadronic decays of heavy quark resonances have the potential of isolating QCD hard scattering subprocesses in situations where the helicities of all the interacting constituents are controlled. The predictions can be summarized in terms of QCD spin selection rules. The calculation of magnetic moment and other hadronic properties in QCD are mentioned.
Janiszewski, Stefan; Karch, Andreas
2013-02-22
We argue that generic nonrelativistic quantum field theories with a holographic description are dual to Hořava gravity. We construct explicit examples of this duality embedded in string theory by starting with relativistic dual pairs and taking a nonrelativistic scaling limit.
Microscopic picture of non-relativistic classicalons
Berkhahn, Felix; Müller, Sophia; Niedermann, Florian; Schneider, Robert E-mail: sophia.x.mueller@physik.uni-muenchen.de E-mail: robert.bob.schneider@physik.uni-muenchen.de
2013-08-01
A theory of a non-relativistic, complex scalar field with derivatively coupled interaction terms is investigated. This toy model is considered as a prototype of a classicalizing theory and in particular of general relativity, for which the black hole constitutes a prominent example of a classicalon. Accordingly, the theory allows for a non-trivial solution of the stationary Gross-Pitaevskii equation corresponding to a black hole in the case of GR. Quantum fluctuations on this classical background are investigated within the Bogoliubov approximation. It turns out that the perturbative approach is invalidated by a high occupation of the Bogoliubov modes. Recently, it was proposed that a black hole is a Bose-Einstein condensate of gravitons that dynamically ensures to stay at the verge of a quantum phase transition. Our result is understood as an indication for that claim. Furthermore, it motivates a non-linear numerical analysis of the model.
Sharkey, Keeper L.; Adamowicz, Ludwik
2014-05-07
An algorithm for quantum-mechanical nonrelativistic variational calculations of L = 0 and M = 0 states of atoms with an arbitrary number of s electrons and with three p electrons have been implemented and tested in the calculations of the ground {sup 4}S state of the nitrogen atom. The spatial part of the wave function is expanded in terms of all-electrons explicitly correlated Gaussian functions with the appropriate pre-exponential Cartesian angular factors for states with the L = 0 and M = 0 symmetry. The algorithm includes formulas for calculating the Hamiltonian and overlap matrix elements, as well as formulas for calculating the analytic energy gradient determined with respect to the Gaussian exponential parameters. The gradient is used in the variational optimization of these parameters. The Hamiltonian used in the approach is obtained by rigorously separating the center-of-mass motion from the laboratory-frame all-particle Hamiltonian, and thus it explicitly depends on the finite mass of the nucleus. With that, the mass effect on the total ground-state energy is determined.
Resonant ${\pi}^{+}\gamma \to {\pi}^{+}{\pi}^{0}$ amplitude from Quantum Chromodynamics
Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Shultz, Christian J.; Thomas, Christopher E.; Wilson, David J.
2015-12-08
We present the first ab initio calculation of a radiative transition of a hadronic resonance within Quantum Chromodynamics (QCD). We compute the amplitude for $\\pi\\pi \\to \\pi\\gamma^\\star$, as a function of the energy of the $\\pi\\pi$ pair and the virtuality of the photon, in the kinematic regime where $\\pi\\pi$ couples strongly to the unstable $\\rho$ resonance. This exploratory calculation is performed using a lattice discretization of QCD with quark masses corresponding to $m_\\pi \\approx 400$ MeV. As a result, we obtain a description of the energy dependence of the transition amplitude, constrained at 48 kinematic points, that we can analytically continue to the $\\rho$ pole and identify from its residue the $\\rho \\to \\pi\\gamma^\\star$ form-factor.
Non-relativistic solar electrons
NASA Technical Reports Server (NTRS)
Lin, R. P.
1974-01-01
Summary of both the direct spacecraft observations of nonrelativistic solar electrons, and observations of the X-ray and radio emission generated by these particles at the sun and in the interplanetary medium. These observations bear on three physical processes basic to energetic particle phenomena: (1) the acceleration of particles in tenuous plasmas; (2) the propagation of energetic charged particles in a disordered magnetic field, and (3) the interaction of energetic charged particles with tenuous plasmas to produce electromagnetic radiation. Because these electrons are frequently accelerated and emitted by the sun, mostly in small and relatively simple flares, it is possible to define a detailed physical picture of these processes. In many small solar flares nonrelativistic electrons accelerated during flash phase constitute the bulk of the total flare energy. Thus the basic flare mechanism in these flares essentially converts the available flare energy into fast electrons. Nonrelativistic electrons exhibit a wide variety of propagation modes in the interplanetary medium, ranging from diffusive to essentially scatter-free. This variability in the propagation may be explained in terms of the distribution of interplanetary magnetic field fluctuations.
Relativistic gravity and parity-violating nonrelativistic effective field theories
NASA Astrophysics Data System (ADS)
Wu, Chaolun; Wu, Shao-Feng
2015-06-01
We show that the relativistic gravity theory can offer a framework to formulate the nonrelativistic effective field theory in a general coordinate invariant way. We focus on the parity violating case in 2 +1 dimensions which is particularly appropriate for the study on quantum Hall effects and chiral superfluids. We discuss how the nonrelativistic spacetime structure emerges from relativistic gravity. We present covariant maps and constraints that relate the field contents in the two theories, which also serve as the holographic dictionary in the context of gauge/gravity duality. A low energy effective action for fractional quantum Hall states is constructed, which captures universal geometric properties and generates nonuniversal corrections systematically. We give another holographic example with dyonic black brane background to calculate thermodynamic and transport properties of strongly coupled nonrelativistic fluids in magnetic field. In particular, by identifying the shift function in the gravity as a minus of guiding center velocity, we obtain the Hall viscosity with its relation to Landau orbital angular momentum density proportional to Wen-Zee shift. Our formalism has a good projection to lowest Landau level.
Torsion and noninertial effects on a nonrelativistic Dirac particle
Bakke, K.
2014-07-15
We investigate torsion and noninertial effects on a spin-1/2 quantum particle in the nonrelativistic limit of the Dirac equation. We consider the cosmic dislocation spacetime as a background and show that a rotating system of reference can be used out to distances which depend on the parameter related to the torsion of the defect. Therefore, we analyse torsion effects on the spectrum of energy of a nonrelativistic Dirac particle confined to a hard-wall potential in a Fermi–Walker reference frame. -- Highlights: •Torsion effects on a spin- 1/2 particle in a noninertial reference frame. •Fermi–Walker reference frame in the cosmic dislocation spacetime background. •Torsion and noninertial effects on the confinement to a hard-wall confining potential.
Non-relativistic scale anomalies
NASA Astrophysics Data System (ADS)
Arav, Igal; Chapman, Shira; Oz, Yaron
2016-06-01
We extend the cohomological analysis in arXiv:1410.5831 of anisotropic Lifshitz scale anomalies. We consider non-relativistic theories with a dynamical critical exponent z = 2 with or without non-relativistic boosts and a particle number symmetry. We distinguish between cases depending on whether the time direction does or does not induce a foliation structure. We analyse both 1 + 1 and 2 + 1 spacetime dimensions. In 1 + 1 dimensions we find no scale anomalies with Galilean boost symmetries. The anomalies in 2 + 1 dimensions with Galilean boosts and a foliation structure are all B-type and are identical to the Lifshitz case in the purely spatial sector. With Galilean boosts and without a foliation structure we find also an A-type scale anomaly. There is an infinite ladder of B-type anomalies in the absence of a foliation structure with or without Galilean boosts. We discuss the relation between the existence of a foliation structure and the causality of the field theory.
Chromodynamic fluctuations in quark-gluon plasma
Mrowczynski, Stanislaw
2008-05-15
Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary, and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.
The Conformal Template and New Perspectives for Quantum Chromodynamics
Brodsky, Stanley J.; /SLAC
2007-03-06
Conformal symmetry provides a systematic approximation to QCD in both its perturbative and nonperturbative domains. One can use the AdS/CFT correspondence between Anti-de Sitter space and conformal gauge theories to obtain an analytically tractable approximation to QCD in the regime where the QCD coupling is large and constant. For example, there is an exact correspondence between the fifth-dimensional coordinate of AdS space and a specific impact variable which measures the separation of the quark constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and allow the computation of exclusive scattering amplitudes. One can also use conformal symmetry as a template for perturbative QCD predictions where the effects of the nonzero beta function can be systematically included in the scale of the QCD coupling. This leads to fixing of the renormalization scale and commensurate scale relations which relate observables without scale or scheme ambiguity. The results are consistent with the renormalization group and the analytic connection of QCD to Abelian theory at N{sub C} {yields} 0. I also discuss a number of novel phenomenological features of QCD. Initial- and .nal-state interactions from gluon-exchange, normally neglected in the parton model, have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, di.ractive hard hadronic reactions, the breakdown of the Lam Tung relation in Drell-Yan reactions, and nuclear shadowing and non-universal antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss tests of hidden color in nuclear wavefunctions, the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency, nonperturbative antisymmetric sea quark distributions, anomalous heavy quark e.ects, and the unexpected effects of direct higher-twist processes.
Quantum chromodynamics and the statistical hydrodynamical model of hadron production
Carruthers, P.; Duong-Van, M.
1983-07-01
We analyze the Fermi-Landau statistical hydrodynamical model of hadron-hadron multiplicities in the framework of QCD, using the Pokorski--Van Hove model wherein the collision of preexisting glue dominates the multiplicity. It is noted that previous dismissal of the possibility of thermalization in the basis of nuclear ''transparency'' is circumvented in this picture because the valence quarks pass through, whereas the gluon clouds interact strongly. Assuming that the gluons equilibrate to a thermalized plasmoid within the Fermi-Landau (FL) Lorentz-contracted initial volume, we derive a simple formula for the multiplicity with the form N/sub ch/roughly-equal2.5 f/sup 1/4/ W/sup 1/2//sub had/ (three flavors excited), where 1-f is the fraction of energy carried away by the leading particles and W/sub had/ = fW is the energy left behind. If f were fixed at a constant value of (1/2), the formula would agree extremely well with data up to and including p-barp collider energies. (The widely held belief that collider multiplicities rule out the Fermi power law was based on the use of W rather than W/sub had/.) However, using the data of Basile et al., in which multiplicities are broken down as a function of W/sub had/ for different W values, we find that the f/sup 1/4/ dependence is ruled out. We conclude that thermalization of the colliding gluon clouds in the FL volume is also ruled out, although thermalization in the gluon fragmentation and central regions remains a possibility.
Quantum chromodynamics and the statistical hydrodynamical model of hadron production
NASA Astrophysics Data System (ADS)
Carruthers, P.; Duong-van, Minh
1983-07-01
We analyze the Fermi-Landau statistical hydrodynamical model of hadron-hadron multiplicities in the framework of QCD, using the Pokorski-Van Hove model wherein the collision of preexisting glue dominates the multiplicity. It is noted that previous dismissal of the possibility of thermalization in the basis of nuclear "transparency" is circumvented in this picture because the valence quarks pass through, whereas the gluon clouds interact strongly. Assuming that the gluons equilibrate to a thermalized plasmoid within the Fermi-Landau (FL) Lorentz-contracted initial volume, we derive a simple formula for the multiplicity with the form Nch~2.5f14Whad12 (three flavors excited), where 1-f is the fraction of energy carried away by the leading particles and Whad=fW is the energy left behind. If f were fixed at a constant value of 1/2 , the formula would agree extremely well with data up to and including p¯p collider energies. (The widely held belief that collider multiplicities rule out the Fermi power law was based on the use of W rather than Whad.) However, using the data of Basile et al., in which multiplicities are broken down as a function of Whad for different W values, we find that the f14 dependence is ruled out. We conclude that thermalization of the colliding gluon clouds in the FL volume is also ruled out, although thermalization in the gluon fragmentation and central regions remains a possibility.
Two-photon exclusive processes in quantum chromodynamics
Brodsky, S.J.
1986-07-01
QCD predictions for ..gamma gamma.. annihilation into single mesons, meson pairs, and baryon pairs are reviewed. Two-photon exclusive processes provide the most sensitive and practical measure of the distribution amplitudes, and thus a critical confrontation between QCD and experiment. Both the angular distribution and virtual photon mass dependence of these amplitudes are sensitive to the shapes of the phi (chi, Q). Novel effects involving the production of qq anti q anti q states at threshold are also discussed, and a new method is presented for systematically incorporating higher-order QCD corrections in ..gamma gamma.. reactions.
Zero temperature string breaking in lattice quantum chromodynamics
Bernard, Claude; DeGrand, Thomas; DeTar, Carleton; Lacock, Pierre; Gottlieb, Steven; Heller, Urs M.; Hetrick, James; Orginos, Kostas; Toussaint, Doug; Sugar, Robert L.
2001-10-01
The separation of a heavy quark and antiquark pair leads to the formation of a tube of flux, or ''string,'' which should break in the presence of light quark-antiquark pairs. This expected zero-temperature phenomenon has proven elusive in simulations of lattice QCD. We study mixing between the string state and the two-meson decay channel in QCD with two flavors of dynamical sea quarks. We confirm that mixing is weak and find that it decreases at level crossing. While our study does not show direct effects of internal quark loops, our results, combined with unitarity, give a clear confirmation of string breaking.
Tests of quantum chromodynamics in exclusive and inclusive electroproduction
Brodsky, S.J.
1989-06-01
This paper discusses the following topics: overview of electroproduction phenomenology; hadronization of the quark and spectator systems; hadronization in nuclei; shadowing and anti- shadowing; color transparency; exclusive channels in electroproduction; hadronic wavefunction phenomenology; diffractive electroproduction; exclusive nuclear processes in QCD; and relation of electroproduction to QCD wavefunctions. 58 refs., 22 figs. (LSP)
Inclusive and Exclusive Compton Processes in Quantum Chromodynamics
Ales Psaker
2005-12-31
In our work, we describe two types of Compton processes. As an example of an inclusive process, we consider the high-energy photoproduction of massive muon pairs off the nucleon. We analyze the process in the framework of the QCD parton model, in which the usual parton distributions emerge as a tool to describe the nucleon in terms of quark and gluonic degrees of freedom. To study its exclusive version, a new class of phenomenological functions is required, namely, generalized parton distributions. They can be considered as a generalization of the usual parton distributions measured in deeply inelastic lepton-nucleon scattering. Generalized parton distributions (GPDs) may be observed in hard exclusive reactions such as deeply virtual Compton scattering. We develop an extension of this particular process into the weak interaction sector. We also investigate a possible application of the GPD formalism to wide-angle real Compton scattering.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and ^{3}He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m_{π} ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of ^{3}He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures its dominant structure. Similarly a shell-model-like moment is found for the triton, μ_{3H} ~ μ_{p}. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.
Magnetic moments of light nuclei from lattice quantum chromodynamics
Beane, S. R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H. W.; Orginos, K.; Parreño, A.; Savage, M. J.; Tiburzi, B. C.
2014-12-16
We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to mπ ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures itsmore » dominant structure. Similarly a shell-model-like moment is found for the triton, μ3H ~ μp. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.« less
Quantum simulations of lattice gauge theories using ultracold atoms in optical lattices
NASA Astrophysics Data System (ADS)
Zohar, Erez; Cirac, J. Ignacio; Reznik, Benni
2016-01-01
Can high-energy physics be simulated by low-energy, non-relativistic, many-body systems such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in particular, they manifest neither local gauge invariance nor Lorentz invariance, which are crucial properties of the quantum field theories which are the building blocks of the standard model of elementary particles. However, it turns out, surprisingly, that there are ways to configure an atomic system to manifest both local gauge invariance and Lorentz invariance. In particular, local gauge invariance can arise either as an effective low-energy symmetry, or as an exact symmetry, following from the conservation laws in atomic interactions. Hence, one could hope that such quantum simulators may lead to a new type of (table-top) experiments which will be used to study various QCD (quantum chromodynamics) phenomena, such as the confinement of dynamical quarks, phase transitions and other effects, which are inaccessible using the currently known computational methods. In this report, we review the Hamiltonian formulation of lattice gauge theories, and then describe our recent progress in constructing the quantum simulation of Abelian and non-Abelian lattice gauge theories in 1 + 1 and 2 + 1 dimensions using ultracold atoms in optical lattices.
Quantum simulations of lattice gauge theories using ultracold atoms in optical lattices.
Zohar, Erez; Cirac, J Ignacio; Reznik, Benni
2016-01-01
Can high-energy physics be simulated by low-energy, non-relativistic, many-body systems such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in particular, they manifest neither local gauge invariance nor Lorentz invariance, which are crucial properties of the quantum field theories which are the building blocks of the standard model of elementary particles. However, it turns out, surprisingly, that there are ways to configure an atomic system to manifest both local gauge invariance and Lorentz invariance. In particular, local gauge invariance can arise either as an effective low-energy symmetry, or as an exact symmetry, following from the conservation laws in atomic interactions. Hence, one could hope that such quantum simulators may lead to a new type of (table-top) experiments which will be used to study various QCD (quantum chromodynamics) phenomena, such as the confinement of dynamical quarks, phase transitions and other effects, which are inaccessible using the currently known computational methods. In this report, we review the Hamiltonian formulation of lattice gauge theories, and then describe our recent progress in constructing the quantum simulation of Abelian and non-Abelian lattice gauge theories in 1 + 1 and 2 + 1 dimensions using ultracold atoms in optical lattices. PMID:26684222
Bottomonium above Deconfinement in Lattice Nonrelativistic QCD
Aarts, G.; Kim, S.; Lombardo, M. P.; Oktay, M. B.; Ryan, S. M.; Sinclair, D. K.; Skullerud, J.-I.
2011-02-11
We study the temperature dependence of bottomonium for temperatures in the range 0.4T{sub c}
Cascading Multicriticality in Nonrelativistic Spontaneous Symmetry Breaking
NASA Astrophysics Data System (ADS)
Griffin, Tom; Grosvenor, Kevin T.; Hořava, Petr; Yan, Ziqi
2015-12-01
Without Lorentz invariance, spontaneous global symmetry breaking can lead to multicritical Nambu-Goldstone modes with a higher-order low-energy dispersion ω ˜kn (n =2 ,3 ,… ), whose naturalness is protected by polynomial shift symmetries. Here, we investigate the role of infrared divergences and the nonrelativistic generalization of the Coleman-Hohenberg-Mermin-Wagner (CHMW) theorem. We find novel cascading phenomena with large hierarchies between the scales at which the value of n changes, leading to an evasion of the "no-go" consequences of the relativistic CHMW theorem.
New approach to nonrelativistic ideal magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Banerjee, Rabin; Kumar, Kuldeep
2016-07-01
We provide a novel action principle for nonrelativistic ideal magnetohydrodynamics in the Eulerian scheme exploiting a Clebsch-type parametrisation. Both Lagrangian and Hamiltonian formulations have been considered. Within the Hamiltonian framework, two complementary approaches have been discussed using Dirac's constraint analysis. In one case the Hamiltonian is canonical involving only physical variables but the brackets have a noncanonical structure, while the other retains the canonical structure of brackets by enlarging the phase space. The special case of incompressible magnetohydrodynamics is also considered where, again, both the approaches are discussed in the Hamiltonian framework. The conservation of the stress tensor reveals interesting aspects of the theory.
Non-relativistic fields from arbitrary contracting backgrounds
NASA Astrophysics Data System (ADS)
Bergshoeff, Eric; Rosseel, Jan; Zojer, Thomas
2016-09-01
We discuss a non-relativistic contraction of massive and massless field theories minimally coupled to gravity. Using the non-relativistic limiting procedure introduced in our previous work, we (re-)derive non-relativistic field theories of massive and massless spins 0 to 3/2 coupled to torsionless Newton–Cartan backgrounds. We elucidate the relativistic origin of the Newton–Cartan central charge gauge field {m}μ and explain its relation to particle number conservation.
Non-relativistic fields from arbitrary contracting backgrounds
NASA Astrophysics Data System (ADS)
Bergshoeff, Eric; Rosseel, Jan; Zojer, Thomas
2016-09-01
We discuss a non-relativistic contraction of massive and massless field theories minimally coupled to gravity. Using the non-relativistic limiting procedure introduced in our previous work, we (re-)derive non-relativistic field theories of massive and massless spins 0 to 3/2 coupled to torsionless Newton-Cartan backgrounds. We elucidate the relativistic origin of the Newton-Cartan central charge gauge field {m}μ and explain its relation to particle number conservation.
Nuclear chromodynamics is not the colorization of nuclear physics
Sivers, D.
1988-07-19
The successful description of nuclei in terms of nucleons, deltas and mesons provides an enormous challenge to QCD. It compels us to pursue our theoretical understanding of chromodynamics into the realm of multiple color singlets in order to examine the concept of color saturation. To pursue this theme, we examine the idea of nuclear transparency in the light of models for confinement and describe the formulation of lattice simulations sensitive to exchange forces. 22 refs., 7 figs.
GRB afterglows in the nonrelativistic phase
NASA Astrophysics Data System (ADS)
Huang, Y. F.; Lu, T.
2008-10-01
When discussing the afterglows of gamma-ray bursts analytically, it is usually assumed that the external shock is always ultra-relativisitc, with the bulk Lorentz factor much larger than 1. However, we show that the deceleration of the external shock is actually very quick. The afterglow may typically enter the nonrelativistic phase in several days to teens of days, and may even enter the deep Newtonian phase in tens of days to several months. One thus should be careful in using those familiar analytical expressions that are derived only under the ultra-relativistic assumption. To explain the observed afterglows that typically last for a few weeks to several months, we need to consider the dynamics and radiation in the nonrelativisitic phase.
Symmetries of nonrelativistic phase space and the structure of quark-lepton generation
NASA Astrophysics Data System (ADS)
Źenczykowski, Piotr
2009-06-01
According to the Hamiltonian formalism, nonrelativistic phase space may be considered as an arena of physics, with momentum and position treated as independent variables. Invariance of x2 + p2 constitutes then a natural generalization of ordinary rotational invariance. We consider Dirac-like linearization of this form, with position and momentum satisfying standard commutation relations. This leads to the identification of a quantum-level structure from which some phase space properties might emerge. Genuine rotations and reflections in phase space are tied to the existence of new quantum numbers, unrelated to ordinary 3D space. Their properties allow their identification with the internal quantum numbers characterising the structure of a single quark-lepton generation in the Standard Model. In particular, the algebraic structure of the Harari-Shupe preon model of fundamental particles is reproduced exactly and without invoking any subparticles. Analysis of the Clifford algebra of nonrelativistic phase space singles out an element which might be associated with the concept of lepton mass. This element is transformed into a corresponding element for a single coloured quark, leading to a generalization of the concept of mass and a different starting point for the discussion of quark unobservability.
The Harari Shupe preon model and nonrelativistic quantum phase space
NASA Astrophysics Data System (ADS)
Żenczykowski, P.
2008-03-01
We propose that the whole algebraic structure of the Harari-Shupe rishon model originates via a Dirac-like linearization of quadratic form x2 +p2, with position and momentum satisfying standard commutation relations. The scheme does not invoke the concept of preons as spin-1/2 subparticles, thus evading the problem of preon confinement, while fully explaining all symmetries emboded in the Harari-Shupe model. Furthermore, the concept of quark colour is naturally linked to the ordering of rishons. Our scheme leads to group U (1) ⊗ SU (3) combined with SU (2), with two of the SU (2) generators not commuting with reflections. An interpretation of intra-generation quark-lepton transformations in terms of genuine rotations and reflections in phase space is proposed.
Ab initio non-relativistic spin dynamics
Ding, Feizhi; Goings, Joshua J.; Li, Xiaosong; Frisch, Michael J.
2014-12-07
Many magnetic materials do not conform to the (anti-)ferromagnetic paradigm where all electronic spins are aligned to a global magnetization axis. Unfortunately, most electronic structure methods cannot describe such materials with noncollinear electron spin on account of formally requiring spin alignment. To overcome this limitation, it is necessary to generalize electronic structure methods and allow each electron spin to rotate freely. Here, we report the development of an ab initio time-dependent non-relativistic two-component spinor (TDN2C), which is a generalization of the time-dependent Hartree-Fock equations. Propagating the TDN2C equations in the time domain allows for the first-principles description of spin dynamics. A numerical tool based on the Hirshfeld partitioning scheme is developed to analyze the time-dependent spin magnetization. In this work, we also introduce the coupling between electron spin and a homogenous magnetic field into the TDN2C framework to simulate the response of the electronic spin degrees of freedom to an external magnetic field. This is illustrated for several model systems, including the spin-frustrated Li{sub 3} molecule. Exact agreement is found between numerical and analytic results for Larmor precession of hydrogen and lithium atoms. The TDN2C method paves the way for the ab initio description of molecular spin transport and spintronics in the time domain.
Ab initio non-relativistic spin dynamics
NASA Astrophysics Data System (ADS)
Ding, Feizhi; Goings, Joshua J.; Frisch, Michael J.; Li, Xiaosong
2014-12-01
Many magnetic materials do not conform to the (anti-)ferromagnetic paradigm where all electronic spins are aligned to a global magnetization axis. Unfortunately, most electronic structure methods cannot describe such materials with noncollinear electron spin on account of formally requiring spin alignment. To overcome this limitation, it is necessary to generalize electronic structure methods and allow each electron spin to rotate freely. Here, we report the development of an ab initio time-dependent non-relativistic two-component spinor (TDN2C), which is a generalization of the time-dependent Hartree-Fock equations. Propagating the TDN2C equations in the time domain allows for the first-principles description of spin dynamics. A numerical tool based on the Hirshfeld partitioning scheme is developed to analyze the time-dependent spin magnetization. In this work, we also introduce the coupling between electron spin and a homogenous magnetic field into the TDN2C framework to simulate the response of the electronic spin degrees of freedom to an external magnetic field. This is illustrated for several model systems, including the spin-frustrated Li3 molecule. Exact agreement is found between numerical and analytic results for Larmor precession of hydrogen and lithium atoms. The TDN2C method paves the way for the ab initio description of molecular spin transport and spintronics in the time domain.
Topics in nuclear chromodynamics: Color transparency and hadronization in the nucleus
Brodsky, S.J.
1988-03-01
The nucleus plays two complimentary roles in quantum chromodynamics: (1) A nuclear target can be used as a control medium or background field to modify or probe quark and gluon subprocesses. Some novel examples are color transparency, the predicted transparency of the nucleus to hadrons participating in high momentum transfer exclusive reactions, and formation zone phenomena, the absence of hard, collinear, target-induced radiation by a quark or gluon interacting in a high momentum transfer inclusive reaction if its energy is large compared to a scale proportional to the length of the target. (Soft radiation and elastic initial state interactions in the nucleus still occur.) Coalescence with co-moving spectators is discussed as a mechanism which can lead to increased open charm hadroproduction, but which also suppresses forward charmonium production (relative to lepton pairs) in heavy ion collisions. Also discussed are some novel features of nuclear diffractive amplitudes--high energy hadronic or electromagnetic reactions which leave the entire nucleus intact and give nonadditive contributions to the nuclear structure function at low /kappa cur//sub Bj/. (2) Conversely, the nucleus can be studied as a QCD structure. At short distances, nuclear wave functions and nuclear interactions necessarily involve hidden color, degrees of freedom orthogonal to the channels described by the usual nucleon or isobar degrees of freedom. At asymptotic momentum transfer, the deuteron form factor and distribution amplitude are rigorously calculable. One can also derive new types of testable scaling laws for exclusive nuclear amplitudes in terms of the reduced amplitude formalism.
Correspondence between asymptotically flat spacetimes and nonrelativistic conformal field theories.
Bagchi, Arjun
2010-10-22
We find a surprising connection between asymptotically flat spacetimes and nonrelativistic conformal systems in one lower dimension. The Bondi-Metzner-Sachs (BMS) group is the group of asymptotic isometries of flat Minkowski space at null infinity. This is known to be infinite dimensional in three and four dimensions. We show that the BMS algebra in 3 dimensions is the same as the 2D Galilean conformal algebra (GCA) which is of relevance to nonrelativistic conformal symmetries. We further justify our proposal by looking at a Penrose limit on a radially infalling null ray inspired by nonrelativistic scaling and obtain a flat metric. The BMS4 algebra is also discussed and found to be the same as another class of GCA, called semi-GCA, in three dimensions. We propose a general BMS-GCA correspondence. Some consequences are discussed. PMID:21231033
Correspondence between Asymptotically Flat Spacetimes and Nonrelativistic Conformal Field Theories
Bagchi, Arjun
2010-10-22
We find a surprising connection between asymptotically flat spacetimes and nonrelativistic conformal systems in one lower dimension. The Bondi-Metzner-Sachs (BMS) group is the group of asymptotic isometries of flat Minkowski space at null infinity. This is known to be infinite dimensional in three and four dimensions. We show that the BMS algebra in 3 dimensions is the same as the 2D Galilean conformal algebra (GCA) which is of relevance to nonrelativistic conformal symmetries. We further justify our proposal by looking at a Penrose limit on a radially infalling null ray inspired by nonrelativistic scaling and obtain a flat metric. The BMS{sub 4} algebra is also discussed and found to be the same as another class of GCA, called semi-GCA, in three dimensions. We propose a general BMS-GCA correspondence. Some consequences are discussed.
Nonrelativistic approaches derived from point-coupling relativistic models
Lourenco, O.; Dutra, M.; Delfino, A.; Sa Martins, J. S.
2010-03-15
We construct nonrelativistic versions of relativistic nonlinear hadronic point-coupling models, based on new normalized spinor wave functions after small component reduction. These expansions give us energy density functionals that can be compared to their relativistic counterparts. We show that the agreement between the nonrelativistic limit approach and the Skyrme parametrizations becomes strongly dependent on the incompressibility of each model. We also show that the particular case A=B=0 (Walecka model) leads to the same energy density functional of the Skyrme parametrizations SV and ZR2, while the truncation scheme, up to order {rho}{sup 3}, leads to parametrizations for which {sigma}=1.
Nonrelativistic equations of motion for particles with arbitrary spin
Fushchich, V.I.; Nikitin, A.G.
1981-09-01
First- and second-order Galileo-invariant systems of differential equations which describe the motion of nonrelativistic particles of arbitrary spin are derived. The equations can be derived from a Lagrangian and describe the dipole, quadrupole, and spin-orbit interaction of the particles with an external field; these interactions have traditionally been regarded as purely relativistic effects. The problem of the motion of a nonrelativistic particle of arbitrary spin in a homogeneous magnetic field is solved exactly on the basis of the obtained equations. The generators of all classes of irreducible representations of the Galileo group are found.
The quantum measurement of time
NASA Technical Reports Server (NTRS)
Shepard, Scott R.
1994-01-01
Traditionally, in non-relativistic Quantum Mechanics, time is considered to be a parameter, rather than an observable quantity like space. In relativistic Quantum Field Theory, space and time are treated equally by reducing space to also be a parameter. Herein, after a brief review of other measurements, we describe a third possibility, which is to treat time as a directly observable quantity.
Quantum physics without quantum philosophy
NASA Astrophysics Data System (ADS)
Dürr, Detlef; Goldstein, Sheldon; Zanghì, Nino
Quantum philosophy, a peculiar twentieth-century malady, is responsible for most of the conceptual muddle plaguing the foundations of quantum physics. When this philosophy is eschewed, one naturally arrives at Bohmian mechanics, which is what emerges from Schrödinger's equation for a nonrelativistic system of particles when we merely insist that 'particles' means particles. While distinctly non-Newtonian, Bohmian mechanics is a fully deterministic theory of particles in motion, a motion choreographed by the wave function. The quantum formalism emerges when measurement situations are analyzed according to this theory. When the quantum formalism is regarded as arising in this way, the paradoxes and perplexities so often associated with quantum theory simply evaporate.
Renormalization group analysis in nonrelativistic QCD for colored scalars
Hoang, Andre H.; Ruiz-Femenia, Pedro
2006-01-01
The velocity nonrelativistic QCD Lagrangian for colored heavy scalar fields in the fundamental representation of QCD and the renormalization group analysis of the corresponding operators are presented. The results are an important ingredient for renormalization group improved computations of scalar-antiscalar bound state energies and production rates at next-to-next-to-leading-logarithmic (NNLL) order.
Gauging nonrelativistic field theories using the coset construction
NASA Astrophysics Data System (ADS)
Karananas, Georgios K.; Monin, Alexander
2016-03-01
We discuss how nonrelativistic spacetime symmetries can be gauged in the context of the coset construction. We consider theories invariant under the centrally extended Galilei algebra as well as the Lifshitz one, and we investigate under what conditions they can be supplemented by scale transformations. We also clarify the role of torsion in these theories.
Exact nonrelativistic polarizabilities of the hydrogen atom with the Lagrange-mesh method
NASA Astrophysics Data System (ADS)
Baye, Daniel
2012-12-01
Exact analytical expressions of the dipole polarizabilities of the nonrelativistic hydrogen atom in spherical coordinates are derived with the help of the Lagrange-mesh numerical method. This method can provide exact energies and wave functions for well-chosen conditions of calculation. Exact dipole polarizabilities are obtained after an unambiguous rounding up to at least principal quantum numbers around n=30. The scalar polarizability of any nl level is given by n4[4n2+14+7l(l+1)]/4 and its tensor polarizability is given by -n4[3n2-9+11l(l+1)]l/4(2l+3), which allows the calculation of the polarizability of any hydrogen state nlm.
Filamentation instability in a quantum magnetized plasma
Bret, A.
2008-02-15
The filamentation instability occurring when a nonrelativistic electron beam passes through a quantum magnetized plasma is investigated by means of a cold quantum magnetohydrodynamic model. It is proved that the instability can be completely suppressed by quantum effects if and only if a finite magnetic field is present. A dimensionless parameter is identified that measures the strength of quantum effects. Strong quantum effects allow for a much smaller magnetic field to suppress the instability than in the classical regime.
Holography of Non-relativistic String on AdS{sub 5}xS{sup 5}
Sakaguchi, Makoto; Yoshida, Kentaroh
2008-11-23
We review a holography of a non-relativistic (NR) string on AdS{sub 5}xS{sup 5}. The NR string can be regarded as a semiclassical string around an AdS{sub 2} classical solution, which corresponds to a straight Wilson line in the gauge-theory side. Non-normalizable modes of the NR string correspond to string fluctuations reaching the boundary, and cause small deformations of the Wilson line. The operator inserted on the Wilson line are found from the small deformation of the Wilson line. Normalizable modes, which exist in the Lorentzian case, are considered as wave functions in a conformal quantum mechanics.
Nonrelativistic approach for cosmological scalar field dark matter
NASA Astrophysics Data System (ADS)
Ureña-López, L. Arturo
2014-07-01
We derive nonrelativistic equations of motion for the formation of cosmological structure in a scalar field dark matter (SFDM) model corresponding to a complex scalar field endowed with a quadratic scalar potential. Starting with the equations of motion written in the Newtonian gauge of scalar perturbations, we separate out the involved fields into relativistic and nonrelativistic parts and find the equations of motion for the latter that can be used to build up the full solution. One important assumption will be that the SFDM field is in the regime of fast oscillations, under which its behavior in the homogeneous regime is exactly that of cold dark matter. The resultant equations are quite similar to the Schrödinger-Poisson system of Newtonian boson stars plus relativistic leftovers, and they can be used to study the formation of cosmological structure in SFDM models, and others alike, to ultimately prove their viability as complete dark matter models.
The nonrelativistic limit of the relativistic point coupling model
NASA Astrophysics Data System (ADS)
Sulaksono, A.; Bürvenich, T.; Maruhn, J. A.; Reinhard, P.-G.; Greiner, W.
2003-11-01
We relate the relativistic finite range mean-field model (RMF-FR) to the point-coupling variant and compare the nonlinear density dependence. From this, the effective Hamiltonian of the nonlinear point-coupling model in the nonrelativistic limit is derived. Different from the nonrelativistic models, the nonlinearity in the relativistic models automatically yields contributions in the form of a weak density dependence not only in the central potential but also in the spin-orbit potential. The central potential affects the bulk and surface properties while the spin-orbit potential is crucial for the shell structure of finite nuclei. A modification in the Skyrme-Hartree-Fock model with a density-dependent spin-orbit potential inspired by the point-coupling model is suggested.
Non-Relativistic Twistor Theory and Newton-Cartan Geometry
NASA Astrophysics Data System (ADS)
Dunajski, Maciej; Gundry, James
2016-03-01
We develop a non-relativistic twistor theory, in which Newton-Cartan structures of Newtonian gravity correspond to complex three-manifolds with a four-parameter family of rational curves with normal bundle O oplus O(2)}. We show that the Newton-Cartan space-times are unstable under the general Kodaira deformation of the twistor complex structure. The Newton-Cartan connections can nevertheless be reconstructed from Merkulov's generalisation of the Kodaira map augmented by a choice of a holomorphic line bundle over the twistor space trivial on twistor lines. The Coriolis force may be incorporated by holomorphic vector bundles, which in general are non-trivial on twistor lines. The resulting geometries agree with non-relativistic limits of anti-self-dual gravitational instantons.
Communication: Quantum mechanics without wavefunctions
Schiff, Jeremy; Poirier, Bill
2012-01-21
We present a self-contained formulation of spin-free non-relativistic quantum mechanics that makes no use of wavefunctions or complex amplitudes of any kind. Quantum states are represented as ensembles of real-valued quantum trajectories, obtained by extremizing an action and satisfying energy conservation. The theory applies for arbitrary configuration spaces and system dimensionalities. Various beneficial ramifications--theoretical, computational, and interpretational--are discussed.
Curved non-relativistic spacetimes, Newtonian gravitation and massive matter
Geracie, Michael Prabhu, Kartik Roberts, Matthew M.
2015-10-15
There is significant recent work on coupling matter to Newton-Cartan spacetimes with the aim of investigating certain condensed matter phenomena. To this end, one needs to have a completely general spacetime consistent with local non-relativistic symmetries which supports massive matter fields. In particular, one cannot impose a priori restrictions on the geometric data if one wants to analyze matter response to a perturbed geometry. In this paper, we construct such a Bargmann spacetime in complete generality without any prior restrictions on the fields specifying the geometry. The resulting spacetime structure includes the familiar Newton-Cartan structure with an additional gauge field which couples to mass. We illustrate the matter coupling with a few examples. The general spacetime we construct also includes as a special case the covariant description of Newtonian gravity, which has been thoroughly investigated in previous works. We also show how our Bargmann spacetimes arise from a suitable non-relativistic limit of Lorentzian spacetimes. In a companion paper [M. Geracie et al., e-print http://arxiv.org/abs/1503.02680 ], we use this Bargmann spacetime structure to investigate the details of matter couplings, including the Noether-Ward identities, and transport phenomena and thermodynamics of non-relativistic fluids.
OPE convergence in non-relativistic conformal field theories
NASA Astrophysics Data System (ADS)
Goldberger, Walter D.; Khandker, Zuhair U.; Prabhu, Siddharth
2015-12-01
Motivated by applications to the study of ultracold atomic gases near the unitarity limit, we investigate the structure of the operator product expansion (OPE) in non-relativistic conformal field theories (NRCFTs). The main tool used in our analysis is the representation theory of charged (i.e. non-zero particle number) operators in the NR-CFT, in particular the mapping between operators and states in a non-relativistic "radial quantization" Hilbert space. Our results include: a determination of the OPE coefficients of descendant operators in terms of those of the underlying primary state, a demonstration of convergence of the (imaginary time) OPE in certain kinematic limits, and an estimate of the decay rate of the OPE tail inside matrix elements which, as in relativistic CFTs, depends exponentially on operator dimensions. To illustrate our results we consider several examples, including a strongly interacting field theory of bosons tuned to the unitarity limit, as well as a class of holographic models. Given the similarity with known statements about the OPE in SO(2, d) invariant field theories, our results suggest the existence of a bootstrap approach to constraining NRCFTs, with applications to bound state spectra and interactions. We briefly comment on a possible implementation of this non-relativistic conformal bootstrap program.
On the dynamics of non-relativistic flavor-mixed particles
Medvedev, Mikhail V.
2014-06-01
Evolution of a system of interacting non-relativistic quantum flavor-mixed particles is considered both theoretically and numerically. It was shown that collisions of mixed particles not only scatter them elastically, but can also change their mass eigenstates thus affecting particles' flavor composition and kinetic energy. The mass eigenstate conversions and elastic scattering are related but different processes, hence the conversion S-matrix elements can be arbitrarily large even when the elastic scattering S-matrix elements vanish. The conversions are efficient when the mass eigenstates are well-separated in space but suppressed if their wave-packets overlap; the suppression is most severe for mass-degenerate eigenstates in flat space-time. The mass eigenstate conversions can lead to an interesting process, called ''quantum evaporation'', in which mixed particles, initially confined deep inside a gravitational potential well and scattering only off each other, can escape from it without extra energy supply leaving nothing behind inside the potential at t → ∞. Implications for the cosmic neutrino background and the two-component dark matter model are discussed and a prediction for the direct detection dark matter experiments is made.
Ball lightning with the nonrelativistic electrons of the core
NASA Astrophysics Data System (ADS)
Shmatov, M. L.
2015-08-01
The lifetimes, volume densities of energy, electron and ion densities and other parameters of ball lightning cores with the nonrelativistic electrons are estimated. The model according to which the motion of the electrons of the ball lightning core is the superposition of the oscillatory motion and the thermal motion in the directions perpendicular to those of the oscillations is proposed. Some problems related to isolation of the ball lightning core from the atmosphere and the transfer of the atmospheric pressure on it are considered.
Electroweak absorptive parts in the matching conditions of nonrelativistic QCD
Hoang, Andre H.; Reisser, Christoph J.
2005-04-01
Electroweak corrections associated with the instability of the top quark to the next-to-next-to-leading logarithmic (NNLL) total top pair threshold cross section in e{sup +}e{sup -} annihilation are determined. Our method is based on absorptive parts in electroweak matching conditions of the operators of nonrelativistic QCD and the optical theorem. The corrections lead to ultraviolet phase space divergences that have to be renormalized and lead to NLL mixing effects. Numerically, the corrections can amount to several percent and are comparable to the known NNLL QCD corrections.
Conservation of energy and momentum in nonrelativistic plasmas
Sugama, H.; Watanabe, T.-H.; Nunami, M.
2013-02-15
Conservation laws of energy and momentum for nonrelativistic plasmas are derived from applying Noether's theorem to the action integral for the Vlasov-Poisson-Ampere system [Sugama, Phys. Plasmas 7, 466 (2000)]. The symmetric pressure tensor is obtained from modifying the asymmetric canonical pressure tensor with using the rotational symmetry of the action integral. Differences between the resultant conservation laws and those for the Vlasov-Maxwell system including the Maxwell displacement current are clarified. These results provide a useful basis for gyrokinetic conservation laws because gyrokinetic equations are derived as an approximation of the Vlasov-Poisson-Ampere system.
Extended Klein-Gordon action, gravity and nonrelativistic fluid
Hassaiene, Mokhtar
2006-03-15
We consider a scalar field action for which the Lagrangian density is a power of the massless Klein-Gordon Lagrangian. The coupling of gravity to this matter action is considered. In this case, we show the existence of nontrivial scalar field configurations with vanishing energy-momentum tensor on any static, spherically symmetric vacuum solutions of the Einstein equations. These configurations in spite of being coupled to gravity do not affect the curvature of space-time. The properties of this particular matter action are also analyzed. For a particular value of the exponent, the extended Klein-Gordon action is shown to exhibit a conformal invariance without requiring the introduction of a nonminimal coupling. We also establish a correspondence between this action and a nonrelativistic isentropic fluid in one fewer dimension. This fluid can be identified with the (generalized) Chaplygin gas for a particular value of the power. It is also shown that the nonrelativistic fluid admits, apart from the Galileo symmetry, an additional symmetry whose action is a rescaling of the time.
Bivelocity Picture in the Nonrelativistic Limit of Relativistic Hydrodynamics
NASA Astrophysics Data System (ADS)
Koide, Tomoi; Ramos, Rudnei O.; Vicente, Gustavo S.
2015-02-01
We discuss the nonrelativistic limit of the relativistic Navier-Fourier-Stokes (NFS) theory. The next-to-leading order relativistic corrections to the NFS theory for the Landau-Lifshitz fluid are obtained. While the lowest order truncation of the velocity expansion leads to the usual NFS equations of nonrelativistic fluids, we show that when the next-to-leading order relativistic corrections are included, the equations can be expressed concurrently with two different fluid velocities. One of the fluid velocities is parallel to the conserved charge current (which follows the Eckart definition) and the other one is parallel to the energy current (which follows the Landau-Lifshitz definition). We compare this next-to-leading order relativistic hydrodynamics with bivelocity hydrodynamics, which is one of the generalizations of the NFS theory and is formulated in such a way to include the usual mass velocity and also a new velocity, called the volume velocity. We find that the volume velocity can be identified with the velocity obtained in the Landau-Lifshitz definition. Then, the structure of bivelocity hydrodynamics, which is derived using various nontrivial assumptions, is reproduced in the NFS theory including the next-to-leading order relativistic corrections.
Experimental results on QCD (Quantum Chromodynamics) from e/sup +/e/sup -/ annihilation
de Boer, W.
1987-09-01
A review is given on QCD results from studying e/sup +/e/sup -/ annihilation with the PEP and PETRA storage rings with special emphasis on jet physics and the determination of the strong coupling constant ..cap alpha../sub s/. 92 refs., 28 figs., 3 tabs.
Asymptotic freedom in the front-form Hamiltonian for quantum chromodynamics of gluons
NASA Astrophysics Data System (ADS)
Gómez-Rocha, María; Głazek, Stanisław D.
2015-09-01
Asymptotic freedom of gluons in pure-gauge QCD is obtained in the leading terms of their renormalized Hamiltonian in the Fock space, instead of considering virtual Green's functions or scattering amplitudes. Namely, we calculate the three-gluon interaction term in the effective front-form Hamiltonian for gluons in the Minkowski space-time using the renormalization group procedure for effective particles (RGPEP), with a new generator. The resulting three-gluon vertex is a function of the scale parameter, s , that has an interpretation of the size of effective gluons. The corresponding Hamiltonian running coupling constant, gλ, depending on the associated momentum scale λ =1 /s , is calculated in the series expansion in powers of g0=gλ 0 up to the terms of third order, assuming some small value for g0 at some large λ0. The result exhibits the same finite sensitivity to small-x regularization as the one obtained in an earlier RGPEP calculation, but the new calculation is simpler than the earlier one because of a simpler generator. This result establishes a degree of universality for pure-gauge QCD in the RGPEP.
The BlueGene/L Supercomputer and Quantum ChromoDynamics
Vranas, P; Soltz, R
2006-10-19
In summary our update contains: (1) Perfect speedup sustaining 19.3% of peak for the Wilson D D-slash Dirac operator. (2) Measurements of the full Conjugate Gradient (CG) inverter that inverts the Dirac operator. The CG inverter contains two global sums over the entire machine. Nevertheless, our measurements retain perfect speedup scaling demonstrating the robustness of our methods. (3) We ran on the largest BG/L system, the LLNL 64 rack BG/L supercomputer, and obtained a sustained speed of 59.1 TFlops. Furthermore, the speedup scaling of the Dirac operator and of the CG inverter are perfect all the way up to the full size of the machine, 131,072 cores (please see Figure II). The local lattice is rather small (4 x 4 x 4 x 16) while the total lattice has been a lattice QCD vision for thermodynamic studies (a total of 128 x 128 x 256 x 32 lattice sites). This speed is about five times larger compared to the speed we quoted in our submission. As we have pointed out in our paper QCD is notoriously sensitive to network and memory latencies, has a relatively high communication to computation ratio which can not be overlapped in BGL in virtual node mode, and as an application is in a class of its own. The above results are thrilling to us and a 30 year long dream for lattice QCD.
Inclusive jet production at the tevatron collider in the Regge limit of quantum chromodynamics
NASA Astrophysics Data System (ADS)
Saleev, V. A.; Shipilova, A. V.; Yatsenko, E. V.
2012-03-01
We consider the inclusive hadroproduction of jets, prompt photons, and b-quark jets in the quasimulti-Regge kinematics approach based on the hypothesis of gluon and quark reggeization in t-channel exchanges at high energies. The data taken by CDF and D0 collaborations at the Fermilab Tevatron collider are well described in the region of x_T = 2p_T /sqrt s lesssim 0.1 without the introduction of any free parameters. In numeric calculations we use the Kimber-Martin-Ryskin prescription for unintegrated gluon and quark distribution functions with Martin-Roberts-Stirling-Thorne collinear parton distribution functions taken as input.
Tests of quantum chromodynamics in exclusive e sup + e sup minus and. gamma. gamma. processes
Brodsky, S.J.
1989-09-01
This paper discusses the following topics: Factorization theorem for exclusive processes; Electromagnetic form factors of baryons; Suppression of final state interactions; The {gamma}{pi}{sub 0} Transition form factor; Exclusive charmonium decays; The {pi}-{rho} puzzle; Time-like compton processes; Multi-hadron production; Heavy Quark exclusive states and form factor zeros in QCD; Exclusive {gamma}{gamma} reactions; Higher twist effects; and Tauonium and threshold {tau}{sup +}{tau}{sup {minus}} production. 41 refs., 15 figs. (LSP)
Hyperon-Nucleon Interactions from Quantum Chromodynamics and the Composition of Dense Nuclear Matter
NASA Astrophysics Data System (ADS)
Beane, S. R.; Chang, E.; Cohen, S. D.; Detmold, W.; Lin, H.-W.; Luu, T. C.; Orginos, K.; Parreño, A.; Savage, M. J.; Walker-Loud, A.
2012-10-01
The low-energy nΣ- interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from a numerical evaluation of the QCD path integral using the technique of lattice QCD. Our calculations, performed at a pion mass of mπ˜389MeV in two large lattice volumes and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The interactions determined from lattice QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties and strengthen model-dependent theoretical arguments that the strange quark is a crucial component of dense nuclear matter.
NASA Technical Reports Server (NTRS)
Applegate, J. H.; Hogan, Craig J.; Scherrer, R. J.
1988-01-01
A simple one-dimensional model is used to describe the evolution of neutron density before and during nucleosynthesis in a high-entropy bubble left over from the cosmic quark-hadron phase transition. It is shown why cosmic nucleosynthesis in such a neutron-rich environment produces a surfeit of elements heavier than lithium. Analytical and numerical techniques are used to estimate the abundances of carbon, nitrogen, and heavier elements up to Ne-22. A high-density neutron-rich region produces enough primordial N-14 to be observed in stellar atmospheres. It shown that very heavy elements may be created in a cosmological r-process; the neutron exposure in the neutron-rich regions is large enough for the Ne-22 to trigger a catastrophic r-process runaway in which the quantity of heavy elements doubles in much less than an expansion time due to fission cycling. A primordial abundance of r-process elements is predicted to appear as an excess of rare earth elements in extremely metal-poor stars.
Hyperon-Nucleon Interactions and the Composition of Dense Matter from Quantum Chromodynamics
Konstantinos Orginos, Silas Beane, Emmanuel Chang, Saul Cohen, Huey-Wen Lin, Tom Luu, Assumpta Parreno, Martin Savage, Andre Walker-Loud, William Detmold
2012-10-01
The low-energy n{Sigma}{sup -} interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase-shifts for this system are determined from a numerical evaluation of the QCD path integral using the technique of Lattice QCD. Our results, performed at a pion mass of m{sub {pi}} ~ 389 MeV in two large lattice volumes, and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The calculated interactions indicate that the strange quark plays an important role in dense matter.
Gubser, Steven S.; Nellore, Abhinav; Pufu, Silviu S.; Rocha, Fabio D.
2008-09-26
We consider classes of translationally invariant black hole solutions whose equations of state closely resemble that of QCD at zero chemical potential. We use these backgrounds to compute the ratio {zeta}/s of bulk viscosity to entropy density. For a class of black holes that exhibits a first-order transition, we observe a sharp rise in {zeta}/s near T{sub c}. For constructions that exhibit a smooth crossover, like QCD does, the rise in {zeta}/s is more modest. We conjecture that divergences in {zeta}/s for black hole horizons are related to extrema of the entropy density as a function of temperature.
NASA Astrophysics Data System (ADS)
Atkinson, D.; Drohm, J. K.; Johnson, P. W.; Stam, K.
1981-11-01
An approximated form of the Dyson-Schwinger equation for the gluon propagator in quarkless QCD is subjected to nonlinear functional and numerical analysis. It is found that solutions exist, and that these have a double pole at the origin of the square of the propagator momentum, together with an accumulation of soft branch points. This analytic structure is strongly suggestive of confinement by infrared slavery.
Three-hair relations for rotating stars: Nonrelativistic limit
Stein, Leo C.; Yagi, Kent; Yunes, Nicolás
2014-06-10
The gravitational field outside of astrophysical black holes is completely described by their mass and spin frequency, as expressed by the no-hair theorems. These theorems assume vacuum spacetimes, and thus they apply only to black holes and not to stars. Despite this, we analytically find that the gravitational potential of arbitrarily rapid, rigidly rotating stars can still be described completely by only their mass, spin angular momentum, and quadrupole moment. Although these results are obtained in the nonrelativistic limit (to leading order in a weak-field expansion of general relativity, GR), they are also consistent with fully relativistic numerical calculations of rotating neutron stars. This description of the gravitational potential outside the source in terms of just three quantities is approximately universal (independent of equation of state). Such universality may be used to break degeneracies in pulsar and future gravitational wave observations to extract more physics and test GR in the strong-field regime.
Continuity properties of the semi-group and its integral kernel in non-relativistic QED
NASA Astrophysics Data System (ADS)
Matte, Oliver
2016-07-01
Employing recent results on stochastic differential equations associated with the standard model of non-relativistic quantum electrodynamics by B. Güneysu, J. S. Møller, and the present author, we study the continuity of the corresponding semi-group between weighted vector-valued Lp-spaces, continuity properties of elements in the range of the semi-group, and the pointwise continuity of an operator-valued semi-group kernel. We further discuss the continuous dependence of the semi-group and its integral kernel on model parameters. All these results are obtained for Kato decomposable electrostatic potentials and the actual assumptions on the model are general enough to cover the Nelson model as well. As a corollary, we obtain some new pointwise exponential decay and continuity results on elements of low-energetic spectral subspaces of atoms or molecules that also take spin into account. In a simpler situation where spin is neglected, we explain how to verify the joint continuity of positive ground state eigenvectors with respect to spatial coordinates and model parameters. There are no smallness assumptions imposed on any model parameter.
Quantum tasks in Minkowski space
NASA Astrophysics Data System (ADS)
Kent, Adrian
2012-11-01
The fundamental properties of quantum information and its applications to computing and cryptography have been greatly illuminated by considering information-theoretic tasks that are provably possible or impossible within non-relativistic quantum mechanics. I describe here a general framework for defining tasks within (special) relativistic quantum theory and illustrate it with examples from relativistic quantum cryptography and relativistic distributed quantum computation. The framework gives a unified description of all tasks previously considered and also defines a large class of new questions about the properties of quantum information in relation to Minkowski causality. It offers a way of exploring interesting new fundamental tasks and applications, and also highlights the scope for a more systematic understanding of the fundamental information-theoretic properties of relativistic quantum theory.
Brodsky, S.J.
1983-11-01
A number of novel features of QCD are reviewed, including the consequences of formation zone and color transparency phenomena in hadronic collisions, the use of automatic scale setting for perturbative predictions, null-zone phenomena as a fundamental test of gauge theory, and the relationship of intrinsic heavy colored particle Fock state components to new particle production. We conclude with a review of the applications of QCD to nuclear multiquark systems. 74 references.
The Thomas–Fermi quark model: Non-relativistic aspects
Liu, Quan Wilcox, Walter
2014-02-15
The first numerical investigation of non-relativistic aspects of the Thomas–Fermi (TF) statistical multi-quark model is given. We begin with a review of the traditional TF model without an explicit spin interaction and find that the spin splittings are too small in this approach. An explicit spin interaction is then introduced which entails the definition of a generalized spin “flavor”. We investigate baryonic states in this approach which can be described with two inequivalent wave functions; such states can however apply to multiple degenerate flavors. We find that the model requires a spatial separation of quark flavors, even if completely degenerate. Although the TF model is designed to investigate the possibility of many-quark states, we find surprisingly that it may be used to fit the low energy spectrum of almost all ground state octet and decuplet baryons. The charge radii of such states are determined and compared with lattice calculations and other models. The low energy fit obtained allows us to extrapolate to the six-quark doubly strange H-dibaryon state, flavor symmetric strange states of higher quark content and possible six quark nucleon–nucleon resonances. The emphasis here is on the systematics revealed in this approach. We view our model as a versatile and convenient tool for quickly assessing the characteristics of new, possibly bound, particle states of higher quark number content. -- Highlights: • First application of the statistical Thomas–Fermi quark model to baryonic systems. • Novel aspects: spin as generalized flavor; spatial separation of quark flavor phases. • The model is statistical, but the low energy baryonic spectrum is successfully fit. • Numerical applications include the H-dibaryon, strange states and nucleon resonances. • The statistical point of view does not encourage the idea of bound many-quark baryons.
ION ACCELERATION IN NON-RELATIVISTIC ASTROPHYSICAL SHOCKS
Gargate, L.; Spitkovsky, A.
2012-01-01
We explore the physics of shock evolution and particle acceleration in non-relativistic collisionless shocks using hybrid simulations. We analyze a wide range of physical parameters relevant to the acceleration of cosmic rays (CRs) in astrophysical shock scenarios. We show that there are fundamental differences between high and low Mach number shocks in terms of the electromagnetic turbulence generated in the pre-shock zone; dominant modes are resonant with the streaming CRs in the low Mach number regime, while both resonant and non-resonant modes are present for high Mach numbers. Energetic power-law tails for ions in the downstream plasma account for up to 15% of the incoming upstream flow energy, distributed over {approx}5% of the particles in a power law with slope -2 {+-} 0.2 in energy. Quasi-parallel shocks with {theta} {<=} 45 Degree-Sign are good ion accelerators, while power laws are greatly suppressed for quasi-perpendicular shocks, {theta} > 45 Degree-Sign . The efficiency of conversion of flow energy into the energy of accelerated particles peaks at {theta} = 15 Degree-Sign -30 Degree-Sign and M{sub A} = 6, and decreases for higher Mach numbers, down to {approx}2% for M{sub A} = 31. Accelerated particles are produced by diffusive shock acceleration (DSA) and by shock drift acceleration (SDA) mechanisms, with the SDA contribution to the overall energy gain increasing with magnetic inclination. We also present a direct comparison between hybrid and fully kinetic particle-in-cell results at early times. In supernova remnant (SNR) shocks, particle acceleration will be significant for low Mach number quasi-parallel flows (M{sub A} < 30, {theta} < 45). This finding underscores the need for an effective magnetic amplification mechanism in SNR shocks.
Remote State Preparation for Quantum Fields
NASA Astrophysics Data System (ADS)
Ber, Ran; Zohar, Erez
2016-07-01
Remote state preparation is generation of a desired state by a remote observer. In spite of causality, it is well known, according to the Reeh-Schlieder theorem, that it is possible for relativistic quantum field theories, and a "physical" process achieving this task, involving superoscillatory functions, has recently been introduced. In this work we deal with non-relativistic fields, and show that remote state preparation is also possible for them, hence obtaining a Reeh-Schlieder-like result for general fields. Interestingly, in the nonrelativistic case, the process may rely on completely different resources than the ones used in the relativistic case.
Dirac oscillator and nonrelativistic Snyder-de Sitter algebra
Stetsko, M. M. E-mail: mykola@ktf.franko.lviv.ua
2015-01-15
Three dimensional Dirac oscillator was considered in space with deformed commutation relations known as Snyder-de Sitter algebra. Snyder-de Sitter commutation relations give rise to appearance of minimal uncertainties in position as well as in momentum. To derive energy spectrum and wavefunctions of the Dirac oscillator, supersymmetric quantum mechanics and shape invariance technique were applied.
Dirac oscillator and nonrelativistic Snyder-de Sitter algebra
NASA Astrophysics Data System (ADS)
Stetsko, M. M.
2015-01-01
Three dimensional Dirac oscillator was considered in space with deformed commutation relations known as Snyder-de Sitter algebra. Snyder-de Sitter commutation relations give rise to appearance of minimal uncertainties in position as well as in momentum. To derive energy spectrum and wavefunctions of the Dirac oscillator, supersymmetric quantum mechanics and shape invariance technique were applied.
A Non-Relativistic Look at the Compton Effect
ERIC Educational Resources Information Center
Feller, Steve; Giri, Sandeep; Zakrasek, Nicholas; Affatigato, Mario
2014-01-01
In a usual modern physics class the Compton effect is used as the pedagogical model for introducing relativity into quantum effects. The shift in photon wavelengths is usually introduced and derived using special relativity. Indeed, this works well for explaining the effect. However, in the senior author's class one of the student coauthors…
Comment on ``Arrival time in quantum mechanics'' and ``Time of arrival in quantum mechanics''
NASA Astrophysics Data System (ADS)
Kijowski, Jerzy
1999-01-01
Contrary to claims contained in papers by Grot, Rovelli, and Tate [Phys. Rev. A 54, 4676 1996)] and Delgado and Muga [Phys. Rev. A 56, 3425 (1997)], the ``time operator,'' which I have constructed [Rep. Math. Phys. 6, 361 (1974)] in an axiomatic way, is a self-adjoint operator existing in a usual Hilbert space of (nonrelativistic or relativistic) quantum mechanics.
Relativistic and non-relativistic solitons in plasmas
NASA Astrophysics Data System (ADS)
Barman, Satyendra Nath
This thesis entitled as "Relativistic and Non-relativistic Solitons in Plasmas" is the embodiment of a number of investigations related to the formation of ion-acoustic solitary waves in plasmas under various physical situations. The whole work of the thesis is devoted to the studies of solitary waves in cold and warm collisionless magnetized or unmagnetized plasmas with or without relativistic effect. To analyze the formation of solitary waves in all our models of plasmas, we have employed two established methods namely - reductive perturbation method to deduce the Korteweg-de Vries (KdV) equation, the solutions of which represent the important but near exact characteristic concepts of soliton-physics. Next, the pseudopotential method to deduce the energy integral with total nonlinearity in the coupling process for exact characteristic results of solitons has been incorporated. In Chapter 1, a brief description of plasma in nature and laboratory and its generation are outlined elegantly. The nonlinear differential equations to characterize solitary waves and the relevant but important methods of solutions have been mentioned in this chapter. The formation of solitary waves in unmagnetized and magnetized plasmas, and in relativistic plasmas has been described through mathematical entity. Applications of plasmas in different fields are also put forwarded briefly showing its importance. The study of plasmas as they naturally occur in the universe encompasses number of topics including sun's corona, solar wind, planetary magnetospheres, ionospheres, auroras, cosmic rays and radiation. The study of space weather to understand the universe, communications and the activities of weather satellites are some useful areas of space plasma physics. The surface cleaning, sterilization of food and medical appliances, killing of bacteria on various surfaces, destroying of viruses, fungi, spores and plasma coating in industrial instruments ( like computers) are some of the fields
ELECTRON INJECTION BY WHISTLER WAVES IN NON-RELATIVISTIC SHOCKS
Riquelme, Mario A.; Spitkovsky, Anatoly E-mail: anatoly@astro.princeton.edu
2011-05-20
Electron acceleration to non-thermal, ultra-relativistic energies ({approx}10-100 TeV) is revealed by radio and X-ray observations of shocks in young supernova remnants (SNRs). The diffusive shock acceleration (DSA) mechanism is usually invoked to explain this acceleration, but the way in which electrons are initially energized or 'injected' into this acceleration process starting from thermal energies is an unresolved problem. In this paper we study the initial acceleration of electrons in non-relativistic shocks from first principles, using two- and three-dimensional particle-in-cell (PIC) plasma simulations. We systematically explore the space of shock parameters (the Alfvenic Mach number, M{sub A} , the shock velocity, v{sub sh}, the angle between the upstream magnetic field and the shock normal, {theta}{sub Bn}, and the ion to electron mass ratio, m{sub i} /m{sub e} ). We find that significant non-thermal acceleration occurs due to the growth of oblique whistler waves in the foot of quasi-perpendicular shocks. This acceleration strongly depends on using fairly large numerical mass ratios, m{sub i} /m{sub e} , which may explain why it had not been observed in previous PIC simulations of this problem. The obtained electron energy distributions show power-law tails with spectral indices up to {alpha} {approx} 3-4. The maximum energies of the accelerated particles are consistent with the electron Larmor radii being comparable to that of the ions, indicating potential injection into the subsequent DSA process. This injection mechanism, however, requires the shock waves to have fairly low Alfenic Mach numbers, M{sub A} {approx}< 20, which is consistent with the theoretical conditions for the growth of whistler waves in the shock foot (M{sub A} {approx}< (m{sub i} /m{sub e}){sup 1/2}). Thus, if the whistler mechanism is the only robust electron injection process at work in SNR shocks, then SNRs that display non-thermal emission must have significantly amplified
Eavesdropping of quantum communication from a noninertial frame
Bradler, K.
2007-02-15
We introduce a relativistic version of the quantum encryption protocol by considering two inertial observers who wish to securely transmit quantum information encoded in a free scalar quantum field state forming Minkowski particles. In a nonrelativistic setting a certain amount of shared classical resources is necessary to perfectly encrypt the state. We show that in the case of a uniformly accelerated eavesdropper the communicating parties need to share (asymptotically in the limit of infinite acceleration) just half of the classical resources.
The quantum mechanics of cosmology.
NASA Astrophysics Data System (ADS)
Hartle, James B.
to the Quantum Mechanics of a Non-Relativistic Particle * Semiclassical Prediction in Quantum Cosmology * ACKNOWLEDGEMENTS * REFERENCES * APPENDIX: BUZZWORDS
Sadiq, Safeer; Mahmood, S.; Haque, Q.; Ali, Munazza Zulfiqar
2014-09-20
The propagation of electrostatic waves in a dense magnetized electron-positron-ion (EPI) plasma with nonrelativistic and ultrarelativistic degenerate electrons and positrons is investigated. The linear dispersion relation is obtained for slow and fast electrostatic waves in the EPI plasma. The limiting cases for ion acoustic wave (slow) and ion cyclotron wave (fast) are also discussed. Using the reductive perturbation method, two-dimensional propagation of ion acoustic solitons is found for both the nonrelativistic and ultrarelativistic degenerate electrons and positrons. The effects of positron concentration, magnetic field, and mass of ions on ion acoustic solitons are shown in numerical plots. The proper form of Fermi temperature for nonrelativistic and ultrarelativistic degenerate electrons and positrons is employed, which has not been used in earlier published work. The present investigation is useful for the understanding of linear and nonlinear electrostatic wave propagation in the dense magnetized EPI plasma of compact stars. For illustration purposes, we have applied our results to a pulsar magnetosphere.
Correspondence of I- and Q-balls as non-relativistic condensates
Mukaida, Kyohei; Takimoto, Masahiro E-mail: takimoto@hep-th.phys.s.u-tokyo.ac.jp
2014-08-01
If a real scalar field is dominated by non-relativistic modes, then it approximately conserves its particle number and obeys an equation that governs a complex scalar field theory with a conserved global U(1) symmetry. From this fact, it is shown that the I-ball (oscillon) can be naturally understood as a projection (e.g., real part) of the non-relativistic Q-ball solution. In particular, we clarify that the stability of the I-ball is guaranteed by the U(1) symmetry in the corresponding complex scalar field theory as long as the non-relativistic condition holds. We also discuss the longevity of I-ball from the perspective of the complex scalar field in terms of U(1) charge violating processes.
NASA Astrophysics Data System (ADS)
Białynicki-Birula, I.; Cirone, M. A.; Dahl, J. P.; Seligman, T. H.; Straub, F.; Schleich, W. P.
2003-09-01
We present Heisenberg's equation of motion for the radial variable of a free non-relativistic particle in D dimensions. The resulting radial force consists of three contributions: (i) the quantum fictitious force which is either attractive or repulsive depending on the number of dimensions, (ii) a singular quantum force located at the origin, and (iii) the centrifugal force associated with non-vanishing angular momentum. Moreover, we use Heisenberg's uncertainty relation to introduce a lower bound for the kinetic energy of an ensemble of neutral particles. This bound is quadratic in the number of atoms and can be traced back to the repulsive quantum fictitious potential. All three forces arise for a free particle: “Force without force”.
Magnetically driven quantum heat engine.
Muñoz, Enrique; Peña, Francisco J
2014-05-01
We studied the efficiency of two different schemes for a magnetically driven quantum heat engine, by considering as the "working substance" a single nonrelativistic particle trapped in a cylindrical potential well, in the presence of an external magnetic field. The first scheme is a cycle, composed of two adiabatic and two isoenergetic reversible trajectories in configuration space. The trajectories are driven by a quasistatic modulation of the external magnetic-field intensity. The second scheme is a variant of the former, where the isoenergetic trajectories are replaced by isothermal ones, along which the system is in contact with macroscopic thermostats. This second scheme constitutes a quantum analog of the classical Carnot cycle.
Nontrivial systems and the necessity of the scalar quantum mechanics axioms
Kotulek, Jan
2009-06-15
We discuss the necessity of the axioms of scalar quantum mechanics introduced by Paschke and clearly demonstrate their geometric and/or physical meaning. We show that reasonable nonrelativistic quantum mechanics is exactly specified by the axioms. A system describing the electric Aharonov-Bohm effect is presented. It illustrates the topological obstructions for the existence of a Hamiltonian.
Spin-Zero Particles must be Bosons: A New Proof within Nonrelativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Peshkin, Murray
2006-01-01
The key assumption is that of Leinaas and Myrheim and of Berry and Robbins, here specialized to spin zero: for n particles, the argument of the wave function should be the unordered multiplet { r 1, r 2,..., r n }. I also make use of the requirement that wave functions in the domain of the Hamiltonian must be continuous functions of the spatial variables. The new proof presented here has advantages of simplicity and transparency in comparison with earlier work based on the same two principles and it uses weaker assumptions, especially avoiding the use of rotations of the relative coordinate of identical particles.
NASA Astrophysics Data System (ADS)
Cannoni, Mirco
2016-03-01
We find an exact formula for the thermally averaged cross section times the relative velocity < σ v_{text {rel}} rangle with relativistic Maxwell-Boltzmann statistics. The formula is valid in the effective field theory approach when the masses of the annihilation products can be neglected compared with the dark matter mass and cut-off scale. The expansion at x=m/T≫ 1 directly gives the nonrelativistic limit of < σ v_{text {rel}}rangle , which is usually used to compute the relic abundance for heavy particles that decouple when they are nonrelativistic. We compare this expansion with the one obtained by expanding the total cross section σ (s) in powers of the nonrelativistic relative velocity v_r. We show the correct invariant procedure that gives the nonrelativistic average < σ _{nr} v_r rangle _{nr} coinciding with the large x expansion of < σ v_{text {rel}}rangle in the comoving frame. We explicitly formulate flux, cross section, thermal average, collision integral of the Boltzmann equation in an invariant way using the true relativistic relative v_text {rel}, showing the uselessness of the Møller velocity and further elucidating the conceptual and numerical inconsistencies related with its use.
World Sheet Commuting beta-gamma CFT and Non-Relativistic StringTheories
Kim, Bom Soo
2007-08-30
We construct a sigma model in two dimensions with Galilean symmetry in flat target space similar to the sigma model of the critical string theory with Lorentz symmetry in 10 flat spacetime dimensions. This is motivated by the works of Gomis and Ooguri[1] and Danielsson et. al.[2, 3]. Our theory is much simpler than their theory and does not assume a compact coordinate. This non-relativistic string theory has a bosonic matter {beta}{gamma} CFT with the conformal weight of {beta} as 1. It is natural to identify time as a linear combination of {gamma} and {bar {gamma}} through an explicit realization of the Galilean boost symmetry. The angle between {gamma} and {bar {gamma}} parametrizes one parameter family of selection sectors. These selection sectors are responsible for having a non-relativistic dispersion relation without a nontrivial topology in the non-relativistic setup, which is one of the major differences from the previous works[1, 2, 3]. This simple theory is the non-relativistic analogue of the critical string theory, and there are many different avenues ahead to be investigated. We mention a possible consistent generalization of this theory with different conformal weights for the {beta}{gamma} CFT. We also mention supersymmetric generalizations of these theories.
NASA Astrophysics Data System (ADS)
Griffiths, Robert B.
2001-11-01
Quantum mechanics is one of the most fundamental yet difficult subjects in physics. Nonrelativistic quantum theory is presented here in a clear and systematic fashion, integrating Born's probabilistic interpretation with Schrödinger dynamics. Basic quantum principles are illustrated with simple examples requiring no mathematics beyond linear algebra and elementary probability theory. The quantum measurement process is consistently analyzed using fundamental quantum principles without referring to measurement. These same principles are used to resolve several of the paradoxes that have long perplexed physicists, including the double slit and Schrödinger's cat. The consistent histories formalism used here was first introduced by the author, and extended by M. Gell-Mann, J. Hartle and R. Omnès. Essential for researchers yet accessible to advanced undergraduate students in physics, chemistry, mathematics, and computer science, this book is supplementary to standard textbooks. It will also be of interest to physicists and philosophers working on the foundations of quantum mechanics. Comprehensive account Written by one of the main figures in the field Paperback edition of successful work on philosophy of quantum mechanics
Testing Quantum Gravity Induced Nonlocality via Optomechanical Quantum Oscillators.
Belenchia, Alessio; Benincasa, Dionigi M T; Liberati, Stefano; Marin, Francesco; Marino, Francesco; Ortolan, Antonello
2016-04-22
Several quantum gravity scenarios lead to physics below the Planck scale characterized by nonlocal, Lorentz invariant equations of motion. We show that such nonlocal effective field theories lead to a modified Schrödinger evolution in the nonrelativistic limit. In particular, the nonlocal evolution of optomechanical quantum oscillators is characterized by a spontaneous periodic squeezing that cannot be generated by environmental effects. We discuss constraints on the nonlocality obtained by past experiments, and show how future experiments (already under construction) will either see such effects or otherwise cast severe bounds on the nonlocality scale (well beyond the current limits set by the Large Hadron Collider). This paves the way for table top, high precision experiments on massive quantum objects as a promising new avenue for testing some quantum gravity phenomenology. PMID:27152787
Testing Quantum Gravity Induced Nonlocality via Optomechanical Quantum Oscillators
NASA Astrophysics Data System (ADS)
Belenchia, Alessio; Benincasa, Dionigi M. T.; Liberati, Stefano; Marin, Francesco; Marino, Francesco; Ortolan, Antonello
2016-04-01
Several quantum gravity scenarios lead to physics below the Planck scale characterized by nonlocal, Lorentz invariant equations of motion. We show that such nonlocal effective field theories lead to a modified Schrödinger evolution in the nonrelativistic limit. In particular, the nonlocal evolution of optomechanical quantum oscillators is characterized by a spontaneous periodic squeezing that cannot be generated by environmental effects. We discuss constraints on the nonlocality obtained by past experiments, and show how future experiments (already under construction) will either see such effects or otherwise cast severe bounds on the nonlocality scale (well beyond the current limits set by the Large Hadron Collider). This paves the way for table top, high precision experiments on massive quantum objects as a promising new avenue for testing some quantum gravity phenomenology.
Testing Quantum Gravity Induced Nonlocality via Optomechanical Quantum Oscillators.
Belenchia, Alessio; Benincasa, Dionigi M T; Liberati, Stefano; Marin, Francesco; Marino, Francesco; Ortolan, Antonello
2016-04-22
Several quantum gravity scenarios lead to physics below the Planck scale characterized by nonlocal, Lorentz invariant equations of motion. We show that such nonlocal effective field theories lead to a modified Schrödinger evolution in the nonrelativistic limit. In particular, the nonlocal evolution of optomechanical quantum oscillators is characterized by a spontaneous periodic squeezing that cannot be generated by environmental effects. We discuss constraints on the nonlocality obtained by past experiments, and show how future experiments (already under construction) will either see such effects or otherwise cast severe bounds on the nonlocality scale (well beyond the current limits set by the Large Hadron Collider). This paves the way for table top, high precision experiments on massive quantum objects as a promising new avenue for testing some quantum gravity phenomenology.
Chirality Quantum Phase Transition in Noncommutative Dirac Oscillator
NASA Astrophysics Data System (ADS)
Wang, Shao-Hua; Hou, Yu-Long; Wang, Qing; Long, Zheng-Wen; Jing, Jian
2014-12-01
The charged Dirac oscillator on a noncommutative plane coupling to a uniform perpendicular magnetic held is studied in this paper. We map the noncommutative plane to a commutative one by means of Bopp shift and study this problem on the commutative plane. We find that this model can be mapped onto a quantum optics model which contains Anti—Jaynes—Cummings (AJC) or Jaynes—Cummings (JC) interactions when a dimensionless parameter ζ (which is the function of the intensity of the magnetic held) takes values in different regimes. Furthermore, this model behaves as experiencing a chirality quantum phase transition when the dimensionless parameter ζ approaches the critical point. Several evidences of the chirality quantum phase transition are presented. We also study the non-relativistic limit of this model and find that a similar chirality quantum phase transition takes place in its non-relativistic limit.
Spin-Interactions and the Non-relativistic Limit of Electrodynamics
NASA Astrophysics Data System (ADS)
Saue, Trond
This chapter discusses how to extinguish spin-orbit interactions and/or scalar relativistic effects from four-component relativistic molecular calculations in order to assess their importance on molecular properties. It is pointed out that standard non-relativistic calculations use the non-relativistic free-particle Hamiltonian , but the relativistic Hamiltonian which describes the interaction between particles and fields. In the strict non-relativistic limit, electrodynamics reduce to electrostatics, that is there are no effects of retardation and no magnetic interactions. It is, however, perfectly reasonable from a pragmatic point of view to introduce both scalar and vector potentials in a non-relativistic framework. Non-relativistic theory can perfectly well accommodate magnetic sources, including spin, but does not provide a mechanism for generating them. We demonstrate that the pragmatic approach leads to some inconsistencies in that non-relativistic theory cannot describe spin-same orbit interactions, but spin-other orbit interactions. We also emphasize that the distinction between spin-orbit interactions and other spin interactions is somewhat artificial and highly dependent on the chosen reference frame. In a previous paper [L. Visscher and T. Saue, J. Chem. Phys., 2000, 113, 3996] we demonstrated how to eliminate spin-orbit interaction from four-component relativistic calculations of spectroscopic constants by deleting the quaternion imaginary parts of matrix representations of the modified Dirac equation. In this chapter, we discuss the extension of this approach to second-order electric and magnetic properties. We will demonstrate the elimination of poles corresponding to spin-forbidden transitions from the dispersion of the dipole polarizability of the mercury atom. More care is needed when considering second-order magnetic properties in that the elimination of quaternion imaginary parts will extinguish all spin interactions. A procedure is developed
Energy transmission using recyclable quantum entanglement.
Ye, Ming-Yong; Lin, Xiu-Min
2016-01-01
It is known that faster-than-light (FTL) transmission of energy could be achieved if the transmission were considered in the framework of non-relativistic classical mechanics. Here we show that FTL transmission of energy could also be achieved if the transmission were considered in the framework of non-relativistic quantum mechanics. In our transmission protocol a two-spin Heisenberg model is considered and the energy is transmitted by two successive local unitary operations on the initially entangled spins. Our protocol does not mean that FTL transmission can be achieved in reality when the theory of relativity is considered, but it shows that quantum entanglement can be used in a recyclable way in energy transmission. PMID:27465431
Energy transmission using recyclable quantum entanglement
NASA Astrophysics Data System (ADS)
Ye, Ming-Yong; Lin, Xiu-Min
2016-07-01
It is known that faster-than-light (FTL) transmission of energy could be achieved if the transmission were considered in the framework of non-relativistic classical mechanics. Here we show that FTL transmission of energy could also be achieved if the transmission were considered in the framework of non-relativistic quantum mechanics. In our transmission protocol a two-spin Heisenberg model is considered and the energy is transmitted by two successive local unitary operations on the initially entangled spins. Our protocol does not mean that FTL transmission can be achieved in reality when the theory of relativity is considered, but it shows that quantum entanglement can be used in a recyclable way in energy transmission.
Gravity Dual for Reggeon Field Theory and Nonlinear Quantum Finance
NASA Astrophysics Data System (ADS)
Nakayama, Yu
We study scale invariant but not necessarily conformal invariant deformations of nonrelativistic conformal field theories from the dual gravity viewpoint. We present the corresponding metric that solves the Einstein equation coupled with a massive vector field. We find that, within the class of metric we study, when we assume the Galilean invariance, the scale invariant deformation always preserves the nonrelativistic conformal invariance. We discuss applications to scaling regime of Reggeon field theory and nonlinear quantum finance. These theories possess scale invariance but may or may not break the conformal invariance, depending on the underlying symmetry assumptions.
Intermediate quantum statistics for identical objects
Kuryshkin, V.V.
1988-11-01
Methods to construct various algebras of creation and annihilation operators of physical objects in complex quantum state spaces with a nonnegative metric are proposed. All allowed algebras for the cases of identical nonrelativistic systems in the second quantization of the Schrodinger equation, of identical quanta of relativistic tensor fields, and of identical quanta of relativistic spinor fields are constructed. A comparison of the obtained algebras with the well-known algebras of this type (Fermi, Bose, para-Fermi, and superalgebras) is given.
Acceleration of non-relativistic electrons at a dielectric grating structure: Status report
Breuer, John; Hommelhoff, Peter
2012-12-21
We report on an experiment aiming at a proof-of-concept of a non-relativistic direct laser accelerator. The system is based on a fused-silica transmission grating illuminated by Titanium:sapphire femtosecond pulses in order to excite evanescent spatial modes, which propagate synchronously with 28 keV electrons originating from an electron column of a scanning electron microscope. The grating period is 750 nm, and we use the third spatial harmonic to continuously accelerate the non-relativistic electrons. With a laser pulse energy of about 150 nJ numerical simulations show expected accelerating gradients of up to 60 MeV/m and an energy gain of around 300 eV at a distance of 100 nm away from the grating surface. The current status of the experiment is reported.
Cavity loss factors of non-relativistic beams for Project X
Lunin, A.; Yakovlev, V.; Kazakov, S.; /Fermilab
2011-03-01
Cavity loss factor calculation is an important part of the total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the addition of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.
Screening Effects on Nonrelativistic Bremsstrahlung in the Scattering of Electrons by Neutral Atoms
NASA Technical Reports Server (NTRS)
Jung, Young-Dae; Lee, Kun-Sang
1995-01-01
Atomic screening effects on nonrelativistic electron-atom bremsstrahlung radiation are investigated using a simple analytic solution of the Thomas-Fermi model for many-electron atoms. The Born approximation is assumed for the initial and final states of the projectile electron. The results show that the screening effect is important in the soft radiation region and is decreasing with increasing radiation. These results help provide correct information about the behavior of bound electrons in the target atom in bremsstrahlung processes.
Hussain, S.; Mahmood, S.; Rehman, Aman-ur-
2014-11-15
Linear and nonlinear propagation of magnetosonic waves in the perpendicular direction to the ambient magnetic field is studied in dense plasmas for non-relativistic and ultra-relativistic degenerate electrons pressure. The sources of nonlinearities are the divergence of the ions and electrons fluxes, Lorentz forces on ions and electrons fluids and the plasma current density in the system. The Korteweg-de Vries equation for magnetosonic waves propagating in the perpendicular direction of the magnetic field is derived by employing reductive perturbation method for non-relativistic as well as ultra-relativistic degenerate electrons pressure cases in dense plasmas. The plots of the magnetosonic wave solitons are also shown using numerical values of the plasma parameters such a plasma density and magnetic field intensity of the white dwarfs from literature. The dependence of plasma density and magnetic field intensity on the magnetosonic wave propagation is also pointed out in dense plasmas for both non-relativistic and ultra-relativistic degenerate electrons pressure cases.
Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar
2015-09-15
A numerical study is presented of the nonlinear dynamics of a magnetized, cold, non-relativistic plasma, in the presence of electron-ion collisions. The ions are considered to be immobile while the electrons move with non-relativistic velocities. The primary interest is to study the effects of the collision parameter, external magnetic field strength, and the initial electromagnetic polarization on the evolution of the plasma system.
Nelson, C.A.
1993-12-01
The author has constructed a number of fundamental tests which can be used to probe discrete symmetries, and their possible violations, in the required {open_quotes}new physics{close_quotes} beyond the standard model. On-going experiments with unpolarized e{sup {minus}} e{sup +} collisions contain many events for the production-decay sequence e{sup {minus}}e{sup +} {yields} Z{sup o}, {gamma}{sup *} {yields} {tau}{sup {minus}}{tau}{sup +} {yields} (A{sup {minus}}X)(B{sup +}X). By inclusion of {rho} polarimetry observables such experiments enable two distinct tests for leptonic CP violation in {tau} {yields} {rho}{nu} decay (similarly in {tau} {yields} a{sub 1}{nu} decay) by generalization of the energy correlation function for Z{sup o}, or {gamma}{sup *} {yields} {tau}{sup {minus}}{tau}{sup +} {yields}({rho}{sup {minus}}{nu})({rho}{sup +}{bar {nu}}). In other research programs, the author is (i) continuing to investigate the proposal that partons be identified with nearly degenerate, coherent quark-gluon {open_quotes}jet{close_quotes} states, and is (ii) investigating the novel consequences of the possible existence of q-bosons and of a related completeness relation for the q-analogue coherent states. This year the author has also written papers on the zeros of the q-analogue exponential function, and on the number and phase uncertainties of the q-analogue quantized field.
Mueller, B.; Springer, R.P.
1995-05-15
A brief summary of the progress made for the year is given for each of the following areas: (1) quark-gluon plasma and relativistic heavy ion collisions (nine contributions); (2) effective theories for hadrons and nuclei (four contributions); (4) renormalization group approach to field theory at finite temperature; (5) symmetry-preserving regularization; and (6) an effective field theory approach to the cosmological constant problem.
NASA Astrophysics Data System (ADS)
Moreland, J. Scott; Soltz, Ron A.
2016-04-01
Hydrodynamic calculations of ultrarelativistic heavy-ion collisions are performed using the iebe-vishnu 2+1-dimensional code with fluctuating initial conditions and three different parametrizations of the lattice QCD equations of state: continuum extrapolations for stout and HISQ/tree actions, as well as the s95p-v1 parametrization based upon calculations using the p4 action. All parametrizations are matched to a hadron resonance gas equation of state at T =155 MeV, at which point the calculations are continued using the urqmd hadronic cascade. Simulations of √{sN N}=200 GeV Au+Au collisions in three centrality classes are used to quantify anisotropic flow developed in the hydrodynamic phase of the collision as well as particle spectra and pion Hanbury-Brown-Twiss (HBT) radii after hadronic rescattering, which are compared with experimental data. Experimental observables for the stout and HISQ/tree equations of state are observed to differ by less than a few percent for all observables, while the s95p-v1 equation of state generates spectra and flow coefficients which differ by ˜10 -20 % . Calculations in which the HISQ/tree equation of state is sampled from the published error distribution are also observed to differ by less than a few percent.
Classical analog of quantum phase
Ord, G.N.
1992-07-01
A modified version of the Feynman relativistic chessboard model (FCM) is investigated in which the paths involved are spirals in the space-time. Portions of the paths in which the particle`s proper time is reversed are interpreted in terms of antiparticles. With this intepretation the particle-antiparticle field produced by such trajectories provides a classical analog of the phase associated with particle paths in the unmodified FCM. It is shwon that in the nonrelativistic limit the resulting kernel is the correct Dirac propagator and that particle-antiparticle symmetry is in this case responsible for quantum interference. 7 refs., 3 figs.
On the geometrization of quantum mechanics
NASA Astrophysics Data System (ADS)
Tavernelli, Ivano
2016-08-01
Nonrelativistic quantum mechanics is commonly formulated in terms of wavefunctions (probability amplitudes) obeying the static and the time-dependent Schrödinger equations (SE). Despite the success of this representation of the quantum world a wave-particle duality concept is required to reconcile the theory with observations (experimental measurements). A first solution to this dichotomy was introduced in the de Broglie-Bohm theory according to which a pilot-wave (solution of the SE) is guiding the evolution of particle trajectories. Here, I propose a geometrization of quantum mechanics that describes the time evolution of particles as geodesic lines in a curved space, whose curvature is induced by the quantum potential. This formulation allows therefore the incorporation of all quantum effects into the geometry of space-time, as it is the case for gravitation in the general relativity.
J/Ψ production in two-photon collisions at next-to-leading order
NASA Astrophysics Data System (ADS)
Mihaila, L.
2004-10-01
In this paper, we report on the calculation of the cross section of J/Ψ plus jet inclusive production in direct γγ collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD). Theoretical predictions for the future e+e- linear collider TESLA are also presented.
Spacetime variation of Lorentz-violation coefficients at a nonrelativistic scale
NASA Astrophysics Data System (ADS)
Lane, Charles D.
2016-07-01
The notion of uniform and/or constant tensor fields of rank >0 is incompatible with general curved spacetimes. This work considers the consequences of certain tensor-valued coefficients for Lorentz violation in the Standard-Model extension varying with spacetime position. We focus on two of the coefficients, aμ and bμ , that characterize Lorentz violation in massive fermions, particularly in those fermions that constitute ordinary matter. We calculate the nonrelativistic Hamiltonian describing these effects, and use it to extract the sensitivity of several precision experiments to coefficient variation.
Generation of high-power tunable terahertz-radiation by nonrelativistic beam-echo harmonic effect
NASA Astrophysics Data System (ADS)
Gong, Huarong; Travish, Gil; Xu, Jin; Wei, Yanyu; Feng, Jinjun; Gong, Yubin
2013-01-01
A new type of terahertz radiation source based on the nonrelativistic electron beam-wave interaction is proposed. Here, the beam echo harmonic effect is applied to a traveling wave tube like device. The scheme is configured as a combination of a frequency multiplier and amplifier with, for instance, W-band (millimeter wave) input signals and terahertz output power. A one-dimensional model of this device shows that a 10th order harmonic-wave can be generated while other harmonic waves are suppressed. The device only requires a readily available input source (W-band), and the output frequency can be tuned continuously over a wide band.
NASA Astrophysics Data System (ADS)
Lin, Chris L.; Ordóñez, Carlos R.
2016-10-01
We regulate in Euclidean space the Jacobian under scale transformations for two-dimensional nonrelativistic fermions and bosons interacting via contact interactions and compare the resulting scaling anomalies. For fermions, Grassmannian integration inverts the Jacobian; however, this effect is canceled by the regularization procedure and a result similar to that of bosons is attained. We show the independence of the result with respect to the regulating function, and show the robustness of our methods by comparing the procedure with an effective potential method using both cutoff and ζ -function regularization.
Nicolis, Alberto; Piazza, Federico
2013-01-01
We adapt the Goldstone theorem to study spontaneous symmetry breaking in relativistic theories at finite charge density. It is customary to treat systems at finite density via nonrelativistic Hamiltonians. Here, we highlight the importance of the underlying relativistic dynamics. This leads to seemingly new results whenever the charge in question is spontaneously broken and does not commute with other broken charges. We find that that the latter interpolate gapped excitations. In contrast, all existing versions of the Goldstone theorem predict the existence of gapless modes. We derive exact nonperturbative expressions for their gaps, in terms of the chemical potential and of the symmetry algebra.
NASA Astrophysics Data System (ADS)
Pennisi, S.; Carrisi, M. C.; Scanu, A.
2006-03-01
It is well known that, in the relativistic context the relativity principle isn't imposed by separating variables into convective and non convective parts, but by imposing that the costitutive functions satisfy particular conditions; likely to this, the present considerations show that the same results are obtained also in the classical context. The result is achieved by taking the non-relativistic limit of Einstein's Relativity Principle. This fact furnishes further arguments on the naturalness of the work “A new method to exploit the Entropy Principle and Galilean invariance in the macroscopic approach of Extended Thermodynamics” by Pennisi and Ruggeri.
η(c) production at the LHC challenges nonrelativistic QCD factorization.
Butenschoen, Mathias; He, Zhi-Guo; Kniehl, Bernd A
2015-03-01
We analyze the first measurement of η_{c} production, performed by the LHCb Collaboration, in the nonrelativistic QCD (NRQCD) factorization framework at next-to-leading order (NLO) in the strong-coupling constant α_{s} and the relative velocity v of the bound quarks including the feeddown from h_{c} mesons. Converting the long-distance matrix elements extracted by various groups from J/ψ yield and polarization data to the η_{c} case using heavy-quark spin symmetry, we find that the resulting NLO NRQCD predictions greatly overshoot the LHCb data, while the color-singlet model provides an excellent description.
Propagation of a nonrelativistic electron beam in a plasma in a magnetic field
Okuda, H.; Horton, R.; Ono, M.; Ashour-Abdalla, M.
1986-10-01
Propagation of a nonrelativistic electron beam in a plasma in a strong magnetic field has been studied using electrostatic one-dimensional particle simulation models. Electron beams of finite pulse length and of continuous injection are followed in time to study the effects of beam-plasma interaction on the beam propagation. For the case of pulsed beam propagation, it is found that the beam distribution rapidly spreads in velocity space generating a plateaulike distribution with a high energy tail extending beyond the initial beam velocity.
Accioly, Antonio; Dias, Marco
2004-11-15
The problem of computing the effective nonrelativistic potential U{sub D} for the interaction of charged-scalar bosons, within the context of D-dimensional electromagnetism with a cutoff, is reduced to quadratures. It is shown that U{sub 3} cannot bind a pair of identical charged-scalar bosons; nevertheless, numerical calculations indicate that boson-boson bound states do exist in the framework of three-dimensional higher-derivative electromagnetism augmented by a topological Chern-Simons term.
η(c) production at the LHC challenges nonrelativistic QCD factorization.
Butenschoen, Mathias; He, Zhi-Guo; Kniehl, Bernd A
2015-03-01
We analyze the first measurement of η_{c} production, performed by the LHCb Collaboration, in the nonrelativistic QCD (NRQCD) factorization framework at next-to-leading order (NLO) in the strong-coupling constant α_{s} and the relative velocity v of the bound quarks including the feeddown from h_{c} mesons. Converting the long-distance matrix elements extracted by various groups from J/ψ yield and polarization data to the η_{c} case using heavy-quark spin symmetry, we find that the resulting NLO NRQCD predictions greatly overshoot the LHCb data, while the color-singlet model provides an excellent description. PMID:25793805
Generation of high-power tunable terahertz-radiation by nonrelativistic beam-echo harmonic effect
Gong Huarong; Xu Jin; Wei Yanyu; Gong Yubin; Travish, Gil; Feng Jinjun
2013-01-15
A new type of terahertz radiation source based on the nonrelativistic electron beam-wave interaction is proposed. Here, the beam echo harmonic effect is applied to a traveling wave tube like device. The scheme is configured as a combination of a frequency multiplier and amplifier with, for instance, W-band (millimeter wave) input signals and terahertz output power. A one-dimensional model of this device shows that a 10th order harmonic-wave can be generated while other harmonic waves are suppressed. The device only requires a readily available input source (W-band), and the output frequency can be tuned continuously over a wide band.
Nonrelativistic D3-brane in the presence of higher derivative corrections
NASA Astrophysics Data System (ADS)
Ghodsi, Ahmad; Alishahiha, Mohsen
2009-07-01
Using α'3 terms of type IIB supergravity action we study higher order corrections to the nonrelativistic nonextremal D3-brane. Utilizing the corrected solution we evaluate corrections to temperature, entropy, and shear viscosity. We also compute the η/s ratio which although within the range of validity of the supergravity approximation and in the lowest order of the correction the universal bound is respected, there is a possibility for a violation of the bound when higher terms in the expansion are taken into account.
The equation of motion of an electron : a debate in classical and quantum physics.
Kim, K.-J.
1999-01-27
The current status of understanding of the equation of motion of an electron is summarized. Classically, a consistent, linearized theory exists for an electron of finite extent, as long as the size of the electron is larger than the classical electron radius. Nonrelativistic quantum mechanics seems to offer a tine theory even in the point-particle limit.
SIMULATIONS AND THEORY OF ION INJECTION AT NON-RELATIVISTIC COLLISIONLESS SHOCKS
Caprioli, Damiano; Pop, Ana-Roxana; Spitkovsky, Anatoly
2015-01-10
We use kinetic hybrid simulations (kinetic ions-fluid electrons) to characterize the fraction of ions that are accelerated to non-thermal energies at non-relativistic collisionless shocks. We investigate the properties of the shock discontinuity and show that shocks propagating almost along the background magnetic field (quasi-parallel shocks) reform quasi-periodically on ion cyclotron scales. Ions that impinge on the shock when the discontinuity is the steepest are specularly reflected. This is a necessary condition for being injected, but it is not sufficient. Also, by following the trajectories of reflected ions, we calculate the minimum energy needed for injection into diffusive shock acceleration, as a function of the shock inclination. We construct a minimal model that accounts for the ion reflection from quasi-periodic shock barrier, for the fraction of injected ions, and for the ion spectrum throughout the transition from thermal to non-thermal energies. This model captures the physics relevant for ion injection at non-relativistic astrophysical shocks with arbitrary strengths and magnetic inclinations, and represents a crucial ingredient for understanding the diffusive shock acceleration of cosmic rays.
Correlations between bulk parameters in relativistic and nonrelativistic hadronic mean-field models
NASA Astrophysics Data System (ADS)
Santos, B. M.; Dutra, M.; Lourenço, O.; Delfino, A.
2015-07-01
In this work, we study the arising of correlations among some isoscalar (Ko, Qo, and Io) and isovector (J , Lo, Ksymo, Qsymo, and Isymo) bulk parameters in nonrelativistic and relativistic hadronic mean-field models. For the former, we investigate correlations in Skyrme and Gogny parametrizations, as well as in the nonrelativistic (NR) limit of relativistic point-coupling models. We provide analytical correlations among bulk parameters for the NR limit, discussing the conditions in which they are linear ones. Based on a recent study [Santos et al., Phys. Rev. C 90, 035203 (2014), 10.1103/PhysRevC.90.035203], we also show that some correlations presented in the NR limit are reproduced for relativistic models presenting cubic and quartic self-interactions in the scalar field σ , mostly studied in this work in the context of the relativistic framework. We also discuss how the crossing points, observed in the density dependence of some bulk parameters, can be seen as a signature of linear correlations between the specific bulk quantity presenting the crossing and its immediately next order parameter.
Park, Jaehong; Caprioli, Damiano; Spitkovsky, Anatoly
2015-02-27
We study diffusive shock acceleration (DSA) of protons and electrons at nonrelativistic, high Mach number, quasiparallel, collisionless shocks by means of self-consistent 1D particle-in-cell simulations. For the first time, both species are found to develop power-law distributions with the universal spectral index -4 in momentum space, in agreement with the prediction of DSA. We find that scattering of both protons and electrons is mediated by right-handed circularly polarized waves excited by the current of energetic protons via nonresonant hybrid (Bell) instability. Protons are injected into DSA after a few gyrocycles of shock drift acceleration (SDA), while electrons are first preheated via SDA, then energized via a hybrid acceleration process that involves both SDA and Fermi-like acceleration mediated by Bell waves, before eventual injection into DSA. Using the simulations we can measure the electron-proton ratio in accelerated particles, which is of paramount importance for explaining the cosmic ray fluxes measured on Earth and the multiwavelength emission of astrophysical objects such as supernova remnants, radio supernovae, and galaxy clusters. We find the normalization of the electron power law is ≲10^{-2} of the protons for strong nonrelativistic shocks.
Mahmood, S.; Sadiq, Safeer; Haque, Q.
2013-12-15
Linear and nonlinear electrostatic waves in magnetized dense electron-ion plasmas are studied with nonrelativistic and ultra-relativistic degenerate and singly, doubly charged helium (He{sup +}, He{sup ++}) and hydrogen (H{sup +}) ions, respectively. The dispersion relation of electrostatic waves in magnetized dense plasmas is obtained under both the energy limits of degenerate electrons. Using reductive perturbation method, the Zakharov-Kuznetsov equation for nonlinear propagation of electrostatic solitons in magnetized dense plasmas is derived for both nonrelativistic and ultra-relativistic degenerate electrons. It is found that variations in plasma density, magnetic field intensity, different mass, and charge number of ions play significant role in the formation of electrostatic solitons in magnetized dense plasmas. The numerical plots are also presented for illustration using the parameters of dense astrophysical plasma situations such as white dwarfs and neutron stars exist in the literature. The present investigation is important for understanding the electrostatic waves propagation in the outer periphery of compact stars which mostly consists of hydrogen and helium ions with degenerate electrons in dense magnetized plasmas.
Dieckmann, M. E.; Ahmed, H.; Sarri, G.; Doria, D.; Kourakis, I.; Borghesi, M.; Romagnani, L.; Pohl, M.
2013-04-15
Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.
The Nonrelativistic Evolution of GRBs 980703 and 970508: Beaming-independent Calorimetry
NASA Astrophysics Data System (ADS)
Berger, E.; Kulkarni, S. R.; Frail, D. A.
2004-09-01
We use the Sedov-Taylor self-similar solution to model the radio emission from the γ-ray bursts GRB 980703 and GRB 970508 when the blast wave has decelerated to nonrelativistic velocities. This approach allows us to infer the energy of the GRBs independent of jet collimation. We find that for GRB 980703 the kinetic energy at the time of the transition to nonrelativistic evolution, tNR~40 days, is EST~(1-6)×1051 ergs. For GRB 970508 we find EST~3×1051 ergs at tNR~100 days, nearly an order of magnitude higher than the energy formerly derived by Frail, Waxman, and Kulkarni. This is due primarily to revised cosmological parameters and partly to the maximum likelihood fit we use here. Taking into account radiative losses prior to tNR, the inferred energies agree well with those derived from the early, relativistic evolution of the afterglow. Thus, the analysis presented here provides a robust, geometry-independent confirmation that the energy scale of cosmological GRBs is about 5×1051 ergs and also shows that the central engine in these two bursts did not produce a significant amount of energy in mildly relativistic ejecta at late times. Furthermore, a comparison to the prompt energy release reveals a wide dispersion in the γ-ray efficiency, strengthening our growing understanding that Eγ is a not a reliable proxy for the total energy.
Quantum chaos inside space-temporal Sinai billiards
NASA Astrophysics Data System (ADS)
Addazi, Andrea
2016-04-01
We discuss general aspects of non-relativistic quantum chaos theory of scattering of a quantum particle on a system of a large number of naked singularities. We define such a system space-temporal Sinai billiard. We discuss the problem in semiclassical approach. We show that in semiclassical regime the formation of trapped periodic semiclassical orbits inside the system is unavoidable. This leads to general expression of survival probabilities and scattering time delays, expanded to the chaotic Pollicott-Ruelle resonances. Finally, we comment on possible generalizations of these aspects to relativistic quantum field theory.
Quantum features of natural cellular automata
NASA Astrophysics Data System (ADS)
Elze, Hans-Thomas
2016-03-01
Cellular automata can show well known features of quantum mechanics, such as a linear rule according to which they evolve and which resembles a discretized version of the Schrödinger equation. This includes corresponding conservation laws. The class of “natural” Hamiltonian cellular automata is based exclusively on integer-valued variables and couplings and their dynamics derives from an Action Principle. They can be mapped reversibly to continuum models by applying Sampling Theory. Thus, “deformed” quantum mechanical models with a finite discreteness scale l are obtained, which for l → 0 reproduce familiar continuum results. We have recently demonstrated that such automata can form “multipartite” systems consistently with the tensor product structures of nonrelativistic many-body quantum mechanics, while interacting and maintaining the linear evolution. Consequently, the Superposition Principle fully applies for such primitive discrete deterministic automata and their composites and can produce the essential quantum effects of interference and entanglement.
Magnetically driven quantum heat engine
NASA Astrophysics Data System (ADS)
Munoz, Enrique; Pena, Francisco
2015-03-01
In analogy with classical thermodynamics, a quantum heat engine generates useful mechanical work from heat, by means of a reversible sequence of transformations (trajectories), where the ``working substance'' is of quantum mechanical nature. Several theoretical implementations for a quantum heat engine have been discussed in the literature, such as entangled states in a qubit, quantum mechanical versions of the Otto cycle, and photocells. In this work, we propose yet a different alternative by introducing the concept of a magnetically driven quantum heat engine. We studied the efficiency of such system, by considering as the ``working substance'' a single nonrelativistic particle trapped in a cylindrical potential well, as a model for a semiconductor quantum dot, in the presence of an external magnetic field. The trajectories are driven by a quasistatic modulation of the external magnetic-field intensity, while the system is in contact with macroscopic thermostats. The external magnetic field modulation allows to modify the effective geometric confinement, in analogy with a piston in a classical gas. E. Munoz acknowledges financial support from Fondecyt under Contract 1141146.
Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas.
Masood, Waqas; Eliasson, Bengt; Shukla, Padma K
2010-06-01
A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin- 1/2, and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin- 1/2 contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars. PMID:20866534
Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas.
Masood, Waqas; Eliasson, Bengt; Shukla, Padma K
2010-06-01
A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin- 1/2, and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin- 1/2 contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars.
Huygens' principle, the free Schrödinger particle and the quantum anti-centrifugal force
NASA Astrophysics Data System (ADS)
Cirone, M. A.; Dahl, J. P.; Fedorov, M.; Greenberger, D.; Schleich, W. P.
2002-01-01
Huygens' principle following from the d'Alembert wave equation is not valid in two-dimensional space. A Schrödinger particle of vanishing angular momentum moving freely in two dimensions experiences an attractive force - the quantum anti-centrifugal force - towards its centre. We connect these two phenomena by comparing and contrasting the radial propagators of the d'Alembert wave equation and of a free non-relativistic quantum mechanical particle in two and three dimensions.
NASA Astrophysics Data System (ADS)
Golden, Sidney
1995-02-01
As characterized experimentally by Rutherford, an essential feature of radioactive decompositions is their being constituted of randomly occurring events in terms of which the decomposing systems exhibit exponential temporal decay behavior with associated characteristic half-lives. This feature is rigorously accounted for generally by the recent temporally-quantized dynamical theory of strictly-irreversible evolution of isolated and localized non-relativistic quantum systems, which theory also obviates the celebrated Zeno's paradox of conventional quantum theory.
Feynman's simple quantum mechanics
NASA Astrophysics Data System (ADS)
Taylor, Edwin F.
1997-03-01
This sample class presents an alternative to the conventional introduction to quantum mechanics and describes its current use in a credit course. This alternative introduction rests on theory presented in professional and popular writings by Richard Feynman. Feynman showed that Nature gives a simple command to the electron: "Explore all paths." All of nonrelativistic quantum mechanics, among other fundamental results, comes from this command. With a desktop computer the student points and clicks to tell a modeled electron which paths to follow. The computer then shows the results, which embody the elemental strangeness and paradoxical behaviors of the world of the very small. Feynman's approach requires few equations and provides a largely non-mathematical introduction to the wave function of conventional quantum mechanics. Draft software and materials already used for two semesters in an e-mail computer conference credit university course show that Feynman's approach works well with a variety of students. The sample class explores computer and written material and describes the next steps in its development.
Three Attempts at Two Axioms for Quantum Mechanics
NASA Astrophysics Data System (ADS)
Rohrlich, Daniel
The axioms of nonrelativistic quantum mechanics lack clear physical meaning. In particular, they say nothing about nonlocality. Yet quantum mechanics is not only nonlocal, it is twice nonlocal: there are nonlocal quantum correlations, and there is the Aharonov-Bohm effect, which implies that an electric or magnetic field here may act on an electron there. Can we invert the logical hierarchy? That is, can we adopt nonlocality as an axiom for quantum mechanics and derive quantum mechanics from this axiom and an additional axiom of causality? Three versions of these two axioms lead to three different theories, characterized by "maximal nonlocal correlations", "jamming" and "modular energy". Where is quantum mechanics in these theories?
Polymer quantum mechanics some examples using path integrals
Parra, Lorena; Vergara, J. David
2014-01-14
In this work we analyze several physical systems in the context of polymer quantum mechanics using path integrals. First we introduce the group averaging method to quantize constrained systems with path integrals and later we use this procedure to compute the effective actions for the polymer non-relativistic particle and the polymer harmonic oscillator. We analyze the measure of the path integral and we describe the semiclassical dynamics of the systems.
Quantum chaos in QCD and hadrons
NASA Astrophysics Data System (ADS)
Markum, Harald; Plessas, Willibald; Pullirsch, Rainer; Sengl, Bianka; Wagenbrunn, Robert F.
This article starts with an introduction into quantum chaos and its relationship to classical chaos. The Bohigas-Giannoni-Schmit conjecture is formulated and evaluated within the random-matrix theory. The objective of the presentation is twofold and begins with recent results on quantum chromodynamics and the quarkgluon plasma. We conclude with recent research work on the spectroscopy of baryons. Within the framework of a relativistic constituent quark model we investigate the excitation spectra of the nucleon and the delta with regard to a possible chaotic behavior for the cases when a hyperfine interaction of either Goldstone-boson-exchange or one-gluon-exchange type is added to the confinement interaction. Agreement with the experimental hadron spectrum is established.
NASA Astrophysics Data System (ADS)
Cardall, Christian Y.; Budiardja, Reuben D.; Endeve, Eirik; Mezzacappa, Anthony
2014-02-01
GenASiS (General Astrophysical Simulation System) is a new code being developed initially and primarily, though by no means exclusively, for the simulation of core-collapse supernovae on the world's leading capability supercomputers. This paper—the first in a series—demonstrates a centrally refined coordinate patch suitable for gravitational collapse and documents methods for compressible nonrelativistic hydrodynamics. We benchmark the hydrodynamics capabilities of GenASiS against many standard test problems; the results illustrate the basic competence of our implementation, demonstrate the strengths and limitations of the HLLC relative to the HLL Riemann solver in a number of interesting cases, and provide preliminary indications of the code's ability to scale and to function with cell-by-cell fixed-mesh refinement.
Can Nonrelativistic QCD Explain the γ γ*→ηc Transition Form Factor Data?
NASA Astrophysics Data System (ADS)
Feng, Feng; Jia, Yu; Sang, Wen-Long
2015-11-01
Unlike the bewildering situation in the γ γ*→π form factor, a widespread view is that perturbative QCD can decently account for the recent BABAR measurement of the γ γ*→ηc transition form factor. The next-to-next-to-leading-order perturbative correction to the γ γ*→ηc ,b form factor, is investigated in the nonrelativistic QCD (NRQCD) factorization framework for the first time. As a byproduct, we obtain, by far, the most precise order-αs2 NRQCD matching coefficient for the ηc ,b→γ γ process. After including the substantial negative order-αs2 correction, the good agreement between NRQCD prediction and the measured γ γ*→ηc form factor is completely ruined over a wide range of momentum transfer squared. This eminent discrepancy casts some doubts on the applicability of the NRQCD approach to hard exclusive reactions involving charmonium.
Solar He-3-rich events and non-relativistic electron events: A new association
NASA Technical Reports Server (NTRS)
Reames, D. V.; Vonrosenvinge, T. T.; Lin, R. P.
1984-01-01
In 15 months of observation by the ISEE-e spacecraft, it was found that virtually all solar greater than or approximately equal to 1.3 MeV/nucleon He-3-rich events are associated with impulsive 2 to approximately 100 keV electron events, although many electron events were not accompanied by detectable He-3 increases. Both the He-3 and the electrons exhibit nearly scatter-free propagation in the interplanetary medium, and the times of onset and maximum for the He-3 and electron increases are closely related by velocity dispertion. The electron events and their related type III solar radio bursts provide, for the first time, identification of the flares which produce He-3-rich events. He-3 appears to be accelerated at the flash phase of solar flares along with nonrelativistic electrons.
Cho; Lee; Kim
2000-04-01
Nonrelativistic electromagnetic surface waves propagating on the plane interface between dusty electron-positron plasma and vacuum are investigated by specular reflection procedure. In the presence of an applied magnetic field (B(0)=B(0)yinsertion mark) directed perpendicular to both the interface normal and the wave vector, transverse electromagnetic modes are studied in terms of the dispersion relation. The analytic modes are derived and discussed with the aid of some numerical analysis. The cold electromagnetic surface wave dispersion relation considering the effect of dust particle shows that possible modes appear only when the normalized frequency (omega;) and the wave vector (&Kmacr;) satisfy the condition Omega;
Complete Nonrelativistic-QCD Prediction for Prompt Double J /ψ Hadroproduction
NASA Astrophysics Data System (ADS)
He, Zhi-Guo; Kniehl, Bernd A.
2015-07-01
We perform a complete study of prompt double J /ψ hadroproduction at leading order in the nonrelativistic-QCD factorization framework by including all possible pairings of the c c ¯ Fock states 1S0[8] , 3S1[1,8] , and 3PJ[1,8] with J =0 ,1 ,2 . We find that the 1S0[8] and 3PJ[8] channels of J /ψ and ψ' production and the 3PJ[1] and 3S1[8] channels of χc J production, which have been overlooked so far, greatly dominate at large invariant masses and rapidity separations of the J /ψ pair, and that their inclusion nearly fills the large gap between previous incomplete predictions within the color-singlet model and the recent measurement by the CMS Collaboration at the CERN LHC, leaving room for next-to-leading-order corrections of typical size.
NASA Astrophysics Data System (ADS)
Cotner, Eric
2016-09-01
Scalar particles are a common prediction of many beyond the Standard Model theories. If they are light and cold enough, there is a possibility they may form Bose-Einstein condensates, which will then become gravitationally bound. These boson stars are solitonic solutions to the Einstein-Klein-Gordon equations but may be approximated in the nonrelativistic regime with a coupled Schrödinger-Poisson system. General properties of single soliton states are derived, including the possibility of quartic self-interactions. Binary collisions between two solitons are then studied, and the effects of different mass ratios, relative phases, self-couplings, and separation distances are characterized, leading to an easy conceptual understanding of how these parameters affect the collision outcome in terms of conservation of energy. Applications to dark matter are discussed.
ϒ (n S ) and χb(n P ) production at hadron colliders in nonrelativistic QCD
NASA Astrophysics Data System (ADS)
Han, Hao; Ma, Yan-Qing; Meng, Ce; Shao, Hua-Sheng; Zhang, Yu-Jie; Chao, Kuang-Ta
2016-07-01
ϒ (n S ) and χb(n P ) (n =1 , 2, 3) production at the LHC is studied at next-to-leading order in αs in nonrelativistic QCD. Feeddown contributions from higher χb and ϒ states are all considered for lower ϒ cross sections and polarizations. The long distance matrix elements (LDMEs) are extracted from the yield data, and then used to make predictions for the ϒ (n S ) polarizations, which are found to be consistent with the measured polarization data within errors. In particular, the ϒ (3 S ) polarization puzzle can be understood by a large feeddown contribution from χb(3 P ) states. Our results may provide a good description for both cross sections and polarizations of prompt ϒ (n S ) and χb(n P ) production at the LHC.
Injection and propagation of a nonrelativistic electron beam and spacecraft charging
Okuda, H.; Berchem, J.
1987-05-01
Two-dimensional numerical simulations have been carried out in order to study the injection and propagation of a nonrelativistic electron beam from a spacecraft into a fully ionized plasma in a magnetic field. Contrary to the earlier results in one-dimension, a high density electron beam whose density is comparable to the ambient density can propagate into a plasma. A strong radial electric field resulting from the net charges in the beam causes the beam electrons to spread radially reducing the beam density. When the injection current exceeds the return current, significant charging of the spacecraft is observed along with the reflection of the injected electrons back to the spacecraft. Recent data on the electron beam injection from the Spacelab 1 (SEPAC) are discussed.
Simulations of ion acceleration at non-relativistic shocks. II. Magnetic field amplification
Caprioli, D.; Spitkovsky, A.
2014-10-10
We use large hybrid simulations to study ion acceleration and generation of magnetic turbulence due to the streaming of particles that are self-consistently accelerated at non-relativistic shocks. When acceleration is efficient, we find that the upstream magnetic field is significantly amplified. The total amplification factor is larger than 10 for shocks with Alfvénic Mach number M = 100, and scales with the square root of M. The spectral energy density of excited magnetic turbulence is determined by the energy distribution of accelerated particles, and for moderately strong shocks (M ≲ 30) agrees well with the prediction of resonant streaming instability, in the framework of quasilinear theory of diffusive shock acceleration. For M ≳ 30, instead, Bell's non-resonant hybrid (NRH) instability is predicted and found to grow faster than resonant instability. NRH modes are excited far upstream by escaping particles, and initially grow without disrupting the current, their typical wavelengths being much shorter than the current ions' gyroradii. Then, in the nonlinear stage, most unstable modes migrate to larger and larger wavelengths, eventually becoming resonant in wavelength with the driving ions, which start diffuse. Ahead of strong shocks we distinguish two regions, separated by the free-escape boundary: the far upstream, where field amplification is provided by the current of escaping ions via NRH instability, and the shock precursor, where energetic particles are effectively magnetized, and field amplification is provided by the current in diffusing ions. The presented scalings of magnetic field amplification enable the inclusion of self-consistent microphysics into phenomenological models of ion acceleration at non-relativistic shocks.
Quantum simulation of the Dirac equation.
Gerritsma, R; Kirchmair, G; Zähringer, F; Solano, E; Blatt, R; Roos, C F
2010-01-01
The Dirac equation successfully merges quantum mechanics with special relativity. It provides a natural description of the electron spin, predicts the existence of antimatter and is able to reproduce accurately the spectrum of the hydrogen atom. The realm of the Dirac equation-relativistic quantum mechanics-is considered to be the natural transition to quantum field theory. However, the Dirac equation also predicts some peculiar effects, such as Klein's paradox and 'Zitterbewegung', an unexpected quivering motion of a free relativistic quantum particle. These and other predicted phenomena are key fundamental examples for understanding relativistic quantum effects, but are difficult to observe in real particles. In recent years, there has been increased interest in simulations of relativistic quantum effects using different physical set-ups, in which parameter tunability allows access to different physical regimes. Here we perform a proof-of-principle quantum simulation of the one-dimensional Dirac equation using a single trapped ion set to behave as a free relativistic quantum particle. We measure the particle position as a function of time and study Zitterbewegung for different initial superpositions of positive- and negative-energy spinor states, as well as the crossover from relativistic to non-relativistic dynamics. The high level of control of trapped-ion experimental parameters makes it possible to simulate textbook examples of relativistic quantum physics. PMID:20054392
ERIC Educational Resources Information Center
Hassett, Dawnene D.
2006-01-01
Currently, definitions of "science", "reading", and "literacy" in the US lend a seemingly nonrelativistic permanence to these terms, and render them resistant to critique. This paper offers a theoretical frame for critiquing this permanence, analysing why early-literacy instruction is tightly tied to traditional forms of print literacy, focusing…
Cheng, Lan
2015-08-14
Quantum-chemical computations of nuclear quadrupole-coupling parameters for 24 open-shell states of small molecules based on non-relativistic and spin-free exact two-component (SFX2C) relativistic equation-of-motion coupled-cluster (EOM-CC) as well as spin-orbital-based restricted open-shell Hartree-Fock coupled-cluster (ROHF-CC) methods are reported. Relativistic effects, the performance of the EOM-CC and ROHF-CC methods for treating electron correlation, as well as basis-set convergence have been carefully analyzed. Consideration of relativistic effects is necessary for accurate calculations on systems containing third-row (K-Kr) and heavier elements, as expected, and the SFX2C approach is shown to be a useful cost-effective option here. Further, it is demonstrated that the EOM-CC methods constitute flexible and accurate alternatives to the ROHF-CC methods in the calculations of nuclear quadrupole-coupling parameters for open-shell states.
Less Interpretation and More Decoherence in Quantum Gravity and Inflationary Cosmology
NASA Astrophysics Data System (ADS)
Crull, Elise M.
2015-09-01
I argue that quantum decoherence—understood as a dynamical process entailed by the standard formalism alone—carries us beyond conceptual aspects of non-relativistic quantum mechanics deemed insurmountable by many contributors to the recent quantum gravity and cosmology literature. These aspects include various incarnations of the measurement problem and of the quantum-to-classical puzzle. Not only can such problems be largely bypassed or dissolved without default to a particular interpretation, but theoretical work in relativistic arenas stands to gain substantial physical and philosophical insight by incorporating decoherence phenomena.
Quantum Larmor radiation in de Sitter spacetime
NASA Astrophysics Data System (ADS)
Blaga, Robert; Busuioc, Sergiu
2016-09-01
We study the radiation emitted by inertial charge evolving on the expanding de Sitter spacetime. Performing a perturbative calculation, within scalar quantum electrodynamics (sQED), we obtain the transition amplitude for the process and using this we define the energy radiated by the source. In the non-relativistic limit we find that the leading term is compatible with the classical result (Larmor formula). The first quantum correction is found to be negative, a result which is in line with a number of similar quantum field theory results. For the ultra-relativistic case we find a logarithmic divergence of the emitted energy for large frequencies, which we link to the nature of the spacetime. We compare our results with that of Nomura et al. (JCAP 11:013, 2006), where the authors make a similar calculation for a general conformally flat spacetime.
Electron exchange-correlation in quantum mechanics
Ritchie, B
2009-01-30
It is shown that Fermi-Dirac statistics is guaranteed by the Dirac current, from which spin-dependent quantum velocity fields and spin-dependent quantum trajectories can be inferred. Pauli's exclusion principle is demonstrated using the spin-dependent quantum trajectories. The Dirac current, unlike the Schroedinger current, is nonzero for stationary bound states due to the permanent magnetic moment of the electron. It is of order c{sup 0} in agreement with observation that Fermi-Dirac statistics is independent of electronic velocity. In summary the physical basis for exchange-correlation is found in Dirac's equation, although Schroedinger's equation may be used to evaluate the Dirac current in the nonrelativistic regime of electronic velocity.
Accurate Energy Spectrum for the Quantum Yang-Mills Mechanics with Nonlinear Color Oscillations
NASA Astrophysics Data System (ADS)
Pedram, Pouria
2015-01-01
Yang-Mills theory as the foundation for quantum chromodynamics is a non-Abelian gauge theory with self-interactions between vector particles. Here, we study the Yang-Mills Hamiltonian with nonlinear color oscillations in the absence of external sources corresponding to the group SU(2). In the quantum domain, we diagonalize the Hamiltonian using the optimized trigonometric basis expansion method and find accurate energy eigenvalues and eigenfunctions for one and two degrees of freedom. We also compare our results with the semiclassical solutions.
Quantum theory and chemistry: Two propositions
NASA Technical Reports Server (NTRS)
Aronowitz, S.
1980-01-01
Two propositions concerning quantum chemistry are proposed. First, it is proposed that the nonrelativistic Schroedinger equation, where the Hamiltonian operator is associated with an assemblage of nuclei and electrons, can never be arranged to yield specific molecules in the chemists' sense. It is argued that this result is a necessary condition if the Schroedinger has relevancy to chemistry. Second, once a system is in a particular state with regard to interactions among its components (the assemblage of nuclei and electrons), it cannot spontaneously eliminate any of those interactions. This leads to a subtle form of irreversibility.
A hydrodynamical model for relativistic spin quantum plasmas
Asenjo, Felipe A.; Munoz, Victor; Valdivia, J. Alejandro; Mahajan, Swadesh M.
2011-01-15
Based on the one-body particle-antiparticle Dirac theory of electrons, a set of relativistic quantum fluid equations for a spin half plasma is derived. The particle-antiparticle nature of the relativistic particles is explicit in this fluid theory, which also includes quantum effects such as spin. The nonrelativistic limit is shown to be in agreement with previous attempts to develop a spin plasma theory derived from the Pauli Hamiltonian. Harnessing the formalism to the study of electromagnetic mode propagation, conceptually new phenomena are revealed; the particle-antiparticle effects increase the fluid opacity to these waves, while the spin effects tend to make the fluid more transparent.
Yannouleas, Constantine; Romanovsky, Igor; Landman, Uzi
2015-01-01
Graphene's isolation launched explorations of fundamental relativistic physics originating from the planar honeycomb lattice arrangement of the carbon atoms, and of potential technological applications in nanoscale electronics. Bottom-up fabricated atomically-precise segmented graphene nanoribbons, SGNRs, open avenues for studies of electrical transport, coherence, and interference effects in metallic, semiconducting, and mixed GNRs, with different edge terminations. Conceptual and practical understanding of electric transport through SGNRs is gained through nonequilibrium Green's function (NEGF) conductance calculations and a Dirac continuum model that absorbs the valence-to-conductance energy gaps as position-dependent masses, including topological-in-origin mass-barriers at the contacts between segments. The continuum model reproduces the NEGF results, including optical Dirac Fabry-Prot (FP) equidistant oscillations for massless relativistic carriers in metallic armchair SGNRs, and an unequally-spaced FP pattern for mixed armchair-zigzag SGNRs where carriers transit from a relativistic (armchair) to a nonrelativistic (zigzag) regime. This provides a unifying framework for analysis of coherent transport phenomena and interpretation of forthcoming experiments in SGNRs. PMID:25599915
Accurate nonrelativistic ground-state energies of 3d transition metal atoms
Scemama, A.; Applencourt, T.; Giner, E.; Caffarel, M.
2014-12-28
We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) method and including the most prominent determinants of the full configuration interaction expansion are used as trial wavefunctions. Using a maximum of a few tens of thousands determinants, fixed-node errors on total DMC energies are found to be greatly reduced for some atoms with respect to those obtained with Hartree-Fock nodes. To the best of our knowledge, the FN-DMC/(CIPSI nodes) ground-state energies presented here are the lowest variational total energies reported so far. They differ from the recently recommended non-variational values of McCarthy and Thakkar [J. Chem. Phys. 136, 054107 (2012)] only by a few percents of the correlation energy. Thanks to the variational property of FN-DMC total energies, our results provide exact lower bounds for the absolute value of all-electron correlation energies, |E{sub c}|.
Yannouleas, Constantine; Romanovsky, Igor; Landman, Uzi
2015-01-20
Graphene's isolation launched explorations of fundamental relativistic physics originating from the planar honeycomb lattice arrangement of the carbon atoms, and of potential technological applications in nanoscale electronics. Bottom-up fabricated atomically-precise segmented graphene nanoribbons, SGNRs, open avenues for studies of electrical transport, coherence, and interference effects in metallic, semiconducting, and mixed GNRs, with different edge terminations. Conceptual and practical understanding of electric transport through SGNRs is gained through nonequilibrium Green's function (NEGF) conductance calculations and a Dirac continuum model that absorbs the valence-to-conductance energy gaps as position-dependent masses, including topological-in-origin mass-barriers at the contacts between segments. The continuum model reproduces themore » NEGF results, including optical Dirac Fabry-Pérot (FP) equidistant oscillations for massless relativistic carriers in metallic armchair SGNRs, and an unequally-spaced FP pattern for mixed armchair-zigzag SGNRs where carriers transit from a relativistic (armchair) to a nonrelativistic (zigzag) regime. This provides a unifying framework for analysis of coherent transport phenomena and interpretation of forthcoming experiments in SGNRs.« less
Yannouleas, Constantine; Romanovsky, Igor; Landman, Uzi
2015-01-20
Graphene's isolation launched explorations of fundamental relativistic physics originating from the planar honeycomb lattice arrangement of the carbon atoms, and of potential technological applications in nanoscale electronics. Bottom-up fabricated atomically-precise segmented graphene nanoribbons, SGNRs, open avenues for studies of electrical transport, coherence, and interference effects in metallic, semiconducting, and mixed GNRs, with different edge terminations. Conceptual and practical understanding of electric transport through SGNRs is gained through nonequilibrium Green's function (NEGF) conductance calculations and a Dirac continuum model that absorbs the valence-to-conductance energy gaps as position-dependent masses, including topological-in-origin mass-barriers at the contacts between segments. The continuum model reproduces the NEGF results, including optical Dirac Fabry-Pérot (FP) equidistant oscillations for massless relativistic carriers in metallic armchair SGNRs, and an unequally-spaced FP pattern for mixed armchair-zigzag SGNRs where carriers transit from a relativistic (armchair) to a nonrelativistic (zigzag) regime. This provides a unifying framework for analysis of coherent transport phenomena and interpretation of forthcoming experiments in SGNRs.
Nonrelativistic Chern-Simons theories and three-dimensional Hořava-Lifshitz gravity
NASA Astrophysics Data System (ADS)
Hartong, Jelle; Lei, Yang; Obers, Niels A.
2016-09-01
We show that certain three-dimensional Hořava-Lifshitz gravity theories can be written as Chern-Simons gauge theories on various nonrelativistic algebras. The algebras are specific extensions of the Bargmann, Newton-Hooke and Schrödinger algebras each of which has the Galilean algebra as a subalgebra. To show this we employ the fact that Hořava-Lifshitz gravity corresponds to dynamical Newton-Cartan geometry. In particular, the extended Bargmann (Newton-Hooke) Chern-Simons theory corresponds to projectable Hořava-Lifshitz gravity with a local U (1 ) gauge symmetry without (with) a cosmological constant. Moreover we identify an extended Schrödinger algebra containing three extra generators that are central with respect to the subalgebra of Galilean boosts, momenta and rotations, for which the Chern-Simons theory gives rise to a novel version of nonprojectable conformal Hořava-Lifshitz gravity that we refer to as Chern-Simons Schrödinger gravity. This theory has a z =2 Lifshitz geometry as a vacuum solution and thus provides a new framework to study Lifshitz holography.
NASA Astrophysics Data System (ADS)
Niemiec, Jacek; Bohdan, Artem; Kobzar, Oleh; Pohl, Martin
2016-06-01
Results of recent kinetic two-dimensional particle-in-cell studies of high Mach-number nonrelativistic perpendicular shocks with applications to young supernova remnants are reported. These new large-scale simulations sample a representative portion of the shock surface to fully account for timedependent effects. They are performed for different orientations of the average large-scale magnetic field with respect to the 2D simulation plane to allow an insight into the 3D physics. We discuss the nonlinear shock structure and particle energization processes with emphasis on the dynamics on electron heating and pre-acceleration needed for their injection into diffusive shock acceleration. To this end we investigate the microphysics of electron acceleration during spontaneous turbulent magnetic reconnection at the shock ramp and compare the efficiency of these processes to electron energization resulting from their interactions with electrostatic Buneman modes in the shock foot. The influence of the global shock front nonstationarity effects such as the shock rippling and self-reformation is also discussed.
Complete Nonrelativistic-QCD Prediction for Prompt Double J/ψ Hadroproduction.
He, Zhi-Guo; Kniehl, Bernd A
2015-07-10
We perform a complete study of prompt double J/ψ hadroproduction at leading order in the nonrelativistic-QCD factorization framework by including all possible pairings of the cc̅ Fock states (1)S(0)([8]), (3)S(1)([1,8]), and (3)P(J)([1,8]) with J=0,1,2. We find that the (1)S(0)([8]) and (3)P(J)([8]) channels of J/ψ and ψ'} production and the (3)P(J)([1]) and (3)S(1)([8]) channels of χ(cJ) production, which have been overlooked so far, greatly dominate at large invariant masses and rapidity separations of the J/ψ pair, and that their inclusion nearly fills the large gap between previous incomplete predictions within the color-singlet model and the recent measurement by the CMS Collaboration at the CERN LHC, leaving room for next-to-leading-order corrections of typical size.
Sims, James S.; Hagstrom, Stanley A.
2014-06-14
In a previous work, Sims and Hagstrom [“Hylleraas-configuration-interaction study of the 1 {sup 1}S ground state of neutral beryllium,” Phys. Rev. A 83, 032518 (2011)] reported Hylleraas-configuration-interaction (Hy-CI) method variational calculations for the {sup 1}S ground state of neutral beryllium with an estimated accuracy of a tenth of a microhartree. In this work, the calculations have been extended to higher accuracy and, by simple scaling of the orbital exponents, to the entire Be 2 {sup 1}S isoelectronic sequence. The best nonrelativistic energies for Be, B{sup +}, and C{sup ++} obtained are −14.6673 5649 269, −24.3488 8446 36, and −36.5348 5236 25 hartree, respectively. Except for Be, all computed nonrelativistic energies are superior to the known reference energies for these states.
Keenan, Brett D; Ford, Alexander L; Medvedev, Mikhail V
2015-09-01
Plasmas with electromagnetic fields turbulent at sub-Larmor scales are a feature of a wide variety of high-energy-density environments and are essential to the description of many astrophysical and laboratory plasma phenomena. Radiation from particles, whether they are relativistic or nonrelativistic, moving through small-scale magnetic turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation. The radiation, carrying information on the statistical properties of the magnetic turbulence, is also intimately related to the particle diffusive transport. We have investigated, both theoretically and numerically, the transport of nonrelativistic and trans-relativistic particles in plasmas with high-amplitude isotropic sub-Larmor-scale magnetic turbulence, and its relation to the spectra of radiation simultaneously produced by these particles. Consequently, the diffusive and radiative properties of plasmas turbulent on sub-Larmor scales may serve as a powerful tool to diagnosis laboratory and astrophysical plasmas.
Hu, Bin; Petela, Naomi; Kurze, Alexander; Chan, Kok-Lung; Chapard, Christophe; Nasmyth, Kim
2015-01-01
Sequencing DNA fragments associated with proteins following in vivo cross-linking with formaldehyde (known as ChIP-seq) has been used extensively to describe the distribution of proteins across genomes. It is not widely appreciated that this method merely estimates a protein's distribution and cannot reveal changes in occupancy between samples. To do this, we tagged with the same epitope orthologous proteins in Saccharomyces cerevisiae and Candida glabrata, whose sequences have diverged to a degree that most DNA fragments longer than 50 bp are unique to just one species. By mixing defined numbers of C. glabrata cells (the calibration genome) with S. cerevisiae samples (the experimental genomes) prior to chromatin fragmentation and immunoprecipitation, it is possible to derive a quantitative measure of occupancy (the occupancy ratio – OR) that enables a comparison of occupancies not only within but also between genomes. We demonstrate for the first time that this ‘internal standard’ calibration method satisfies the sine qua non for quantifying ChIP-seq profiles, namely linearity over a wide range. Crucially, by employing functional tagged proteins, our calibration process describes a method that distinguishes genuine association within ChIP-seq profiles from background noise. Our method is applicable to any protein, not merely highly conserved ones, and obviates the need for the time consuming, expensive, and technically demanding quantification of ChIP using qPCR, which can only be performed on individual loci. As we demonstrate for the first time in this paper, calibrated ChIP-seq represents a major step towards documenting the quantitative distributions of proteins along chromosomes in different cell states, which we term biological chromodynamics. PMID:26130708
Li, Shu-Shen; Long, Gui-Lu; Bai, Feng-Shan; Feng, Song-Lin; Zheng, Hou-Zhi
2001-01-01
Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization. PMID:11562459
NASA Astrophysics Data System (ADS)
Long, Andrew J.; Lunardini, Cecilia; Sabancilar, Eray
2014-08-01
We study the physics potential of the detection of the Cosmic Neutrino Background via neutrino capture on tritium, taking the proposed PTOLEMY experiment as a case study. With the projected energy resolution of Δ ~ 0.15 eV, the experiment will be sensitive to neutrino masses with degenerate spectrum, m1 simeq m2 simeq m3 = mν gtrsim 0.1 eV. These neutrinos are non-relativistic today; detecting them would be a unique opportunity to probe this unexplored kinematical regime. The signature of neutrino capture is a peak in the electron spectrum that is displaced by 2 mν above the beta decay endpoint. The signal would exceed the background from beta decay if the energy resolution is Δ lesssim 0.7 mν . Interestingly, the total capture rate depends on the origin of the neutrino mass, being ΓD simeq 4 and ΓM simeq 8 events per year (for a 100 g tritium target) for unclustered Dirac and Majorana neutrinos, respectively. An enhancement of the rate of up to Script O(1) is expected due to gravitational clustering, with the unique potential to probe the local overdensity of neutrinos. Turning to more exotic neutrino physics, PTOLEMY could be sensitive to a lepton asymmetry, and reveal the eV-scale sterile neutrino that is favored by short baseline oscillation searches. The experiment would also be sensitive to a neutrino lifetime on the order of the age of the universe and break the degeneracy between neutrino mass and lifetime which affects existing bounds.
Long, Andrew J.; Lunardini, Cecilia; Sabancilar, Eray E-mail: Cecilia.Lunardini@asu.edu
2014-08-01
We study the physics potential of the detection of the Cosmic Neutrino Background via neutrino capture on tritium, taking the proposed PTOLEMY experiment as a case study. With the projected energy resolution of Δ ∼ 0.15 eV, the experiment will be sensitive to neutrino masses with degenerate spectrum, m{sub 1} ≅ m{sub 2} ≅ m{sub 3} = m{sub ν} ∼> 0.1 eV. These neutrinos are non-relativistic today; detecting them would be a unique opportunity to probe this unexplored kinematical regime. The signature of neutrino capture is a peak in the electron spectrum that is displaced by 2 m{sub ν} above the beta decay endpoint. The signal would exceed the background from beta decay if the energy resolution is Δ ∼< 0.7 m{sub ν} . Interestingly, the total capture rate depends on the origin of the neutrino mass, being Γ{sup D} ≅ 4 and Γ{sup M} ≅ 8 events per year (for a 100 g tritium target) for unclustered Dirac and Majorana neutrinos, respectively. An enhancement of the rate of up to O(1) is expected due to gravitational clustering, with the unique potential to probe the local overdensity of neutrinos. Turning to more exotic neutrino physics, PTOLEMY could be sensitive to a lepton asymmetry, and reveal the eV-scale sterile neutrino that is favored by short baseline oscillation searches. The experiment would also be sensitive to a neutrino lifetime on the order of the age of the universe and break the degeneracy between neutrino mass and lifetime which affects existing bounds.
What Causes Scatter-free Transport of Non-relativistic Solar Electrons?
NASA Astrophysics Data System (ADS)
Tan, Lun C.; Reames, Donald V.; Ng, Chee K.; Shao, Xi; Wang, Linghua
2011-02-01
We have examined the cause of the scatter-free transport of non-relativistic solar electrons. Electron scatter-free transport events are compared with the diffusive transport event. The emphasis of our examination is on the energy dependence of electron angular distributions and the steepening of interplanetary magnetic field (IMF) power spectral densities (PSDs). Near and above the proton gyrofrequency, the effects of both R-mode (whistler) and L-mode (electromagnetic ion cyclotron, EMIC) waves need to be taken into account separately. The PSD spectral steepening due to the EMIC wave damping by solar-wind thermal ions becomes essential. In a fast-rise-fast-decay impulsive electron event we have observed such steepening, which significantly reduces PSD levels at frequencies above the proton gyrofrequency. The spectral steepening thus produced favors the occurrence of scatter-free transport of low-energy electrons. Consequently, within the Wind/3D Plasma and Energetic Particle Instrument/Silicon Semiconductor Telescope measured energy range (~25-500 keV), there appears to be an electron energy window, across which the scatter-free transport of lower energy electrons would change to the diffusive transport of higher energy electrons. We have observed such a change and found it is correlated with the occurrence of broken power-law spectra of electrons. Thus the connection between the transition from diffusive to scatter-free electron transport and the concurrent transition from high to low IMF PSD levels with corresponding breaks in the electron power-law energy spectrum and PSD spectrum has been recognized.
Simulations of ion acceleration at non-relativistic shocks. I. Acceleration efficiency
Caprioli, D.; Spitkovsky, A.
2014-03-10
We use two-dimensional and three-dimensional hybrid (kinetic ions-fluid electrons) simulations to investigate particle acceleration and magnetic field amplification at non-relativistic astrophysical shocks. We show that diffusive shock acceleration operates for quasi-parallel configurations (i.e., when the background magnetic field is almost aligned with the shock normal) and, for large sonic and Alfvénic Mach numbers, produces universal power-law spectra ∝p {sup –4}, where p is the particle momentum. The maximum energy of accelerated ions increases with time, and it is only limited by finite box size and run time. Acceleration is mainly efficient for parallel and quasi-parallel strong shocks, where 10%-20% of the bulk kinetic energy can be converted to energetic particles and becomes ineffective for quasi-perpendicular shocks. Also, the generation of magnetic turbulence correlates with efficient ion acceleration and vanishes for quasi-perpendicular configurations. At very oblique shocks, ions can be accelerated via shock drift acceleration, but they only gain a factor of a few in momentum and their maximum energy does not increase with time. These findings are consistent with the degree of polarization and the morphology of the radio and X-ray synchrotron emission observed, for instance, in the remnant of SN 1006. We also discuss the transition from thermal to non-thermal particles in the ion spectrum (supra-thermal region) and we identify two dynamical signatures peculiar of efficient particle acceleration, namely, the formation of an upstream precursor and the alteration of standard shock jump conditions.
Continuous wavelet transform in quantum field theory
NASA Astrophysics Data System (ADS)
Altaisky, M. V.; Kaputkina, N. E.
2013-07-01
We describe the application of the continuous wavelet transform to calculation of the Green functions in quantum field theory: scalar ϕ4 theory, quantum electrodynamics, and quantum chromodynamics. The method of continuous wavelet transform in quantum field theory, presented by Altaisky [Phys. Rev. D 81, 125003 (2010)] for the scalar ϕ4 theory, consists in substitution of the local fields ϕ(x) by those dependent on both the position x and the resolution a. The substitution of the action S[ϕ(x)] by the action S[ϕa(x)] makes the local theory into a nonlocal one and implies the causality conditions related to the scale a, the region causality [J. D. Christensen and L. Crane, J. Math. Phys. (N.Y.) 46, 122502 (2005)]. These conditions make the Green functions G(x1,a1,…,xn,an)=⟨ϕa1(x1)…ϕan(xn)⟩ finite for any given set of regions by means of an effective cutoff scale A=min(a1,…,an).
NASA Astrophysics Data System (ADS)
Auletta, Gennaro; Fortunato, Mauro; Parisi, Giorgio
2014-01-01
Introduction; Part I. Basic Features of Quantum Mechanics: 1. From classical mechanics to quantum mechanics; 2. Quantum observable and states; 3. Quantum dynamics; 4. Examples of quantum dynamics; 5. Density matrix; Part II. More Advanced Topics: 6. Angular momentum and spin; 7. Identical particles; 8. Symmetries and conservation laws; 9. The measurement problem; Part III. Matter and Light: 10. Perturbations and approximation methods; 11. Hydrogen and helium atoms; 12. Hydrogen molecular ion; 13. Quantum optics; Part IV. Quantum Information: State and Correlations: 14. Quantum theory of open systems; 15. State measurement in quantum mechanics; 16. Entanglement: non-separability; 17. Entanglement: quantum information; References; Index.
From Entropic Dynamics to Quantum Theory
Caticha, Ariel
2009-12-08
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.
Sapir, Nir; Waxman, Eli; Katz, Boaz
2013-09-01
The spectrum of radiation emitted following shock breakout from a star's surface with a power-law density profile {rho}{proportional_to}x{sup n} is investigated. Assuming planar geometry, local Compton equilibrium, and bremsstrahlung emission as the dominant photon production mechanism, numerical solutions are obtained for the photon number density and temperature profiles as a function of time for hydrogen-helium envelopes. The temperature solutions are determined by the breakout shock velocity v{sub 0} and the pre-shock breakout density {rho}{sub 0} and depend weakly on the value of n. Fitting formulae for the peak surface temperature at breakout as a function of v{sub 0} and {rho}{sub 0} are provided, with T{sub peak} approx. 9.44 exp [12.63(v{sub 0}/c){sup 1/2}] eV, and the time dependence of the surface temperature is tabulated. The time integrated emitted spectrum is a robust prediction of the model, determined by T{sub peak} and v{sub 0} alone and insensitive to details of light travel time or slight deviations from spherical symmetry. Adopting commonly assumed progenitor parameters, breakout luminosities of Almost-Equal-To 10{sup 45} erg s{sup -1} and Almost-Equal-To 10{sup 44} erg s{sup -1} in the 0.3-10 keV band are expected for blue supergiant (BSG) and red supergiant (RSG)/He-WR progenitors, respectively (T{sub peak} is well below the band for RSGs, unless their radius is {approx}10{sup 13} cm). >30 detections of SN 1987A-like (BSG) breakouts are expected over the lifetime of ROSAT and XMM-Newton. An absence of such detections would imply either that the typical parameters assumed for BSG progenitors are grossly incorrect or that their envelopes are not hydrostatic. The observed spectrum and duration of XRF 080109/SN 2008D are in tension with a non-relativistic breakout from a stellar surface interpretation.
Quantum diffusion of a relativistic particle in a time-dependent random potential.
Sepehrinia, Reza
2015-04-01
We present a rigorous study of quantum diffusion of a relativistic particle subjected to a time-dependent random potential with δ correlation in time. We find that in the asymptotic time limit the particle wave packet spreads ballistically in contrast with the nonrelativistic case, which in the same situation exhibits superballistic diffusion. The relativistic suppression of wave packet diffusion is discussed in connection with statistical conservation laws that follow from relativistic dynamics. PMID:25974441
Baryons in multicolor chromodynamics
NASA Astrophysics Data System (ADS)
Ioffe, B. L.; Shifman, M. A.
1982-07-01
Spin- {1}/{2} baryons built from massless quarks are considered in the limit of a large number of colors, N → ∞. We obtain a formula expressing the baryon mass mB in terms of the quark condensate <0∣ overlineqq∣0> . As was anticipated, mB ˜ N. We discuss also the behavior of the coupling constants gπNN and gA and some properties of baryonic and mesonic spectra.
NASA Astrophysics Data System (ADS)
Goldstein, Sheldon; Struyve, Ward
2015-01-01
Non-relativistic de Broglie-Bohm theory describes particles moving under the guidance of the wave function. In de Broglie's original formulation, the particle dynamics is given by a first-order differential equation. In Bohm's reformulation, it is given by Newton's law of motion with an extra potential that depends on the wave function—the quantum potential—together with a constraint on the possible velocities. It was recently argued, mainly by numerical simulations, that relaxing this velocity constraint leads to a physically untenable theory. We provide further evidence for this by showing that for various wave functions the particles tend to escape the wave packet. In particular, we show that for a central classical potential and bound energy eigenstates the particle motion is often unbounded. This work seems particularly relevant for ways of simulating wave function evolution based on Bohm's formulation of the de Broglie-Bohm theory. Namely, the simulations may become unstable due to deviations from the velocity constraint.
Decay widths of ground-state and excited {Xi}{sub b} baryons in a nonrelativistic quark model
Limphirat, Ayut; Kobdaj, Chinorat; Suebka, Prasart; Yan, Yupeng
2010-11-15
Decay processes of ground and excited bottom baryons are studied in the {sup 3}P{sub 0} nonrelativistic quark model with all model parameters fixed in the sector of light quarks. Using as an input the recent mass of {Xi}{sub b} and the theoretical masses of {Xi}{sub b}{sup *} and {Xi}{sub b}{sup '}, narrow decay widths are predicted for the ground-state bottom baryons {Xi}{sub b}{sup *} and {Xi}{sub b}{sup '}. The work predicts large decay widths, about 100 MeV for the {rho}-type orbital excitation states of {Xi}{sub b}.
NASA Astrophysics Data System (ADS)
Le Gouët, Jean-Louis; Moiseev, Sergey
2012-06-01
Interaction of quantum radiation with multi-particle ensembles has sparked off intense research efforts during the past decade. Emblematic of this field is the quantum memory scheme, where a quantum state of light is mapped onto an ensemble of atoms and then recovered in its original shape. While opening new access to the basics of light-atom interaction, quantum memory also appears as a key element for information processing applications, such as linear optics quantum computation and long-distance quantum communication via quantum repeaters. Not surprisingly, it is far from trivial to practically recover a stored quantum state of light and, although impressive progress has already been accomplished, researchers are still struggling to reach this ambitious objective. This special issue provides an account of the state-of-the-art in a fast-moving research area that makes physicists, engineers and chemists work together at the forefront of their discipline, involving quantum fields and atoms in different media, magnetic resonance techniques and material science. Various strategies have been considered to store and retrieve quantum light. The explored designs belong to three main—while still overlapping—classes. In architectures derived from photon echo, information is mapped over the spectral components of inhomogeneously broadened absorption bands, such as those encountered in rare earth ion doped crystals and atomic gases in external gradient magnetic field. Protocols based on electromagnetic induced transparency also rely on resonant excitation and are ideally suited to the homogeneous absorption lines offered by laser cooled atomic clouds or ion Coulomb crystals. Finally off-resonance approaches are illustrated by Faraday and Raman processes. Coupling with an optical cavity may enhance the storage process, even for negligibly small atom number. Multiple scattering is also proposed as a way to enlarge the quantum interaction distance of light with matter. The
NASA Astrophysics Data System (ADS)
Weinfurter, Harald; Zeilinger, Anton
Quantum entanglement lies at the heart of the new field of quantum communication and computation. For a long time, entanglement was seen just as one of those fancy features which make quantum mechanics so counterintuitive. But recently, quantum information theory has shown the tremendous importance of quantum correlations for the formulation of new methods of information transfer and for algorithms exploiting the capabilities of quantum computers.This chapter describes the first experimental realizations of quantum communication schemes using entangled photon pairs. We show how to make communication secure against eavesdropping using entanglement-based quantum cryptography, how to increase the information capacity of a quantum channel by quantum dense coding and, finally, how to communicate quantum information itself in the process of quantum teleportation.
Quantum gravitational decoherence of light and matter
NASA Astrophysics Data System (ADS)
Oniga, Teodora; Wang, Charles H.-T.
2016-02-01
Real world quantum systems are open to perpetual influence from the wider environment. Quantum gravitational fluctuations provide a most fundamental source of the environmental influence through their universal interactions with all forms of energy and matter causing decoherence. This may have subtle implications on precision laboratory experiments and astronomical observations and could limit the ultimate capacities for quantum technologies prone to decoherence. To establish the essential physical mechanism of decoherence under weak spacetime fluctuations, we carry out a sequence of analytical steps utilizing the Dirac constraint quantization and gauge invariant influence functional techniques resulting in a general master equation of a compact form that describes an open quantum gravitational system with arbitrary bosonic fields. An initial application of the theory is illustrated by the implied quantum gravitational dissipation of light as well as (non)relativistic massive or massless scalar particles. Related effects could eventually lead to important physical consequences including those on a cosmological scale and for a large number of correlated particles.
NASA Astrophysics Data System (ADS)
Kaur, Gurpreet; Mittal, Raj
2014-11-01
Average M shell fluorescence yield (ϖM) have been calculated from non-relativistic data of McGuire (Phys Rev A 1972;5:1043-47) in the region Z=60-90 and relativistic data of Chen, Crasemann and Mark (Phys Rev A 1980;21:449-53) and (Phys Rev A 1983;27:2989-94) in the region Z=70-90 on M sub-shell fluorescence yield (ωMi, i=1-5) and Coster-Kronig yield (fMij, i=1-4, j=2-5) procured from our earlier work (a computer software code MFCKYLD) using Scofield's data (Lawrence Livermore Laboratory Report UCRL 51326; 1973) on M sub-shell photo-ionization cross-sections. Subsequently, a computer software code AMSFYLD was developed to generate the yield values on computer terminal or in file for both non-relativistic and relativistic data just by entering the atomic number Z of the element through keyboard or file. The values were compared with available theoretical and experimental values in the literature. The agreement between the present data and the other supports the present values.
The impact of QCD and light-cone quantum mechanics on nuclear physics
Brodsky, S.J.; Schlumpf, F.
1994-12-01
We discuss a number of novel applications of Quantum Chromodynamics to nuclear structure and dynamics, such as the reduced amplitude formalism for exclusive nuclear amplitudes. We particularly emphasize the importance of light-cone Hamiltonian and Fock State methods as a tool for describing the wavefunctions of composite relativistic many-body systems and their interactions. We also show that the use of covariant kinematics leads to nontrivial corrections to the standard formulae for the axial, magnetic, and quadrupole moments of nucleons and nuclei.
NASA Astrophysics Data System (ADS)
Georgescu, I. M.; Ashhab, S.; Nori, Franco
2014-01-01
Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry, and cosmology. Quantum simulation could be implemented using quantum computers, but also with simpler, analog devices that would require less control, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar molecules, electrons in semiconductors, superconducting circuits, nuclear spins, and photons have been proposed as quantum simulators. This review outlines the main theoretical and experimental aspects of quantum simulation and emphasizes some of the challenges and promises of this fast-growing field.
Quantum power functional theory for many-body dynamics
Schmidt, Matthias
2015-11-07
We construct a one-body variational theory for the time evolution of nonrelativistic quantum many-body systems. The position- and time-dependent one-body density, particle current, and time derivative of the current act as three variational fields. The generating (power rate) functional is minimized by the true current time derivative. The corresponding Euler-Lagrange equation, together with the continuity equation for the density, forms a closed set of one-body equations of motion. Space- and time-nonlocal one-body forces are generated by the superadiabatic contribution to the functional. The theory applies to many-electron systems.
Quantum power functional theory for many-body dynamics.
Schmidt, Matthias
2015-11-01
We construct a one-body variational theory for the time evolution of nonrelativistic quantum many-body systems. The position- and time-dependent one-body density, particle current, and time derivative of the current act as three variational fields. The generating (power rate) functional is minimized by the true current time derivative. The corresponding Euler-Lagrange equation, together with the continuity equation for the density, forms a closed set of one-body equations of motion. Space- and time-nonlocal one-body forces are generated by the superadiabatic contribution to the functional. The theory applies to many-electron systems.
Murguia, Gabriela; Moreno, Matias; Torres, Manuel
2009-04-20
A well known example in quantum electrodynamics (QED) shows that Coulomb scattering of unpolarized electrons, calculated to lowest order in perturbation theory, yields a results that exactly coincides (in the non-relativistic limit) with the Rutherford formula. We examine an analogous example, the classical and perturbative quantum scattering of an electron by a magnetic field confined in an infinite solenoid of finite radius. The results obtained for the classical and the quantum differential cross sections display marked differences. While this may not be a complete surprise, one should expect to recover the classical expression by applying the classical limit to the quantum result. This turn not to be the case. Surprisingly enough, it is shown that the classical result can not be recuperated even if higher order corrections are included. To recover the classic correspondence of the quantum scattering problem a suitable non-perturbative methodology should be applied.
Quantum correlations which imply causation.
Fitzsimons, Joseph F; Jones, Jonathan A; Vedral, Vlatko
2015-01-01
In ordinary, non-relativistic, quantum physics, time enters only as a parameter and not as an observable: a state of a physical system is specified at a given time and then evolved according to the prescribed dynamics. While the state can, and usually does, extend across all space, it is only defined at one instant of time. Here we ask what would happen if we defined the notion of the quantum density matrix for multiple spatial and temporal measurements. We introduce the concept of a pseudo-density matrix (PDM) which treats space and time indiscriminately. This matrix in general fails to be positive for measurement events which do not occur simultaneously, motivating us to define a measure of causality that discriminates between spatial and temporal correlations. Important properties of this measure, such as monotonicity under local operations, are proved. Two qubit NMR experiments are presented that illustrate how a temporal pseudo-density matrix approaches a genuinely allowed density matrix as the amount of decoherence is increased between two consecutive measurements.
Quantum correlations which imply causation
Fitzsimons, Joseph F.; Jones, Jonathan A.; Vedral, Vlatko
2015-01-01
In ordinary, non-relativistic, quantum physics, time enters only as a parameter and not as an observable: a state of a physical system is specified at a given time and then evolved according to the prescribed dynamics. While the state can, and usually does, extend across all space, it is only defined at one instant of time. Here we ask what would happen if we defined the notion of the quantum density matrix for multiple spatial and temporal measurements. We introduce the concept of a pseudo-density matrix (PDM) which treats space and time indiscriminately. This matrix in general fails to be positive for measurement events which do not occur simultaneously, motivating us to define a measure of causality that discriminates between spatial and temporal correlations. Important properties of this measure, such as monotonicity under local operations, are proved. Two qubit NMR experiments are presented that illustrate how a temporal pseudo-density matrix approaches a genuinely allowed density matrix as the amount of decoherence is increased between two consecutive measurements. PMID:26675807
Dragan, Andrzej; Fuentes, Ivette; Louko, Jorma
2011-04-15
A single quantum system, such as the Unruh-DeWitt detector, can be used to determine absolute acceleration by local measurements on a quantum field. To show this, we consider two kinematically indistinguishable scenarios: an inertial observer, Bob, measuring the field of a uniformly accelerated cavity, and his noninertial twin, Rob, accelerating and making measurements in a stationary cavity. We find that these scenarios can be distinguished in the nonrelativistic regime only by measurements on highly excited massive fields, allowing one to detect the noninertialness of the reference frame.
Manakov, N. L. Krylovetsky, A. A.; Marmo, S. I.
2015-11-15
Compact analytic expressions have been derived by a direct expansion in ħ → 0 for the nonrelativistic amplitude of Coulomb bremsstrahlung radiation (BR), the differential (in frequency and angles of the scattered electron) BR cross section, and the triply differential BR cross section that takes into account the bremsstrahlung photon direction and polarization and the scattered electron direction. They contain the classical limit and a quantum correction of the order of ħ at an arbitrary BR frequency ω. An explicit expression has been found for the quantum correction of the order of ħ to the classical BR spectrum.
Emergence of integer quantum Hall effect from chaos
NASA Astrophysics Data System (ADS)
Tian, Chushun; Chen, Yu; Wang, Jiao
2016-02-01
We present an analytic microscopic theory showing that in a large class of spin-1/2 quasiperiodic quantum kicked rotors, a dynamical analog of the integer quantum Hall effect (IQHE) emerges from an intrinsic chaotic structure. Specifically, the inverse of the Planck's quantum (he) and the rotor's energy growth rate mimic the "filling fraction" and the "longitudinal conductivity" in conventional IQHE, respectively, and a hidden quantum number is found to mimic the "quantized Hall conductivity." We show that for an infinite discrete set of critical values of he, the long-time energy growth rate is universal and of order of unity ("metallic" phase), but otherwise vanishes ("insulating" phase). Moreover, the rotor insulating phases are topological, each of which is characterized by a hidden quantum number. This number exhibits universal behavior for small he, i.e., it jumps by unity whenever he decreases, passing through each critical value. This intriguing phenomenon is not triggered by the likes of Landau band filling, well known to be the mechanism for conventional IQHE, and far beyond the canonical Thouless-Kohmoto-Nightingale-Nijs paradigm for quantum Hall transitions. Instead, this dynamical phenomenon is of strong chaos origin; it does not occur when the dynamics is (partially) regular. More precisely, we find that a topological object, similar to the topological theta angle in quantum chromodynamics, emerges from strongly chaotic motion at microscopic scales, and its renormalization gives the hidden quantum number. Our analytic results are confirmed by numerical simulations. Our findings indicate that rich topological quantum phenomena can emerge from chaos and might point to a new direction of study in the interdisciplinary area straddling chaotic dynamics and condensed matter physics. This work is a substantial extension of a short paper published earlier by two of us [Y. Chen and C. Tian, Phys. Rev. Lett. 113, 216802 (2014), 10.1103/PhysRevLett.113.216802].
NASA Astrophysics Data System (ADS)
Ducharme, R.; da Paz, I. G.
2016-08-01
In two recent papers exact Hermite-Gaussian solutions to relativistic wave equations were obtained for both electromagnetic and particle beams. The solutions for particle beams correspond to those of the Schrödinger equation in the nonrelativistic limit. Here, it will be shown that each beam particle has additional 4-momentum resulting from transverse localization compared to a free particle traveling in the same direction as the beam with the same speed. This will be referred to as the quantum 4-potential term since it will be shown to play an analogous role in relativistic Hamiltonian quantum mechanics as the Bohm potential in the nonrelativistic quantum Hamilton-Jacobi equation. Low-order localization effects include orbital angular momentum, Gouy phase, and beam spreading. Toward a more systematic approach for calculating localization effects at all orders, it will be shown that both the electromagnetic and quantum 4-potentials couple into the canonical 4-momentum of a particle in a similar way. This offers the prospect that traditional methods used to calculate the affect of an electromagnetic field on a particle can now be adapted to take localization effects into account. The prospects for measuring higher order quantum 4-potential related effects experimentally are also discussed alongside some questions to challenge the quantum information and quantum field theorists.
Stapp, H.P.
1988-12-01
Quantum ontologies are conceptions of the constitution of the universe that are compatible with quantum theory. The ontological orientation is contrasted to the pragmatic orientation of science, and reasons are given for considering quantum ontologies both within science, and in broader contexts. The principal quantum ontologies are described and evaluated. Invited paper at conference: Bell's Theorem, Quantum Theory, and Conceptions of the Universe, George Mason University, October 20-21, 1988. 16 refs.
Drell, S.D.
1980-09-15
The concept of asymptotic freedom in quantum chromodynamics (QCD) is reviewed. Analogies are drawn to quantum electrodynamics and non-relativistic quantum mechanics. Asymptotic freedom is seen as the effect of anti-shielding due to the quantums of QCD, the gluons, carrying the color charge. Beginning with the Hamiltonian for the color gauge field plus fixed sources of color charge, the interaction energy between two fixed charges is derived. Both the interaction energy and the running coupling constant are seen to decrease with decreasing distance.
Dowdall, R J; Davies, C T H; Horgan, R R; Monahan, C J; Shigemitsu, J
2013-05-31
We present the first lattice QCD calculation of the decay constants f(B) and f(B(s)) with physical light quark masses. We use configurations generated by the MILC Collaboration including the effect of u, d, s, and c highly improved staggered quarks in the sea at three lattice spacings and with three u/d quark mass values going down to the physical value. We use improved nonrelativistic QCD (NRQCD) for the valence b quarks. Our results are f(B)=0.186(4) GeV, f(B(s))=0.224(4) GeV, f(B(s))/f(B)=1.205(7), and M(B(s))-M(B)=85(2) MeV, superseding earlier results with NRQCD b quarks. We discuss the implications of our results for the standard model rates for B((s))→μ(+)μ(-) and B→τν.
Quantum Computer Games: Quantum Minesweeper
ERIC Educational Resources Information Center
Gordon, Michal; Gordon, Goren
2010-01-01
The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…
Composition in the Quantum World
NASA Astrophysics Data System (ADS)
Hall, Edward Jonathan
This thesis presents a problem for the foundations of quantum mechanics. It arises from the way that theory describes the composition of larger systems in terms of smaller ones, and renders untenable a wide range of interpretations of quantum mechanics. That quantum mechanics is difficult to interpret is old news, given the well-known Measurement Problem. But the problem I raise is quite different, and in important respects more fundamental. In brief: The physical world exhibits mereological structure: physical objects have parts, which in turn have parts, and so on. A natural way to try to represent this structure is by means of a particle theory, according to which the physical world consists entirely enduring physical objects which themselves have no proper parts, but aggregates of which are, or compose, all physical objects. Elementary, non-relativistic quantum mechanics can be cast in this mold--at least, according to the usual expositions of that theory. But herein lies the problem: the standard attempt to give a systematic particle interpretation to elementary quantum mechanics results in nonsense, thanks to the well-established principle of Permutation Invariance, which constrains the quantum -mechanical description of systems containing identical particles. Specifically, it follows from the most minimal principles of a particle interpretation (much weaker than those needed to generate the Measurement Problem), together with Permutation Invariance, that systems identical in composition must have the same physical state. In other words, systems which merely have the same numbers of the same types of particles are therefore, at all times, perfect physical duplicates. This conclusion is absurd: e.g., it is quite plausible that some of those particles which compose my body make up a system identical in composition to some pepperoni pizza. Yet no part of me is a qualitative physical duplicate of any pepperoni pizza. Perhaps "you are what you eat" --but not in
Foundations of a spacetime path formalism for relativistic quantum mechanics
Seidewitz, Ed
2006-11-15
Quantum field theory is the traditional solution to the problems inherent in melding quantum mechanics with special relativity. However, it has also long been known that an alternative first-quantized formulation can be given for relativistic quantum mechanics, based on the parametrized paths of particles in spacetime. Because time is treated similarly to the three space coordinates, rather than as an evolution parameter, such a spacetime approach has proved particularly useful in the study of quantum gravity and cosmology. This paper shows how a spacetime path formalism can be considered to arise naturally from the fundamental principles of the Born probability rule, superposition, and Poincare invariance. The resulting formalism can be seen as a foundation for a number of previous parametrized approaches in the literature, relating, in particular, 'off-shell' theories to traditional on-shell quantum field theory. It reproduces the results of perturbative quantum field theory for free and interacting particles, but provides intriguing possibilities for a natural program for regularization and renormalization. Further, an important consequence of the formalism is that a clear probabilistic interpretation can be maintained throughout, with a natural reduction to nonrelativistic quantum mechanics.
NASA Astrophysics Data System (ADS)
Halliwell, Jonathan J.; Ortiz, Miguel E.
1993-07-01
This paper is concerned with the question of the existence of composition laws in the sum-over-histories approach to relativistic quantum mechanics and quantum cosmology, and its connection with the existence of a canonical formulation. In nonrelativistic quantum mechanics, the propagator is represented by a sum over histories in which the paths move forward in time. The composition law of the propagator then follows from the fact that the paths intersect an intermediate surface of constant time once and only once, and a partition of the paths according to their crossing position may be affected. In relativistic quantum mechanics, by contrast, the propagators (or Green functions) may be represented by sums over histories in which the paths move backward and forward in time. They therefore intersect surfaces of constant time more than once, and the relativistic composition law, involving a normal derivative term, is not readily recovered. The principal technical aim of this paper is to show that the relativistic composition law may, in fact, be derived directly from a sum over histories by partitioning the paths according to their first crossing position of an intermediate surface. We review the various Green functions of the Klein-Gordon equation, and derive their composition laws. We obtain path-integral representations for all Green functions except the causal one. We use the proper time representation, in which the path integral has the form of a nonrelativistic sum over histories but is integrated over time. The question of deriving the composition laws therefore reduces to the question of factoring the propagators of nonrelativistic quantum mechanics across an arbitrary surface in configuration space. This may be achieved using a known result called the path decomposition expansion (PDX). We give a proof of the PDX using a spacetime lattice definition of the Euclidean propagator. We use the PDX to derive the composition laws of relativistic quantum mechanics
Pfeiffer, P.; Egusquiza, I. L.; Di Ventra, M.; Sanz, M.; Solano, E.
2016-01-01
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems. PMID:27381511
Pfeiffer, P; Egusquiza, I L; Di Ventra, M; Sanz, M; Solano, E
2016-01-01
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems. PMID:27381511
Pfeiffer, P; Egusquiza, I L; Di Ventra, M; Sanz, M; Solano, E
2016-07-06
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.
NASA Astrophysics Data System (ADS)
Pfeiffer, P.; Egusquiza, I. L.; di Ventra, M.; Sanz, M.; Solano, E.
2016-07-01
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.
NASA Astrophysics Data System (ADS)
Brzeziński, Tomasz; Fairfax, Simon A.
2012-11-01
Algebras of functions on quantum weighted projective spaces are introduced, and the structure of quantum weighted projective lines or quantum teardrops is described in detail. In particular the presentation of the coordinate algebra of the quantum teardrop in terms of generators and relations and classification of irreducible *-representations are derived. The algebras are then analysed from the point of view of Hopf-Galois theory or the theory of quantum principal bundles. Fredholm modules and associated traces are constructed. C*-algebras of continuous functions on quantum weighted projective lines are described and their K-groups computed.
Alba, David; Crater, Horace W.; Lusanna, Luca
2011-06-15
A new formulation of relativistic quantum mechanics is proposed in the framework of the rest-frame instant form of dynamics, where the world-lines of the particles are parametrized in terms of the Fokker-Pryce center of inertia and of Wigner-covariant relative 3-coordinates inside the instantaneous Wigner 3-spaces, and where there is a decoupled (non-covariant and non-local) canonical relativistic center of mass. This approach: (a) allows us to make a consistent quantization in every inertial frame; (b) leads to a description of both bound and scattering states; (c) offers new insights on the relativistic localization problem; (d) leads to a non-relativistic limit with a Hamilton-Jacobi treatment of the Newton center of mass; (e) clarifies non-local aspects (spatial non-separability) of relativistic entanglement connected with Lorentz signature and not present in its non-relativistic treatment.
Zurek, Wojciech H
2008-01-01
Quantum Darwinism - proliferation, in the environment, of multiple records of selected states of the system (its information-theoretic progeny) - explains how quantum fragility of individual state can lead to classical robustness of their multitude.
Pfeiffer, P.; Egusquiza, I. L.; Di Ventra, M.; Sanz, M.; Solano, E.
2016-07-06
Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantummore » regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. As a result, the proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems.« less
Geometric Aspects of Quantum Hall States
NASA Astrophysics Data System (ADS)
Gromov, Andrey
Explanation of the quantization of the Hall conductance at low temperatures in strong magnetic field is one of the greatest accomplishments of theoretical physics of the end of the 20th century. Since the publication of the Laughlin's charge pumping argument condensed matter theorists have come a long way to topological insulators, classification of noninteracting (and sometimes interacting) topological phases of matter, non-abelian statistics, Majorana zero modes in topological superconductors and topological quantum computation---the framework for "error-free'' quantum computation. While topology was very important in these developments, geometry has largely been neglected. We explore the role of space-time symmetries in topological phases of matter. Such symmetries are responsible for the conservation of energy, momentum and angular momentum. We will show that if these symmetries are maintained (at least on average) then in addition to Hall conductance there are other, in principle, measurable transport coefficients that are quantized and sensitive to topological phase transition. Among these coefficients are non-dissipative viscosity of quantum fluids, known as Hall viscosity; thermal Hall conductance, and a recently discovered coefficient---orbital spin variance. All of these coefficients can be computed as linear responses to variations of geometry of a physical sample. We will show how to compute these coefficients for a variety of abelian and non-abelian quantum Hall states using various analytical tools: from RPA-type perturbation theory to non-abelian Chern-Simons-Witten effective topological quantum field theory. We will explain how non-Riemannian geometry known as Newton-Cartan (NC) geometry arises in the computation of momentum and energy transport in non-relativistic gapped systems. We use this geometry to derive a number of thermodynamic relations and stress the non-relativistic nature of condensed matter systems. NC geometry is also useful in the
Entanglement spectrum and Rényi entropies of nonrelativistic conformal fermions
NASA Astrophysics Data System (ADS)
Porter, William J.; Drut, Joaquín E.
2016-10-01
We characterize nonperturbatively the Rényi entropies of degree n =2 ,3 ,4 , and 5 of three-dimensional, strongly coupled many-fermion systems in the scale-invariant regime of short interaction range and large scattering length, i.e., in the unitary limit. We carry out our calculations using lattice methods devised recently by us. Our results show the effect of strong pairing correlations on the entanglement entropy, which modify the subleading behavior for large subsystem sizes (as characterized by the dimensionless parameter x =kFLA , where kF is the Fermi momentum and LA the linear subsystem size), but leave the leading order unchanged relative to the noninteracting case. Moreover, we find that the onset of the subleading asymptotic regime is at surprisingly small x ≃2 -4 . We provide further insight into the entanglement properties of this system by analyzing the spectrum of the entanglement Hamiltonian of the two-body problem from weak to strong coupling. The low-lying entanglement spectrum displays clear features as the strength of the coupling is varied, such as eigenvalue crossing and merging, a sharp change in the Schmidt gap, and scale invariance at unitarity. Beyond the low-lying component, the spectrum appears as a quasicontinuum distribution, for which we present a statistical characterization; we find, in particular, that the mean shifts to infinity as the coupling is turned off, which indicates that that part of the spectrum represents nonperturbative contributions to the entanglement Hamiltonian. In contrast, the low-lying entanglement spectrum evolves to finite values in the noninteracting limit. The scale invariance of the unitary regime guarantees that our results are universal features intrinsic to three-dimensional quantum mechanics and represent a well-defined prediction for ultracold atom experiments, which were recently shown to have direct access to the entanglement entropy.
NASA Astrophysics Data System (ADS)
Coleman, Piers; Schofield, Andrew J.
2005-01-01
As we mark the centenary of Albert Einstein's seminal contribution to both quantum mechanics and special relativity, we approach another anniversary - that of Einstein's foundation of the quantum theory of solids. But 100 years on, the same experimental measurement that puzzled Einstein and his contemporaries is forcing us to question our understanding of how quantum matter transforms at ultra-low temperatures.
Wake potential with exchange-correlation effects in semiconductor quantum plasmas
Khan, Arroj A.; Jamil, M.; Hussain, A.
2015-09-15
Using the non-relativistic quantum hydrodynamic model, wake potential has been studied in a magnetized semiconductor quantum plasma in the presence of upper hybrid wave which is excited via externally injected electron beam. The quantum effect contains electron exchange and correlation potential, Fermi degenerate pressure, and Bohm potential. It is found that the contribution of quantum mechanical electron exchange and correlation potential significantly modifies the amplitude and the effective length of the oscillatory wake potential. In the electron-hole plasma systems, electron exchange-correlation effects tend to increase the magnitude of the wake potential and are much effective at the distances of the order of Debye-length. The application of the work in context of the semiconductor plasmas have also been analyzed graphically.
NASA Astrophysics Data System (ADS)
Brown, Matthew J.
2014-02-01
The framework of quantum frames can help unravel some of the interpretive difficulties i the foundation of quantum mechanics. In this paper, I begin by tracing the origins of this concept in Bohr's discussion of quantum theory and his theory of complementarity. Engaging with various interpreters and followers of Bohr, I argue that the correct account of quantum frames must be extended beyond literal space-time reference frames to frames defined by relations between a quantum system and the exosystem or external physical frame, of which measurement contexts are a particularly important example. This approach provides superior solutions to key EPR-type measurement and locality paradoxes.
NASA Astrophysics Data System (ADS)
Moulick, Subhayan Roy; Panigrahi, Prasanta K.
2016-06-01
We propose the idea of a quantum cheque scheme, a cryptographic protocol in which any legitimate client of a trusted bank can issue a cheque, that cannot be counterfeited or altered in anyway, and can be verified by a bank or any of its branches. We formally define a quantum cheque and present the first unconditionally secure quantum cheque scheme and show it to be secure against any no-signalling adversary. The proposed quantum cheque scheme can been perceived as the quantum analog of Electronic Data Interchange, as an alternate for current e-Payment Gateways.
NASA Astrophysics Data System (ADS)
Zurek, Wojciech Hubert
2009-03-01
Quantum Darwinism describes the proliferation, in the environment, of multiple records of selected states of a quantum system. It explains how the quantum fragility of a state of a single quantum system can lead to the classical robustness of states in their correlated multitude; shows how effective `wave-packet collapse' arises as a result of the proliferation throughout the environment of imprints of the state of the system; and provides a framework for the derivation of Born's rule, which relates the probabilities of detecting states to their amplitudes. Taken together, these three advances mark considerable progress towards settling the quantum measurement problem.
NASA Astrophysics Data System (ADS)
Bakke, K.; Furtado, C.; Belich, H.
2016-09-01
From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov-Casher geometric quantum phase in the nonrelativistic limit.
NASA Astrophysics Data System (ADS)
Fehr, Serge
2010-05-01
Quantum cryptography makes use of the quantum-mechanical behavior of nature for the design and analysis of cryptographic schemes. Optimally (but not always), quantum cryptography allows for the design of cryptographic schemes whose security is guaranteed solely by the laws of nature. This is in sharp contrast to standard cryptographic schemes, which can be broken in principle, i.e., when given sufficient computing power. From a theory point of view, quantum cryptography offers a beautiful interplay between the mathematics of adversarial behavior and quantum information theory. In this review article, we discuss the traditional application of quantum cryptography, quantum key distribution (QKD), from a modern perspective, and we discuss some recent developments in the context of quantum two-party cooperation (2PC). QKD allows two distant parties to communicate in a provably-secure way in the presence of an outside eavesdropper, whereas 2PC is concerned with protecting information against possibly malicious insiders. We show the basic idea of constructing quantum cryptographic schemes, but we also show some connections to quantum information theory as needed for the rigorous security analyses, and we discuss some of the relevant quantum-information-theoretic results.
NASA Astrophysics Data System (ADS)
Orvil Scully, Marlan; Zubairy, Muhammad Suhail
1997-09-01
Quantum optics has witnessed significant theoretical and experimental developments in recent years. This book provides an in-depth and wide-ranging introduction to the subject, emphasizing throughout the basic principles and their applications. The book begins by developing the basic tools of quantum optics, and goes on to show the application of these tools in a variety of quantum optical systems, including lasing without inversion, squeezed states, and atom optics. The final four chapters discuss quantum optical tests of the foundations of quantum mechanics, and particular aspects of measurement theory. Assuming only a background of standard quantum mechanics and electromagnetic theory, and containing many problems and references, this book will be invaluable to graduate students of quantum optics, as well as to researchers in this field.
Time of arrival in quantum mechanics
Grot, N.; Rovelli, C.; Tate, R.S.
1996-12-01
We study the problem of computing the probability for the time of arrival of a quantum particle at a given spatial position. We consider a solution to this problem based on the spectral decomposition of the particle{close_quote}s (Heisenberg) state into the eigenstates of a suitable operator, which we denote as the {open_quote}{open_quote}time-of-arrival{close_quote}{close_quote} operator. We discuss the general properties of this operator. We construct the operator explicitly in the simple case of a free nonrelativistic particle and compare the probabilities it yields with the ones estimated indirectly in terms of the flux of the Schr{umlt o}dinger current. We derive a well-defined uncertainty relation between time of arrival and energy; this result shows that the well-known arguments against the existence of such a relation can be circumvented. Finally, we define a {open_quote}{open_quote}time representation{close_quote}{close_quote} of the quantum mechanics of a free particle, in which the time of arrival is diagonal. Our results suggest that, contrary to what is commonly assumed, quantum mechanics exhibits a hidden equivalence between independent (time) and dependent (position) variables, analogous to the one revealed by the parametrized formalism in classical mechanics. {copyright} {ital 1996 The American Physical Society.}
Quantum mechanics with coordinate dependent noncommutativity
Kupriyanov, V. G.
2013-11-15
Noncommutative quantum mechanics can be considered as a first step in the construction of quantum field theory on noncommutative spaces of generic form, when the commutator between coordinates is a function of these coordinates. In this paper we discuss the mathematical framework of such a theory. The noncommutativity is treated as an external antisymmetric field satisfying the Jacobi identity. First, we propose a symplectic realization of a given Poisson manifold and construct the Darboux coordinates on the obtained symplectic manifold. Then we define the star product on a Poisson manifold and obtain the expression for the trace functional. The above ingredients are used to formulate a nonrelativistic quantum mechanics on noncommutative spaces of general form. All considered constructions are obtained as a formal series in the parameter of noncommutativity. In particular, the complete algebra of commutation relations between coordinates and conjugated momenta is a deformation of the standard Heisenberg algebra. As examples we consider a free particle and an isotropic harmonic oscillator on the rotational invariant noncommutative space.
An approach to nonstandard quantum mechanics
NASA Astrophysics Data System (ADS)
Raab, A.
2004-12-01
We use nonstandard analysis to formulate quantum mechanics in hyperfinite-dimensional spaces. Self-adjoint operators on hyperfinite-dimensional spaces have complete eigensets, and bound states and continuum states of a Hamiltonian can thus be treated on an equal footing. We show that the formalism extends the standard formulation of quantum mechanics. To this end we develop the Loeb-function calculus in nonstandard hulls. The idea is to perform calculations in a hyperfinite-dimensional space, but to interpret expectation values in the corresponding nonstandard hull. We further apply the framework to nonrelativistic quantum scattering theory. For time-dependent scattering theory, we identify the starting time and the finishing time of a scattering experiment, and we obtain a natural separation of time scales on which the preparation process, the interaction process, and the detection process take place. For time-independent scattering theory, we derive rigorously explicit formulas for the Mo/ller wave operators and the S-matrix.
Greenwald, Jared; Satheeshkumar, V.H.; Wang, Anzhong E-mail: VHSatheeshkumar@baylor.edu
2010-12-01
We study spherically symmetric static spacetimes generally filled with an anisotropic fluid in the nonrelativistic general covariant theory of gravity. In particular, we find that the vacuum solutions are not unique, and can be expressed in terms of the U(1) gauge field A. When solar system tests are considered, severe constraints on A are obtained, which seemingly pick up the Schwarzschild solution uniquely. In contrast to other versions of the Horava-Lifshitz theory, non-singular static stars made of a perfect fluid without heat flow can be constructed, due to the coupling of the fluid with the gauge field. These include the solutions with a constant pressure. We also study the general junction conditions across the surface of a star. In general, the conditions allow the existence of a thin matter shell on the surface. When applying these conditions to the perfect fluid solutions with the vacuum ones as describing their external spacetimes, we find explicitly the matching conditions in terms of the parameters appearing in the solutions. Such matching is possible even without the presence of a thin matter shell.
Riconda, C.; Weber, S.; Tikhonchuk, V. T.; Adam, J.-C.; Heron, A.
2006-08-15
Two-dimensional particle-in-cell simulations of laser-plasma interaction using a plane-wave geometry show strong bursty stimulated Brillouin backscattering, rapid filamentation, and subsequent plasma cavitation. It is shown that the cavitation is not induced by self-focusing. The electromagnetic fields below the plasma frequency that are excited are related to transient soliton-like structures. At the origin of these solitons is a three-wave decay process exciting new modes in the plasma. The cavitation is responsible for a strong local reduction of the reflectivity and goes along with an efficient but transient heating of the electrons. Once heating ceases, transmission starts to increase. Local as well as global average reflectivities attain a very low value due to strong plasma density variations brought about by the cavitation process. On the one hand, the simulations confirm the existence of a new mechanism of cavity and soliton formation in nonrelativistic laser-plasma interaction in two dimensions, which was shown to exist in one-dimensional simulations [S. Weber, C. Riconda, and V. T. Tikhonchuk, Phys. Rev. Lett. 94, 055005 (2005)]. On the other hand, new aspects are introduced inherently related to the additional degree of freedom.
Durmus, Aysen; Yasuk, Fevziye
2007-02-21
The authors investigate solutions of the three dimensional Klein-Gordon and Schrodinger equations in the presence of a new exactly solvable potential of V(r,theta)=-2De(re/r-(1/2)(re2/r2))+b/r2 sin2 theta+a/r2 cos2 theta type, the so-called double ring-shaped Kratzer potential. For a diatomic molecule system in double ring-shaped Kratzer potential, the exact bound state energy eigenvalues and corresponding wave functions have been determined within the framework of the asymptotic iteration method. Bound state eigenfunction solutions used in applications related to molecular spectroscopy are obtained in terms of confluent hypergeometric function and Jacobi polynomial. This new formulation is tested by calculating the energies of rovibrational states of a number of diatomic molecules. Also, the author-prove that in the nonrelativistic limit c-->infinity, where c is the speed of light, solutions of the Klein-Gordon system converge to those of the Schrodinger system.
Salbi, Pegah; Matzner, Christopher D.; Ro, Stephen; Levin, Yuri
2014-07-20
Non-spherical explosions develop non-radial flows as the pattern of shock emergence progresses across the stellar surface. In supernovae, these flows can limit ejecta speeds, stifle shock breakout emission, and cause collisions outside the star. Similar phenomena occur in stellar and planetary collisions, tidal disruption events, accretion-induced collapses, and propagating detonations. We present two-dimensional, nested-grid Athena simulations of non-radial shock emergence in a frame comoving with the breakout pattern, focusing on the adiabatic, non-relativistic limit in a plane stratified envelope. We set boundary conditions using a known self-similar solution and explore the role of box size and resolution on the result. The shock front curves toward the stellar surface, and exhibits a kink from which weak discontinuities originate. Flow around the point of shock emergence is neither perfectly steady nor self-similar. Waves and vortices, which are not predominantly due to grid effects, emanate from this region. The post-shock flow is deflected along the stellar surface and its pressure disturbs the stellar atmosphere upstream of the emerging shock. We use the numerical results and their analytical limits to predict the effects of radiation transfer and gravity, which are not included in our simulations.
Quantum entanglement, quantum communication and the limits of quantum computing
NASA Astrophysics Data System (ADS)
Ambainis, Andris
Quantum entanglement is a term describing the quantum correlations between different parts of a quantum system. Quantum information theory has developed sophisticated techniques to quantify and study quantum entanglement. In this thesis, we show how to apply those techniques to problems in quantum algorithms, complexity theory, communication and cryptography. The main results are: (1) quantum communication protocols that are exponentially more efficient that conventional (classical) communication protocols, (2) unconditionally secure quantum protocols for cryptographic problems, (3) a new "quantum adversary" method for proving lower bounds on quantum algorithms, (4) a study of "one clean qubit computation", a model related to the experimental implementation of quantum computers using NMR (nucleo-magnetic resonance) technology.
NASA Astrophysics Data System (ADS)
Ryabov, V. A.
2015-08-01
Quantum systems in a mechanical embedding, the breathing mode of a small particles, optomechanical system, etc. are far not the full list of examples in which the volume exhibits quantum behavior. Traditional consideration suggests strain in small systems as a result of a collective movement of particles, rather than the dynamics of the volume as an independent variable. The aim of this work is to show that some problem here might be essentially simplified by introducing periodic boundary conditions. At this case, the volume is considered as the independent dynamical variable driven by the internal pressure. For this purpose, the concept of quantum volume based on Schrödinger’s equation in 𝕋3 manifold is proposed. It is used to explore several 1D model systems: An ensemble of free particles under external pressure, quantum manometer and a quantum breathing mode. In particular, the influence of the pressure of free particle on quantum oscillator is determined. It is shown also that correction to the spectrum of the breathing mode due to internal degrees of freedom is determined by the off-diagonal matrix elements of the quantum stress. The new treatment not using the “force” theorem is proposed for the quantum stress tensor. In the general case of flexible quantum 3D dynamics, quantum deformations of different type might be introduced similarly to monopole mode.
Nonparadoxical loss of information in black hole evaporation in a quantum collapse model
NASA Astrophysics Data System (ADS)
Modak, Sujoy K.; Ortíz, Leonardo; Peña, Igor; Sudarsky, Daniel
2015-06-01
We consider a novel approach to address the black hole information paradox. The idea is based on adapting, to the situation at hand, the modified versions of quantum theory involving spontaneous stochastic dynamical collapse of quantum states, which have been considered in attempts to deal with shortcomings of the standard Copenhagen interpretation of quantum mechanics, in particular, the issue known as "the measurement problem." The new basic hypothesis is that the modified quantum behavior is enhanced in the region of high curvature so that the information encoded in the initial quantum state of the matter fields is rapidly erased as the black hole singularity is approached. We show that in this manner the complete evaporation of the black hole via Hawking radiation can be understood as involving no paradox. Calculations are performed using a modified version of quantum theory known as "continuous spontaneous localization" (CSL), which was originally developed in the context of many-particle nonrelativistic quantum mechanics. We use a version of CSL tailored to quantum field theory and applied in the context of the two -dimensional Callan-Giddings-Harvey-Strominger model. Although the role of quantum gravity in this picture is restricted to the resolution of the singularity, related studies suggest that there might be further connections.
NASA Astrophysics Data System (ADS)
de Martini, Francesco; Santamato, Enrico
2016-04-01
The traditional standard theory of quantum mechanics is unable to solve the spin-statistics problem, i.e. to justify the utterly important “Pauli Exclusion Principle” but by the adoption of the complex standard relativistic quantum field theory. In a recent paper [E. Santamato and F. D. De Martini, Found. Phys. 45 (2015) 858] we presented a complete proof of the spin-statistics problem in the nonrelativistic approximation on the basis of the “Conformal Quantum Geometrodynamics” (CQG). In this paper, by the same theory, the proof of the spin-statistics theorem (SST) is extended to the relativistic domain in the scenario of curved spacetime. No relativistic quantum field operators are used in the present proof and the particle exchange properties are drawn from rotational invariance rather than from Lorentz invariance. Our relativistic approach allows to formulate a manifestly step-by-step Weyl gauge invariant theory and to emphasize some fundamental aspects of group theory in the demonstration. As in the nonrelativistic case, we find once more that the “intrinsic helicity” of the elementary particles enters naturally into play. It is therefore this property, not considered in the standard quantum mechanics (SQM), which determines the correct spin-statistics connection observed in Nature.
NASA Astrophysics Data System (ADS)
Levy, Amikam; Diósi, Lajos; Kosloff, Ronnie
2016-05-01
In this work we present the concept of a quantum flywheel coupled to a quantum heat engine. The flywheel stores useful work in its energy levels, while additional power is extracted continuously from the device. Generally, the energy exchange between a quantum engine and a quantized work repository is accompanied by heat, which degrades the charging efficiency. Specifically when the quantum harmonic oscillator acts as a work repository, quantum and thermal fluctuations dominate the dynamics. Quantum monitoring and feedback control are applied to the flywheel in order to reach steady state and regulate its operation. To maximize the charging efficiency one needs a balance between the information gained by measuring the system and the information fed back to the system. The dynamics of the flywheel are described by a stochastic master equation that accounts for the engine, the external driving, the measurement, and the feedback operations.
Coleman, Piers; Schofield, Andrew J
2005-01-20
As we mark the centenary of Albert Einstein's seminal contribution to both quantum mechanics and special relativity, we approach another anniversary--that of Einstein's foundation of the quantum theory of solids. But 100 years on, the same experimental measurement that puzzled Einstein and his contemporaries is forcing us to question our understanding of how quantum matter transforms at ultra-low temperatures. PMID:15662409
NASA Astrophysics Data System (ADS)
Lanzagorta, Marco; Jitrik, Oliverio; Uhlmann, Jeffrey; Venegas, Salvador
2016-05-01
A major scientific thrust from recent years has been to try to harness quantum phenomena to increase the performance of a wide variety of information processing devices. In particular, quantum radar has emerged as an intriguing theoretical concept that could revolutionize electromagnetic standoff sensing. In this paper we will discuss how the techniques developed for quantum radar could also be used towards the design of novel seismographs able to detect small ground vibrations., We use a hypothetical earthquake warning system in order to compare quantum seismography with traditional seismographic techniques.
NASA Astrophysics Data System (ADS)
Tartakovskii, Alexander
2012-07-01
Part I. Nanostructure Design and Structural Properties of Epitaxially Grown Quantum Dots and Nanowires: 1. Growth of III/V semiconductor quantum dots C. Schneider, S. Hofling and A. Forchel; 2. Single semiconductor quantum dots in nanowires: growth, optics, and devices M. E. Reimer, N. Akopian, M. Barkelid, G. Bulgarini, R. Heeres, M. Hocevar, B. J. Witek, E. Bakkers and V. Zwiller; 3. Atomic scale analysis of self-assembled quantum dots by cross-sectional scanning tunneling microscopy and atom probe tomography J. G. Keizer and P. M. Koenraad; Part II. Manipulation of Individual Quantum States in Quantum Dots Using Optical Techniques: 4. Studies of the hole spin in self-assembled quantum dots using optical techniques B. D. Gerardot and R. J. Warburton; 5. Resonance fluorescence from a single quantum dot A. N. Vamivakas, C. Matthiesen, Y. Zhao, C.-Y. Lu and M. Atature; 6. Coherent control of quantum dot excitons using ultra-fast optical techniques A. J. Ramsay and A. M. Fox; 7. Optical probing of holes in quantum dot molecules: structure, symmetry, and spin M. F. Doty and J. I. Climente; Part III. Optical Properties of Quantum Dots in Photonic Cavities and Plasmon-Coupled Dots: 8. Deterministic light-matter coupling using single quantum dots P. Senellart; 9. Quantum dots in photonic crystal cavities A. Faraon, D. Englund, I. Fushman, A. Majumdar and J. Vukovic; 10. Photon statistics in quantum dot micropillar emission M. Asmann and M. Bayer; 11. Nanoplasmonics with colloidal quantum dots V. Temnov and U. Woggon; Part IV. Quantum Dot Nano-Laboratory: Magnetic Ions and Nuclear Spins in a Dot: 12. Dynamics and optical control of an individual Mn spin in a quantum dot L. Besombes, C. Le Gall, H. Boukari and H. Mariette; 13. Optical spectroscopy of InAs/GaAs quantum dots doped with a single Mn atom O. Krebs and A. Lemaitre; 14. Nuclear spin effects in quantum dot optics B. Urbaszek, B. Eble, T. Amand and X. Marie; Part V. Electron Transport in Quantum Dots Fabricated by
Quantum Larmor radiation in a conformally flat universe
Kimura, Rampei; Nakamura, Gen; Yamamoto, Kazuhiro
2011-02-15
We investigate the quantum effect on the Larmor radiation from a moving charge in an expanding universe based on the framework of the scalar quantum electrodynamics. A theoretical formula for the radiation energy is derived at the lowest order of the perturbation theory with respect to the coupling constant of the scalar quantum electrodynamics. We evaluate the radiation energy on the background universe so that the Minkowski spacetime transits to the Milne universe, in which the equation of motion for the mode function of the free complex scalar field can be exactly solved in an analytic way. Then, the result is compared with the WKB approach, in which the equation of motion of the mode function is constructed with the WKB approximation which is valid as long as the Compton wavelength is shorter than the Hubble horizon length. This demonstrates that the quantum effect on the Larmor radiation of the order e{sup 2}({h_bar}/2{pi}) is determined by a nonlocal integration in time depending on the background expansion. We also compare our result with a recent work by Higuchi and Walker [Phys. Rev. D 80, 105019 (2009)], which investigated the quantum correction to the Larmor radiation from a charged particle in a nonrelativistic motion in a homogeneous electric field.
Dissipative quantum computing with open quantum walks
Sinayskiy, Ilya; Petruccione, Francesco
2014-12-04
An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.
Infinite variance in fermion quantum Monte Carlo calculations
NASA Astrophysics Data System (ADS)
Shi, Hao; Zhang, Shiwei
2016-03-01
For important classes of many-fermion problems, quantum Monte Carlo (QMC) methods allow exact calculations of ground-state and finite-temperature properties without the sign problem. The list spans condensed matter, nuclear physics, and high-energy physics, including the half-filled repulsive Hubbard model, the spin-balanced atomic Fermi gas, and lattice quantum chromodynamics calculations at zero density with Wilson Fermions, and is growing rapidly as a number of problems have been discovered recently to be free of the sign problem. In these situations, QMC calculations are relied on to provide definitive answers. Their results are instrumental to our ability to understand and compute properties in fundamental models important to multiple subareas in quantum physics. It is shown, however, that the most commonly employed algorithms in such situations have an infinite variance problem. A diverging variance causes the estimated Monte Carlo statistical error bar to be incorrect, which can render the results of the calculation unreliable or meaningless. We discuss how to identify the infinite variance problem. An approach is then proposed to solve the problem. The solution does not require major modifications to standard algorithms, adding a "bridge link" to the imaginary-time path integral. The general idea is applicable to a variety of situations where the infinite variance problem may be present. Illustrative results are presented for the ground state of the Hubbard model at half-filling.
Modified stochastic variational approach to non-Hermitian quantum systems
NASA Astrophysics Data System (ADS)
Kraft, Daniel; Plessas, Willibald
2016-08-01
The stochastic variational method has proven to be a very efficient and accurate tool to calculate especially bound states of quantum-mechanical few-body systems. It relies on the Rayleigh-Ritz variational principle for minimizing real eigenenergies of Hermitian Hamiltonians. From molecular to atomic, nuclear, and particle physics there is actually a great demand of describing also resonant states to a high degree of reliance. This is especially true with regard to hadron resonances, which have to be treated in a relativistic framework. So far standard methods of dealing with quantum chromodynamics have not yet succeeded in describing hadron resonances in a realistic manner. Resonant states can be handled by non-Hermitian quantum Hamiltonians. These states correspond to poles in the lower half of the unphysical sheet of the complex energy plane and are therefore intimately connected with complex eigenvalues. Consequently the Rayleigh-Ritz variational principle cannot be employed in the usual manner. We have studied alternative selection principles for the choice of test functions to treat resonances along the stochastic variational method. We have found that a stationarity principle for the complex energy eigenvalues provides a viable method for selecting test functions for resonant states in a constructive manner. We discuss several variants thereof and exemplify their practical efficiencies.
Infinite variance in fermion quantum Monte Carlo calculations.
Shi, Hao; Zhang, Shiwei
2016-03-01
For important classes of many-fermion problems, quantum Monte Carlo (QMC) methods allow exact calculations of ground-state and finite-temperature properties without the sign problem. The list spans condensed matter, nuclear physics, and high-energy physics, including the half-filled repulsive Hubbard model, the spin-balanced atomic Fermi gas, and lattice quantum chromodynamics calculations at zero density with Wilson Fermions, and is growing rapidly as a number of problems have been discovered recently to be free of the sign problem. In these situations, QMC calculations are relied on to provide definitive answers. Their results are instrumental to our ability to understand and compute properties in fundamental models important to multiple subareas in quantum physics. It is shown, however, that the most commonly employed algorithms in such situations have an infinite variance problem. A diverging variance causes the estimated Monte Carlo statistical error bar to be incorrect, which can render the results of the calculation unreliable or meaningless. We discuss how to identify the infinite variance problem. An approach is then proposed to solve the problem. The solution does not require major modifications to standard algorithms, adding a "bridge link" to the imaginary-time path integral. The general idea is applicable to a variety of situations where the infinite variance problem may be present. Illustrative results are presented for the ground state of the Hubbard model at half-filling. PMID:27078480
NASA Astrophysics Data System (ADS)
Wieland, Volkmar; Pohl, Martin; Niemiec, Jacek; Rafighi, Iman; Nishikawa, Ken-Ichi
2016-03-01
For parameters that are applicable to the conditions at young supernova remnants, we present results of two-dimensional, three-vector (2D3V) particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at a 45^\\circ angle to the simulation plane to approximate three-dimensional (3D) physics. We developed an improved clean setup that uses the collision of two plasma slabs with different densities and velocities, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations due to shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales produced by the gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but is commensurate with {\\boldsymbol{E}}× {\\boldsymbol{B}} drift. We observe a stable supra-thermal tail in the ion spectra, but no electron acceleration because the amplitude of the Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other two-dimensional (2D) simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but the pre-acceleration efficacy might be reduced with respect to the 2D results once 3D effects are fully accounted for. Other microphysical factors may also play a part in limiting the amplitude of the Buneman waves or preventing the return of electrons to the foot region.
NASA Technical Reports Server (NTRS)
Lee, H.; Kok, P.; Dowling, J. P.
2002-01-01
This paper addresses the formal equivalence between the Mach-Zehnder interferometer, the Ramsey spectroscope, and a specific quantum logical gate. Based on this equivalence we introduce the quantum Rosetta Stone, and we describe a projective measurement scheme for generating the desired correlations between the interferometric input states in order to achieve Heisenberg-limited sensitivity.
Trevors, J T; Masson, L
2011-01-01
During his famous 1943 lecture series at Trinity College Dublin, the reknown physicist Erwin Schrodinger discussed the failure and challenges of interpreting life by classical physics alone and that a new approach, rooted in Quantum principles, must be involved. Quantum events are simply a level of organization below the molecular level. This includes the atomic and subatomic makeup of matter in microbial metabolism and structures, as well as the organic, genetic information code of DNA and RNA. Quantum events at this time do not elucidate, for example, how specific genetic instructions were first encoded in an organic genetic code in microbial cells capable of growth and division, and its subsequent evolution over 3.6 to 4 billion years. However, due to recent technological advances, biologists and physicists are starting to demonstrate linkages between various quantum principles like quantum tunneling, entanglement and coherence in biological processes illustrating that nature has exerted some level quantum control to optimize various processes in living organisms. In this article we explore the role of quantum events in microbial processes and endeavor to show that after nearly 67 years, Schrödinger was prophetic and visionary in his view of quantum theory and its connection with some of the fundamental mechanisms of life. PMID:21368338
NASA Astrophysics Data System (ADS)
Coecke, Bob
2010-01-01
Why did it take us 50 years since the birth of the quantum mechanical formalism to discover that unknown quantum states cannot be cloned? Yet, the proof of the 'no-cloning theorem' is easy, and its consequences and potential for applications are immense. Similarly, why did it take us 60 years to discover the conceptually intriguing and easily derivable physical phenomenon of 'quantum teleportation'? We claim that the quantum mechanical formalism doesn't support our intuition, nor does it elucidate the key concepts that govern the behaviour of the entities that are subject to the laws of quantum physics. The arrays of complex numbers are kin to the arrays of 0s and 1s of the early days of computer programming practice. Using a technical term from computer science, the quantum mechanical formalism is 'low-level'. In this review we present steps towards a diagrammatic 'high-level' alternative for the Hilbert space formalism, one which appeals to our intuition. The diagrammatic language as it currently stands allows for intuitive reasoning about interacting quantum systems, and trivialises many otherwise involved and tedious computations. It clearly exposes limitations such as the no-cloning theorem, and phenomena such as quantum teleportation. As a logic, it supports 'automation': it enables a (classical) computer to reason about interacting quantum systems, prove theorems, and design protocols. It allows for a wider variety of underlying theories, and can be easily modified, having the potential to provide the required step-stone towards a deeper conceptual understanding of quantum theory, as well as its unification with other physical theories. Specific applications discussed here are purely diagrammatic proofs of several quantum computational schemes, as well as an analysis of the structural origin of quantum non-locality. The underlying mathematical foundation of this high-level diagrammatic formalism relies on so-called monoidal categories, a product of a fairly
NASA Astrophysics Data System (ADS)
Reynolds, Helen
2000-03-01
ability keeping track of the equations and their meaning. However, the text continues to be accessible and moves swiftly from `quantum classics' such as the harmonic oscillator to electrical conductivity and the collapse of stars. Reassuringly, Treiman takes time out to ask `What's going on?' where he considers the question of how probabilities get converted into `facts' when things are measured. His own fascination with the subject comes through as he considers the different interpretations of quantum mechanics. The chapter on `building blocks' starts in 1932 when ` ... it could seem that all the basic building blocks of the whole world were at last in hand'. Swiftly and succinctly it moves through to the standard model, acknowledging that a closer look would ` ... quickly carry us far afield into highly technical thickets'. The final chapter tackles the more difficult subject of quantum field theory. This is a very swift journey through quantum electrodynamics and quantum chromodynamics. It is the final summary that stands out, however. The author reminds us what to marvel about: the miracles of quantum theory that are ` ... outrageous to common sense and intuition'. This is a useful book for any science department. It will be of particular use to those of us who studied the subject some time ago and who need to refresh their memories, for example teachers of A-level physics. The asides about `what is going on' and the history that is included make it a `book' rather than a `textbook'. First-year undergraduates, or just possibly motivated and mathematically able A-level students, would also benefit. Beware, however. The mathematics is not trivial and you would arguably need to have met it before in order to cope. Although the book occasionally relapses into textbook style you are left with a sense of the wonder of the subject and an appreciation of the beauty of the mathematics that underpins it.
NASA Astrophysics Data System (ADS)
Haas, Fernando; Mahmood, Shahzad
2016-09-01
Nonlinear ion-acoustic waves are analyzed in a nonrelativistic magnetized quantum plasma with arbitrary degeneracy of electrons. Quantum statistics is taken into account by means of the equation of state for ideal fermions at arbitrary temperature. Quantum diffraction is described by a modified Bohm potential consistent with finite-temperature quantum kinetic theory in the long-wavelength limit. The dispersion relation of the obliquely propagating electrostatic waves in magnetized quantum plasma with arbitrary degeneracy of electrons is obtained. Using the reductive perturbation method, the corresponding Zakharov-Kuznetsov equation is derived, describing obliquely propagating two-dimensional ion-acoustic solitons in a magnetized quantum plasma with degenerate electrons having an arbitrary electron temperature. It is found that in the dilute plasma case only electrostatic potential hump structures are possible, while in dense quantum plasma, in principle, both hump and dip soliton structures are obtainable, depending on the electron plasma density and its temperature. The results are validated by comparison with the quantum hydrodynamic model including electron inertia and magnetization effects. Suitable physical parameters for observations are identified.
An efficient matrix product operator representation of the quantum chemical Hamiltonian.
Keller, Sebastian; Dolfi, Michele; Troyer, Matthias; Reiher, Markus
2015-12-28
We describe how to efficiently construct the quantum chemical Hamiltonian operator in matrix product form. We present its implementation as a density matrix renormalization group (DMRG) algorithm for quantum chemical applications. Existing implementations of DMRG for quantum chemistry are based on the traditional formulation of the method, which was developed from the point of view of Hilbert space decimation and attained higher performance compared to straightforward implementations of matrix product based DMRG. The latter variationally optimizes a class of ansatz states known as matrix product states, where operators are correspondingly represented as matrix product operators (MPOs). The MPO construction scheme presented here eliminates the previous performance disadvantages while retaining the additional flexibility provided by a matrix product approach, for example, the specification of expectation values becomes an input parameter. In this way, MPOs for different symmetries - abelian and non-abelian - and different relativistic and non-relativistic models may be solved by an otherwise unmodified program.
Is there a "most perfect fluid" consistent with quantum field theory?
Cohen, Thomas D
2007-07-13
It was recently conjectured that the ratio of the shear viscosity to entropy density eta/s for any fluid always exceeds [formula: see text]. A theoretical counterexample to this bound can be constructed from a nonrelativistic gas by increasing the number of species in the fluid while keeping the dynamics essentially independent of the species type. The question of whether the underlying structure of relativistic quantum field theory generically inhibits the realization of such a system and thereby preserves the possibility of a universal bound is considered here. Using rather conservative assumptions, it is shown here that a metastable gas of heavy mesons in a particular controlled regime of QCD provides a realization of the counterexample and is consistent with a well-defined underlying relativistic quantum field theory. Thus, quantum field theory appears to impose no lower bound on eta/s, at least for metastable fluids.
An efficient matrix product operator representation of the quantum chemical Hamiltonian
Keller, Sebastian Reiher, Markus; Dolfi, Michele Troyer, Matthias
2015-12-28
We describe how to efficiently construct the quantum chemical Hamiltonian operator in matrix product form. We present its implementation as a density matrix renormalization group (DMRG) algorithm for quantum chemical applications. Existing implementations of DMRG for quantum chemistry are based on the traditional formulation of the method, which was developed from the point of view of Hilbert space decimation and attained higher performance compared to straightforward implementations of matrix product based DMRG. The latter variationally optimizes a class of ansatz states known as matrix product states, where operators are correspondingly represented as matrix product operators (MPOs). The MPO construction scheme presented here eliminates the previous performance disadvantages while retaining the additional flexibility provided by a matrix product approach, for example, the specification of expectation values becomes an input parameter. In this way, MPOs for different symmetries — abelian and non-abelian — and different relativistic and non-relativistic models may be solved by an otherwise unmodified program.
Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas
Hussain, Azhar; Stefan, Martin; Brodin, Gert
2014-03-15
We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given.
Dirac Equation and Quantum Relativistic Effects in a Single Trapped Ion
Lamata, L.; Leon, J.; Schaetz, T.; Solano, E.
2007-06-22
We present a method of simulating the Dirac equation in 3+1 dimensions for a free spin-1/2 particle in a single trapped ion. The Dirac bispinor is represented by four ionic internal states, and position and momentum of the Dirac particle are associated with the respective ionic variables. We show also how to simulate the simplified 1+1 case, requiring the manipulation of only two internal levels and one motional degree of freedom. Moreover, we study relevant quantum-relativistic effects, like the Zitterbewegung and Klein's paradox, the transition from massless to massive fermions, and the relativistic and nonrelativistic limits, via the tuning of controllable experimental parameters.
Topological quantum scattering under the influence of a nontrivial boundary condition
NASA Astrophysics Data System (ADS)
Mota, Herondy
2016-04-01
We consider the quantum scattering problem of a relativistic particle in (2 + 1)-dimensional cosmic string spacetime under the influence of a nontrivial boundary condition imposed on the solution of the Klein-Gordon equation. The solution is then shifted as consequence of the nontrivial boundary condition and the role of the phase shift is to produce an Aharonov-Bohm-like effect. We examine the connection between this phase shift and the electromagnetic and gravitational analogous of the Aharonov-Bohm effect and compare the present results with previous ones obtained in the literature, also considering non-relativistic cases.
NASA Astrophysics Data System (ADS)
Casati, Giulio; Chirikov, Boris
2006-11-01
Preface; Acknowledgments; Introduction: 1. The legacy of chaos in quantum mechanics G. Casati and B. V. Chirikov; Part I. Classical Chaos and Quantum Localization: 2. Stochastic behaviour of a quantum pendulum under a periodic perturbation G. Casati, B. V. Chirikov, F. M. Izrailev and J. Ford; 3. Quantum dynamics of a nonintegrable system D. R. Grempel, R. E. Prange and S. E. Fishman; 4. Excitation of molecular rotation by periodic microwave pulses. A testing ground for Anderson localization R. Blümel, S. Fishman and U. Smilansky; 5. Localization of diffusive excitation in multi-level systems D. K. Shepelyansky; 6. Classical and quantum chaos for a kicked top F. Haake, M. Kus and R. Scharf; 7. Self-similarity in quantum dynamics L. E. Reichl and L. Haoming; 8. Time irreversibility of classically chaotic quantum dynamics K. Ikeda; 9. Effect of noise on time-dependent quantum chaos E. Ott, T. M. Antonsen Jr and J. D. Hanson; 10. Dynamical localization, dissipation and noise R. F. Graham; 11. Maximum entropy models and quantum transmission in disordered systems J.-L. Pichard and M. Sanquer; 12. Solid state 'atoms' in intense oscillating fields M. S. Sherwin; Part II. Atoms in Strong Fields: 13. Localization of classically chaotic diffusion for hydrogen atoms in microwave fields J. E. Bayfield, G. Casati, I. Guarneri and D. W. Sokol; 14. Inhibition of quantum transport due to 'scars' of unstable periodic orbits R. V. Jensen, M. M. Sanders, M. Saraceno and B. Sundaram; 15. Rubidium Rydberg atoms in strong fields G. Benson, G. Raithel and H. Walther; 16. Diamagnetic Rydberg atom: confrontation of calculated and observed spectra C.-H. Iu, G. R. Welch, M. M. Kash, D. Kleppner, D. Delande and J. C. Gay; 17. Semiclassical approximation for the quantum states of a hydrogen atom in a magnetic field near the ionization limit M. Y. Kuchiev and O. P. Sushkov; 18. The semiclassical helium atom D. Wintgen, K. Richter and G. Tanner; 19. Stretched helium: a model for quantum chaos
NASA Astrophysics Data System (ADS)
Casati, Giulio; Chirikov, Boris
1995-04-01
Preface; Acknowledgments; Introduction: 1. The legacy of chaos in quantum mechanics G. Casati and B. V. Chirikov; Part I. Classical Chaos and Quantum Localization: 2. Stochastic behaviour of a quantum pendulum under a periodic perturbation G. Casati, B. V. Chirikov, F. M. Izrailev and J. Ford; 3. Quantum dynamics of a nonintegrable system D. R. Grempel, R. E. Prange and S. E. Fishman; 4. Excitation of molecular rotation by periodic microwave pulses. A testing ground for Anderson localization R. Blümel, S. Fishman and U. Smilansky; 5. Localization of diffusive excitation in multi-level systems D. K. Shepelyansky; 6. Classical and quantum chaos for a kicked top F. Haake, M. Kus and R. Scharf; 7. Self-similarity in quantum dynamics L. E. Reichl and L. Haoming; 8. Time irreversibility of classically chaotic quantum dynamics K. Ikeda; 9. Effect of noise on time-dependent quantum chaos E. Ott, T. M. Antonsen Jr and J. D. Hanson; 10. Dynamical localization, dissipation and noise R. F. Graham; 11. Maximum entropy models and quantum transmission in disordered systems J.-L. Pichard and M. Sanquer; 12. Solid state 'atoms' in intense oscillating fields M. S. Sherwin; Part II. Atoms in Strong Fields: 13. Localization of classically chaotic diffusion for hydrogen atoms in microwave fields J. E. Bayfield, G. Casati, I. Guarneri and D. W. Sokol; 14. Inhibition of quantum transport due to 'scars' of unstable periodic orbits R. V. Jensen, M. M. Sanders, M. Saraceno and B. Sundaram; 15. Rubidium Rydberg atoms in strong fields G. Benson, G. Raithel and H. Walther; 16. Diamagnetic Rydberg atom: confrontation of calculated and observed spectra C.-H. Iu, G. R. Welch, M. M. Kash, D. Kleppner, D. Delande and J. C. Gay; 17. Semiclassical approximation for the quantum states of a hydrogen atom in a magnetic field near the ionization limit M. Y. Kuchiev and O. P. Sushkov; 18. The semiclassical helium atom D. Wintgen, K. Richter and G. Tanner; 19. Stretched helium: a model for quantum chaos
Quantum strategies of quantum measurements
NASA Astrophysics Data System (ADS)
Li, Chuan-Feng; Zhang, Yong-Sheng; Huang, Yun-Feng; Guo, Guang-Can
2001-03-01
In the classical Monty Hall problem, one player can always win with probability 2/3. We generalize the problem to the quantum domain and show that a fair two-party zero-sum game can be carried out if the other player is permitted to adopt quantum measurement strategy.
Electromagnetic fields on a quantum scale. I.
Grimes, Dale M; Grimes, Craig A
2002-10-01
This is the first in a series of two articles, the second of which provides an exact electro-magnetic field description of photon emission, absorption, and radiation pattern. Photon energy exchanges are analyzed and shown to be the triggered, regenerative response of a non-local eigenstate electron. This first article presents a model-based, hidden variable analysis of quantum theory that provides the statistical nature of wave functions. The analysis uses the equations of classical electro-magnetism and conservation of energy while modeling an eigenstate electron as a nonlocal entity. Essential to the analysis are physical properties that were discovered and analyzed only after the historical interpretation of quantum mechanics was established: electron non-locality and the standing electro-magnetic energy that accompanies and encompasses an active, electrically small volume. The standing energy produces a driving radiation reaction force that, under certain circumstances, is many orders of magnitude larger than currently accepted values. These properties provide a sufficient basis for the Schrödinger equation as a descriptor of non-relativistic eigenstate electrons in or near equilibrium. The uncertainty principle follows, as does the exclusion principle. The analysis leads to atomic stability and causality in the sense that the status of physical phenomena at any instant specifies the status an instant later.
RADIO AND X-RAY OBSERVATIONS OF THE TYPE Ic SN 2007gr REVEAL AN ORDINARY, NON-RELATIVISTIC EXPLOSION
Soderberg, A. M.; Brunthaler, A.; Nakar, E.; Chevalier, R. A.; Bietenholz, M. F.
2010-12-10
We present extensive radio and X-ray observations of the nearby Type Ic SN 2007gr in NGC 1058 obtained with the Very Large Array (VLA) and the Chandra X-ray Observatory and spanning 5 to 150 days after explosion. Through our detailed modeling of these data, we estimate the properties of the blast wave and the circumstellar environment. We find evidence for a freely expanding and non-relativistic explosion with an average blast wave velocity, v-bar {approx}0.2c, and a total internal energy for the radio emitting material of E {approx} 2 x 10{sup 46} erg assuming equipartition of energy between electrons and magnetic fields ({epsilon}{sub e} = {epsilon}{sub B} = 0.1). The temporal and spectral evolution of the radio emission points to a stellar wind-blown environment shaped by a steady progenitor mass loss rate of M-dot {approx}6x10{sup -7} M{sub sun} yr{sup -1} (wind velocity, v{sub w} = 10{sup 3} km s{sup -1}). These parameters are fully consistent with those inferred for other SNe Ibc and are in line with the expectations for an ordinary, homologous SN explosion. Our results are at odds with those of Paragi et al. who recently reported evidence for a relativistic blast wave in SN 2007gr based on their claim that the radio emission was resolved away in a low signal-to-noise Very Long Baseline Interferometry (VLBI) observation. Here we show that the exotic physical scenarios required to explain the claimed relativistic velocity-extreme departures from equipartition and/or a highly collimated outflow-are excluded by our detailed VLA radio observations. Moreover, we present an independent analysis of the VLBI data and propose that a modest loss of phase coherence provides a more natural explanation for the apparent flux density loss which is evident on both short and long baselines. We conclude that SN 2007gr is an ordinary Type Ibc supernova.
Entropic corrected Newton's law of gravitation and the loop quantum black hole gravitational atom
NASA Astrophysics Data System (ADS)
Aragão, R. G. L.; Silva, C. A. S.
2016-07-01
One proposal by Verlinde is that gravity is not a fundamental, but an entropic force (Verlinde in JHEP 1104:029, 2011. arXiv:hep-th/1001.0785). Based on this new interpretation of the gravity, Verlinde has provide us with a way to derive the Newton's law of gravitation from the Bekenstein-Hawking entropy-area formula. On the other hand, since it has been demonstrated that this formula is susceptible to quantum gravity corrections, one may hope that such corrections could be inherited by Newton's law. In this sense, the entropic interpretation of Newton's law could be a prolific way in order to get verifiable or falsifiable quantum corrections to ordinary gravity in an observationally accessible regimes. On the other hand, loop quantum gravity is a theory that provide a scheme to approach the quantum properties of spacetime. From this theory, emerges a quantum corrected semiclassical black hole solution called loop quantum black hole or self-dual black hole. Among the interesting features of loop quantum black holes, is the fact that they give rise to a modified entropy-area relation where quantum gravity corrections are present. In this work, we obtain a quantum corrected Newton's law from the entropy-area relation given by loop quantum black holes by using the nonrelativistic Verlinde's approach. Moreover, in order to relate our results with the recent experimental activity, we consider the quantum mechanical properties of a huge gravitational atom consisting in a light neutral elementary particle in the presence of a loop quantum black hole.
ERIC Educational Resources Information Center
Peterson, Ivars
1989-01-01
An analogy from the game of baseball can be used to examine the philosophy involved in statistics surrounding quantum mechanical events. The "Strong Baseball Principle" is proposed and discussed. (CW)
A wave equation interpolating between classical and quantum mechanics
NASA Astrophysics Data System (ADS)
Schleich, W. P.; Greenberger, D. M.; Kobe, D. H.; Scully, M. O.
2015-10-01
We derive a ‘master’ wave equation for a family of complex-valued waves {{Φ }}\\equiv R{exp}[{{{i}}S}({cl)}/{{\\hbar }}] whose phase dynamics is dictated by the Hamilton-Jacobi equation for the classical action {S}({cl)}. For a special choice of the dynamics of the amplitude R which eliminates all remnants of classical mechanics associated with {S}({cl)} our wave equation reduces to the Schrödinger equation. In this case the amplitude satisfies a Schrödinger equation analogous to that of a charged particle in an electromagnetic field where the roles of the scalar and the vector potentials are played by the classical energy and the momentum, respectively. In general this amplitude is complex and thereby creates in addition to the classical phase {S}({cl)}/{{\\hbar }} a quantum phase. Classical statistical mechanics, as described by a classical matter wave, follows from our wave equation when we choose the dynamics of the amplitude such that it remains real for all times. Our analysis shows that classical and quantum matter waves are distinguished by two different choices of the dynamics of their amplitudes rather than two values of Planck’s constant. We dedicate this paper to the memory of Richard Lewis Arnowitt—a pioneer of many-body theory, a path finder at the interface of gravity and quantum mechanics, and a true leader in non-relativistic and relativistic quantum field theory.
NASA Astrophysics Data System (ADS)
Stapp, Henry P.
2012-05-01
Robert Griffiths has recently addressed, within the framework of a `consistent quantum theory' that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues that the putative proofs of this property that involve hidden variables include in their premises some essentially classical-physics-type assumptions that are not entailed by the precepts of quantum mechanics. Thus whatever is proved is not a feature of quantum mechanics, but is a property of a theory that tries to combine quantum theory with quasi-classical features that go beyond what is entailed by quantum theory itself. One cannot logically prove properties of a system by establishing, instead, properties of a system modified by adding properties alien to the original system. Hence Griffiths' rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his `consistent quantum theory' shows that the cited proof is valid within that restrictive version of quantum theory. An added section responds to Griffiths' reply, which cites general possibilities of ambiguities that might make what is to be proved ill-defined, and hence render the pertinent `consistent framework' ill defined. But the vagaries that he cites do not upset the proof in question, which, both by its physical formulation and by explicit identification, specify the framework to be used. Griffiths confirms the validity of the proof insofar as that pertinent framework is used. The section also shows
Quantum correlations and distinguishability of quantum states
Spehner, Dominique
2014-07-15
A survey of various concepts in quantum information is given, with a main emphasis on the distinguishability of quantum states and quantum correlations. Covered topics include generalized and least square measurements, state discrimination, quantum relative entropies, the Bures distance on the set of quantum states, the quantum Fisher information, the quantum Chernoff bound, bipartite entanglement, the quantum discord, and geometrical measures of quantum correlations. The article is intended both for physicists interested not only by collections of results but also by the mathematical methods justifying them, and for mathematicians looking for an up-to-date introductory course on these subjects, which are mainly developed in the physics literature.
Bubin, Sergiy; Komasa, Jacek; Stanke, Monika; Adamowicz, Ludwik
2010-03-21
We present very accurate quantum mechanical calculations of the three lowest S-states [1s(2)2s(2)((1)S(0)), 1s(2)2p(2)((1)S(0)), and 1s(2)2s3s((1)S(0))] of the two stable isotopes of the boron ion, (10)B(+) and (11)B(+). At the nonrelativistic level the calculations have been performed with the Hamiltonian that explicitly includes the finite mass of the nucleus as it was obtained by a rigorous separation of the center-of-mass motion from the laboratory frame Hamiltonian. The spatial part of the nonrelativistic wave function for each state was expanded in terms of 10,000 all-electron explicitly correlated Gaussian functions. The nonlinear parameters of the Gaussians were variationally optimized using a procedure involving the analytical energy gradient determined with respect to the nonlinear parameters. The nonrelativistic wave functions of the three states were subsequently used to calculate the leading alpha(2) relativistic corrections (alpha is the fine structure constant; alpha=1/c, where c is the speed of light) and the alpha(3) quantum electrodynamics (QED) correction. We also estimated the alpha(4) QED correction by calculating its dominant component. A comparison of the experimental transition frequencies with the frequencies obtained based on the energies calculated in this work shows an excellent agreement. The discrepancy is smaller than 0.4 cm(-1).
NASA Astrophysics Data System (ADS)
Bubin, Sergiy; Komasa, Jacek; Stanke, Monika; Adamowicz, Ludwik
2010-03-01
We present very accurate quantum mechanical calculations of the three lowest S-states [1s22s2(S10), 1s22p2(S10), and 1s22s3s(S10)] of the two stable isotopes of the boron ion, B10+ and B11+. At the nonrelativistic level the calculations have been performed with the Hamiltonian that explicitly includes the finite mass of the nucleus as it was obtained by a rigorous separation of the center-of-mass motion from the laboratory frame Hamiltonian. The spatial part of the nonrelativistic wave function for each state was expanded in terms of 10 000 all-electron explicitly correlated Gaussian functions. The nonlinear parameters of the Gaussians were variationally optimized using a procedure involving the analytical energy gradient determined with respect to the nonlinear parameters. The nonrelativistic wave functions of the three states were subsequently used to calculate the leading α2 relativistic corrections (α is the fine structure constant; α =1/c, where c is the speed of light) and the α3 quantum electrodynamics (QED) correction. We also estimated the α4 QED correction by calculating its dominant component. A comparison of the experimental transition frequencies with the frequencies obtained based on the energies calculated in this work shows an excellent agreement. The discrepancy is smaller than 0.4 cm-1.
NASA Astrophysics Data System (ADS)
Mandl, F.
1992-07-01
The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scientists R. J. Barlow and A. R. Barnett Quantum Mechanics aims to teach those parts of the subject which every physicist should know. The object is to display the inherent structure of quantum mechanics, concentrating on general principles and on methods of wide applicability without taking them to their full generality. This book will equip students to follow quantum-mechanical arguments in books and scientific papers, and to cope with simple cases. To bring the subject to life, the theory is applied to the all-important field of atomic physics. No prior knowledge of quantum mechanics is assumed. However, it would help most readers to have met some elementary wave mechanics before. Primarily written for students, it should also be of interest to experimental research workers who require a good grasp of quantum mechanics without the full formalism needed by the professional theorist. Quantum Mechanics features: A flow diagram allowing topics to be studied in different orders or omitted altogether. Optional "starred" and highlighted sections containing more advanced and specialized material for the more ambitious reader. Sets of problems at the end of each chapter to help student understanding. Hints and solutions to the problems are given at the end of the book.
Introduction to Quantum Simulation
NASA Technical Reports Server (NTRS)
Williams, Colin P.
2005-01-01
This viewgraph presentation addresses the problem of efficiently simulating the evolution of a quantum system. The contents include: 1) Quantum Simulation; 2) Extracting Answers from Quantum Simulations; 3) Quantum Fourier Transform; 4) Eigenvalue Estimation; 5) Fermionic Simulations.
Quantum Physics for Beginners.
ERIC Educational Resources Information Center
Strand, J.
1981-01-01
Suggests a new approach for teaching secondary school quantum physics. Reviews traditional approaches and presents some characteristics of the three-part "Quantum Physics for Beginners" project, including: quantum physics, quantum mechanics, and a short historical survey. (SK)
Dynamical gauge effects in an open quantum network
NASA Astrophysics Data System (ADS)
Zhao, Jianshi; Price, Craig; Liu, Qi; Gemelke, Nathan
2016-05-01
We describe new experimental techniques for simulation of high-energy field theories based on an analogy between open thermodynamic systems and effective dynamical gauge-fields following SU(2) × U(1) Yang-Mills models. By coupling near-resonant laser-modes to atoms moving in a disordered optical environment, we create an open system which exhibits a non-equilibrium phase transition between two steady-state behaviors, exhibiting scale-invariant behavior near the transition. By measuring transport of atoms through the disordered network, we observe two distinct scaling behaviors, corresponding to the classical and quantum limits for the dynamical gauge field. This behavior is loosely analogous to dynamical gauge effects in quantum chromodynamics, and can mapped onto generalized open problems in theoretical understanding of quantized non-Abelian gauge theories. Additional, the scaling behavior can be understood from the geometric structure of the gauge potential and linked to the measure of information in the local disordered potential, reflecting an underlying holographic principle. We acknowledge support from NSF Award No.1068570, and the Charles E. Kaufman Foundation.
NASA Astrophysics Data System (ADS)
Turkington, M. D.; Ballance, C. P.; Hibbert, A.; Ramsbottom, C. A.
2016-08-01
In this work we explore the validity of employing a modified version of the nonrelativistic structure code civ3 for heavy, highly charged systems, using Na-like tungsten as a simple benchmark. Consequently, we present radiative and subsequent collisional atomic data compared with corresponding results from a fully relativistic structure and collisional model. Our motivation for this line of study is to benchmark civ3 against the relativistic grasp0 structure code. This is an important study as civ3 wave functions in nonrelativistic R -matrix calculations are computationally less expensive than their Dirac counterparts. There are very few existing data for the W LXIV ion in the literature with which we can compare except for an incomplete set of energy levels available from the NIST database. The overall accuracy of the present results is thus determined by the comparison between the civ3 and grasp0 structure codes alongside collisional atomic data computed by the R -matrix Breit-Pauli and Dirac codes. It is found that the electron-impact collision strengths and effective collision strengths computed by these differing methods are in good general agreement for the majority of the transitions considered, across a broad range of electron temperatures.
NASA Astrophysics Data System (ADS)
Le Bellac, Michel
2006-03-01
Quantum physics allows us to understand the nature of the physical phenomena which govern the behavior of solids, semi-conductors, lasers, atoms, nuclei, subnuclear particles and light. In Quantum Physics, Le Bellac provides a thoroughly modern approach to this fundamental theory. Throughout the book, Le Bellac teaches the fundamentals of quantum physics using an original approach which relies primarily on an algebraic treatment and on the systematic use of symmetry principles. In addition to the standard topics such as one-dimensional potentials, angular momentum and scattering theory, the reader is introduced to more recent developments at an early stage. These include a detailed account of entangled states and their applications, the optical Bloch equations, the theory of laser cooling and of magneto-optical traps, vacuum Rabi oscillations, and an introduction to open quantum systems. This is a textbook for a modern course on quantum physics, written for advanced undergraduate and graduate students. Completely original and contemporary approach, using algebra and symmetry principles Introduces recent developments at an early stage, including many topics that cannot be found in standard textbooks. Contains 130 physically relevant exercises
NASA Astrophysics Data System (ADS)
Ruggenthaler, Michael; Flick, Johannes; Pellegrini, Camilla; Appel, Heiko; Tokatly, Ilya V.; Rubio, Angel
2014-07-01
In this work, we give a comprehensive derivation of an exact and numerically feasible method to perform ab initio calculations of quantum particles interacting with a quantized electromagnetic field. We present a hierarchy of density-functional-type theories that describe the interaction of charged particles with photons and introduce the appropriate Kohn-Sham schemes. We show how the evolution of a system described by quantum electrodynamics in Coulomb gauge is uniquely determined by its initial state and two reduced quantities. These two fundamental observables, the polarization of the Dirac field and the vector potential of the photon field, can be calculated by solving two coupled, nonlinear evolution equations without the need to explicitly determine the (numerically infeasible) many-body wave function of the coupled quantum system. To find reliable approximations to the implicit functionals, we present the appropriate Kohn-Sham construction. In the nonrelativistic limit, this density-functional-type theory of quantum electrodynamics reduces to the density-functional reformulation of the Pauli-Fierz Hamiltonian, which is based on the current density of the electrons and the vector potential of the photon field. By making further approximations, e.g., restricting the allowed modes of the photon field, we derive further density-functional-type theories of coupled matter-photon systems for the corresponding approximate Hamiltonians. In the limit of only two sites and one mode we deduce the appropriate effective theory for the two-site Hubbard model coupled to one photonic mode. This model system is used to illustrate the basic ideas of a density-functional reformulation in great detail and we present the exact Kohn-Sham potentials for our coupled matter-photon model system.
Kendon, Viv
2014-12-04
Quantum versions of random walks have diverse applications that are motivating experimental implementations as well as theoretical studies. Recent results showing quantum walks are “universal for quantum computation” relate to algorithms, to be run on quantum computers. We consider whether an experimental implementation of a quantum walk could provide useful computation before we have a universal quantum computer.
NASA Astrophysics Data System (ADS)
Sych, Denis; Leuchs, Gerd
2015-12-01
Classical physics allows for the existence of pairs of absolutely identical systems. Pairwise application of identical measurements to each of those systems always leads to exactly alike results irrespectively of the choice of measurements. Here we ask a question how the picture looks like in the quantum domain. Surprisingly, we get a counterintuitive outcome. Pairwise application of identical (but a priori unknown) measurements cannot always lead to exactly alike results. We interpret this as quantum uniqueness—a feature that has no classical analog.
Lincoln, Don
2014-10-24
The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isn’t empty at all – it’s a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs “quantum foam.” In this video, Fermilab’s Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.
Effect of the shape on the spin state and exchange in quantum dots. Feynman path integral analysis
Shevkunov, S. V.
2015-05-15
The ab initio computer simulation of the mixed quantum states of 1–5-nm model ellipsoid quantum dots with “soft” walls containing two and three quantum-indistinguishable nonrelativistic electrons has been performed by the path integral method. The calculation has been carried out beyond the single-electron and mean-field approximations with the fundamentally exact inclusion of Coulomb and exchange correlations of all orders and the spin variable. Distributions over the eigenfunctions of the spin-squared operator, as well as the equilibrium spin numbers, have been obtained depending on the shape of a quantum dot and the temperature. The complete set of basis functions symmetrized in permutations according to the spin of the system has been obtained by application of the Young symmetry operators. The dependence of the energy on the shape of the quantum dot corresponds to the negative sign of the surface tension at its boundary. The calculation indicates that the spin magnetic susceptibility in the system of two electrons decreases strongly for spherical quantum dots (“pairing” of spins) and the temperature dependences have a pronounced maximum whose position depends on the shape of the quantum dot. For three electrons in an oblate quantum dot, the inversion of the energy levels of spin states is observed and affects the spin magnetic susceptibility. The results indicate a strong dependence of the energy of collective spin states of electrons on the detailed inclusion of exchange and Coulomb spatial correlations.
Quantum control limited by quantum decoherence
Xue, Fei; Sun, C. P.; Yu, S. X.
2006-01-15
We describe quantum controllability under the influences of the quantum decoherence induced by the quantum control itself. It is shown that, when the controller is considered as a quantum system, it will entangle with its controlled system and then cause quantum decoherence in the controlled system. In competition with this induced decoherence, the controllability will be limited by some uncertainty relation in a well-armed quantum control process. In association with the phase uncertainty and the standard quantum limit, a general model is studied to demonstrate the possibility of realizing a decoherence-free quantum control with a finite energy within a finite time. It is also shown that if the operations of quantum control are to be determined by the initial state of the controller, then due to the decoherence which results from the quantum control itself, there exists a low bound for quantum controllability.
NASA Astrophysics Data System (ADS)
Fine, Boris V.
2009-11-01
This work describes the statistics for the occupation numbers of quantum levels in a large isolated quantum system, where all possible superpositions of eigenstates are allowed provided all these superpositions have the same fixed energy. Such a condition is not equivalent to the conventional microcanonical condition because the latter limits the participating eigenstates to a very narrow energy window. The statistics is obtained analytically for both the entire system and its small subsystem. In a significant departure from the Boltzmann-Gibbs statistics, the average occupation numbers of quantum states exhibit in the present case weak algebraic dependence on energy. In the macroscopic limit, this dependence is routinely accompanied by the condensation into the lowest-energy quantum state. This work contains initial numerical tests of the above statistics for finite systems and also reports the following numerical finding: when the basis states of large but finite random matrix Hamiltonians are expanded in terms of eigenstates, the participation of eigenstates in such an expansion obeys the newly obtained statistics. The above statistics might be observable in small quantum systems, but for the macroscopic systems, it rather re-enforces doubts about self-sufficiency of nonrelativistic quantum mechanics for justifying the Boltzmann-Gibbs equilibrium.
Exploring the propagation of relativistic quantum wavepackets in the trajectory-based formulation
NASA Astrophysics Data System (ADS)
Tsai, Hung-Ming; Poirier, Bill
2016-03-01
In the context of nonrelativistic quantum mechanics, Gaussian wavepacket solutions of the time-dependent Schrödinger equation provide useful physical insight. This is not the case for relativistic quantum mechanics, however, for which both the Klein-Gordon and Dirac wave equations result in strange and counterintuitive wavepacket behaviors, even for free-particle Gaussians. These behaviors include zitterbewegung and other interference effects. As a potential remedy, this paper explores a new trajectory-based formulation of quantum mechanics, in which the wavefunction plays no role [Phys. Rev. X, 4, 040002 (2014)]. Quantum states are represented as ensembles of trajectories, whose mutual interaction is the source of all quantum effects observed in nature—suggesting a “many interacting worlds” interpretation. It is shown that the relativistic generalization of the trajectory-based formulation results in well-behaved free-particle Gaussian wavepacket solutions. In particular, probability density is positive and well-localized everywhere, and its spatial integral is conserved over time—in any inertial frame. Finally, the ensemble-averaged wavepacket motion is along a straight line path through spacetime. In this manner, the pathologies of the wave-based relativistic quantum theory, as applied to wavepacket propagation, are avoided.
Sassoli de Bianchi, Massimiliano
2013-09-15
In a letter to Born, Einstein wrote [42]: “Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the ‘old one.’ I, at any rate, am convinced that He does not throw dice.” In this paper we take seriously Einstein’s famous metaphor, and show that we can gain considerable insight into quantum mechanics by doing something as simple as rolling dice. More precisely, we show how to perform measurements on a single die, to create typical quantum interference effects, and how to connect (entangle) two identical dice, to maximally violate Bell’s inequality. -- Highlights: •Rolling a die is a quantum process admitting a Hilbert space representation. •Rolling experiments with a single die can produce interference effects. •Two connected dice can violate Bell’s inequality. •Correlations need to be created by the measurement, to violate Bell’s inequality.
Visser, M. )
1991-01-15
This paper presents an application of quantum-mechanical principles to a microscopic variant of the traversable wormholes recently introduced by Morris and Thorne. The analysis, based on the surgical grafting of two Reissner-Nordstroem spacetimes, proceeds by using a minisuperspace model to approximate the geometry of these wormholes. The thin shell'' formalism is applied to this minisuperspace model to extract the effective Lagrangian appropriate to this one-degree-of-freedom system. This effective Lagrangian is then quantized and the wave function for the wormhole is explicitly exhibited. A slightly more general class of wormholes---corresponding to the addition of some dust'' to the wormhole throat---is analyzed by recourse to WKB techniques. In all cases discussed in this paper, the expectation value of the wormhole radius is calculated to be of the order of the Planck length. Accordingly, though these quantum wormholes are of considerable theoretical interest they do not appear to be useful as a means for interstellar travel. The results of this paper may also have a bearing on the question of topological fluctuations in quantum gravity. These calculations serve to suggest that topology-changing effects might in fact be {ital suppressed} by quantum-gravity effects.
NASA Astrophysics Data System (ADS)
Cheon, Taksu; Tsutsui, Izumi; Fülöp, Tamás
2004-09-01
We show that the point interactions on a line can be utilized to provide U(2) family of qubit operations for quantum information processing. Qubits are realized as states localized in either side of the point interaction which represents a controllable gate. The qubit manipulation proceeds in a manner analogous to the operation of an abacus.
NASA Astrophysics Data System (ADS)
Goradia, Shantilal
2009-11-01
The continuing search for quantum gravity and never ending attempts to unify gravity with other forces of nature represent tremendous waste of public and private funds directing students' energy towards non-creative manipulative work instead of learning from the scientific creativity in Einstein's 1919 paper that unifies gravity with nuclear force. It reflects Einstein's 1919 jump beyond his own 1915 theory of gravity, including that of Newton as implicitly demanded by Newton in 1686. Einstein corrected and retracted his 1917 introduction of cosmological constant in 1919. Dislike of the fact that Einstein did not use quantum mechanics to prove his point has no real value now, because we will use key ingredients (Planck scale and probabilistic aspect) of quantum mechanics and show that they reach the same conclusion. Newton explained the solar system known after Kepler. Likewise, our quantum mechanical approach explains the strong coupling as well the solar system and shows new horizons, otherwise unexplained. Explanation of unexplained observations need no prediction per Hawking, and obviously otherwise.
NASA Technical Reports Server (NTRS)
Dowling, Jonathan P.
2000-01-01
Recently, several researchers, including yours truly, have been able to demonstrate theoretically that quantum photon entanglement has the potential to also revolutionize the entire field of optical interferometry, by providing many orders of magnitude improvement in interferometer sensitivity. The quantum entangled photon interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like 1/Sqrt[N], where N is the number of particles (photons, electrons, atoms, neutrons) passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of Sqrt[N] (square root of N) to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical (laser) interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. Applications are to tests of General Relativity such as ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively.
Faraggi, A.E.; Matone, M.
1998-01-09
We show that the quantum Hamilton-Jacobi equation can be written in the classical form with the spatial derivative {partial_derivative}{sub q} replaced by {partial_derivative}{sub q} with dq = dq/{radical}1{minus}{beta}{sup 2}(q), where {beta}{sup 2}(q) is strictly related to the quantum potential. This can be seen as the opposite of the problem of finding the wave function representation of classical mechanics as formulated by Schiller and Rosen. The structure of the above {open_quotes}quantum transformation{close_quotes}, related to the recently formulated equivalence principle, indicates that the potential deforms space geometry. In particular, a result by Flanders implies that both W(q) = V(q) {minus} E and the quantum potential Q are proportional to the curvatures {kappa}{sub W} and {kappa}{sub Q} which arise as natural invariants in an equivalence problem for curves in the projective line. In this formulation the Schroedinger equation takes the geometrical form ({partial_derivative}{sub q}{sup 2} + {kappa}{sub W}){psi} = 0.
NASA Astrophysics Data System (ADS)
Lanzagorta, Marco O.; Gomez, Richard B.; Uhlmann, Jeffrey K.
2003-08-01
In recent years, computer graphics has emerged as a critical component of the scientific and engineering process, and it is recognized as an important computer science research area. Computer graphics are extensively used for a variety of aerospace and defense training systems and by Hollywood's special effects companies. All these applications require the computer graphics systems to produce high quality renderings of extremely large data sets in short periods of time. Much research has been done in "classical computing" toward the development of efficient methods and techniques to reduce the rendering time required for large datasets. Quantum Computing's unique algorithmic features offer the possibility of speeding up some of the known rendering algorithms currently used in computer graphics. In this paper we discuss possible implementations of quantum rendering algorithms. In particular, we concentrate on the implementation of Grover's quantum search algorithm for Z-buffering, ray-tracing, radiosity, and scene management techniques. We also compare the theoretical performance between the classical and quantum versions of the algorithms.
Ultrafast free electron quantum optics
NASA Astrophysics Data System (ADS)
Becker, Maria Gabriel
Free electron quantum optics is an emerging sub-field of physics that uses laser light, often in combination with nano-structures, to manipulate electrons in free space. Integration of femtosecond lasers into this technology is facilitating the move of free electron quantum optics into the ultrafast regime. A vision for this technology is ultrahigh temporal resolution in free electron time-of-flight experiments. Such a system would make fundamental physics studies involving small forces accessible that are not feasible with current technology. Realization of this vision will require an ultrafast source and an ultrafast detection scheme. Tungsten nano-tip sources capable of generating sub-100 fs electron pulses are already in use in our lab. Elsewhere, this type of source has been reported to emit on a sub-cycle timescale. Following up on a proposed scheme for observing sub-cycle emission, a two-color interferometer has been built and pump-probe electron emission measurements have been performed. Other efforts to develop ultrafast sources have involved implementing additional control parameters. GaAs has been investigated as a possible ultrafast source of spin-polarized electrons, and tungsten nano-tips have been modified with an ion beam to create a double tip source. Spin control and transverse separation control are expected to make studies of Pauli degeneracy pressure possible. The temporal resolution of current electronic particle detectors is ~1 ns. Schemes involving the interaction of laser pulses with nanostructures could improve this resolution by several orders of magnitude. As a first step towards a femtosecond electron switch, the temporal resolution of a nano-fabricated plasmonic antenna has been measured in a femtosecond pump-probe experiment. The possibility of an ultrafast diffraction switch has also been analyzed for nonrelativistic and relativistic electrons. In an application of a free electron time-of-flight system, the prediction of
Quantum roulette: an extended quantum strategy
NASA Astrophysics Data System (ADS)
Wang, Xiang-Bin; Kwek, L. C.; Oh, C. H.
2000-12-01
In a recent paper, Meyer demonstrated that with a quantum computer, an analogous zero-sum classically strategic game played with quantum strategy essentially become a bias game under a mixture of quantum and classical strategy. To illustrate his point, Meyer used a quantum coin tossing event. In this Letter, we generalize Meyer's argument to an N-state game.
Effects of a scalar scaling field on quantum mechanics
NASA Astrophysics Data System (ADS)
Benioff, Paul
2016-07-01
This paper describes the effects of a complex scalar scaling field on quantum mechanics. The field origin is an extension of the gauge freedom for basis choice in gauge theories to the underlying scalar field. The extension is based on the idea that the value of a number at one space time point does not determine the value at another point. This, combined with the description of mathematical systems as structures of different types, results in the presence of separate number fields and vector spaces as structures, at different space time locations. Complex number structures and vector spaces at each location are scaled by a complex space time dependent scaling factor. The effect of this scaling factor on several physical and geometric quantities has been described in other work. Here the emphasis is on quantum mechanics of one and two particles, their states and properties. Multiparticle states are also briefly described. The effect shows as a complex, nonunitary, scalar field connection on a fiber bundle description of nonrelativistic quantum mechanics. The lack of physical evidence for the presence of this field so far means that the coupling constant of this field to fermions is very small. It also means that the gradient of the field must be very small in a local region of cosmological space and time. Outside this region, there are no restrictions on the field gradient.
Quantum state and quantum entanglement protection using quantum measurements
NASA Astrophysics Data System (ADS)
Wang, Shuchao; Li, Ying; Wang, Xiangbin; Kwek, Leong Chuan; Yu, Zongwen; Zou, Wenjie
2015-03-01
The time evolution of some quantum states can be slowed down or even stopped under frequent measurements. This is the usual quantum Zeno effect. Here we report an operator quantum Zeno effect, in which the evolution of some physical observables is slowed down through measurements even though thequantum state changes randomly with time. Based on the operator quantum Zeno effect, we show how we can protect quantum information from decoherence with two-qubit measurements, realizable with noisy two-qubit interactions. Besides, we report the quantum entanglement protection using weak measurement and measurement reversal scheme. Exposed in the nonzero temperature environment, a quantum system can both lose and gain excitations by interacting with the environment. In this work, we show how to optimally protect quantum states and quantum entanglement in such a situation based on measurement reversal from weak measurement. In particular, we present explicit formulas of protection. We find that this scheme can circumvent the entanglement sudden death in certain conditions.
NASA Astrophysics Data System (ADS)
Reinisch, Gilbert C.; Gazeau, Maxime
2016-07-01
In this paper we consider a basic two-level nonlinear quantum model consisting in a two-particle interacting bound-state system. It is described by means of two different approaches: i) the mean-field stationary nonlinear Schrödinger-Poisson equation with classical Coulomb interaction and harmonic potential; ii) the linear quantum electrodynamics Hamiltonian of a quantized field coupled to two fixed charges. Computing numerically the ground state and the first excited state about the maximum eigenstate overlap (which is not zero because of eigenstate non-orthogonality), we numerically demonstrate that these two descriptions coincide at first order. As a consequence, a specific definition of the fine-structure constant α is provided within 99.95% accuracy by the present first-order non-relativistic and nonlinear quantum description. This result also means that the internal Coulomb interaction commutes with external particle confinement for the calculation of the ground state. Consequently peculiar nonlinear quantum properties become observable (an experiment with GaAs quantum-dot helium is suggested).
On the complexity of classical and quantum algorithms for numerical problems in quantum mechanics
NASA Astrophysics Data System (ADS)
Bessen, Arvid J.
information cost of computing the evolution for starting states from these spaces is tractable, i.e. the cost does not grow exponentially with the dimension of the problem. Finally we study a computational problem from lattice quantum chromodynamics (QCD). In most popular algorithms that treat problems in QCD the (gauged) Dirac matrix has to be inverted numerous times. Since this matrix is large, sparse, and ill-conditioned, iterative approaches have to be used. Unfortunately a direct application of methods like conjugate gradient (CC) or minimal residual algorithms seem to give poor performance in practice. We study a newly proposed multigrid method, adaptive smoothed aggregation [29], that has promise to overcome these difficulties We show that while classical CG's convergence becomes worse as the matrix becomes almost singular, adaptive smoothed aggregation will still perform well.
Efficient quantum walk on a quantum processor.
Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L; Wang, Jingbo B; Matthews, Jonathan C F
2016-01-01
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor. PMID:27146471
Efficient quantum walk on a quantum processor
NASA Astrophysics Data System (ADS)
Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.
2016-05-01
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.
Efficient quantum walk on a quantum processor.
Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L; Wang, Jingbo B; Matthews, Jonathan C F
2016-05-05
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.
Efficient quantum walk on a quantum processor
Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.
2016-01-01
The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor. PMID:27146471
Quantum error correction for quantum memories
NASA Astrophysics Data System (ADS)
Terhal, Barbara M.
2015-04-01
Active quantum error correction using qubit stabilizer codes has emerged as a promising, but experimentally challenging, engineering program for building a universal quantum computer. In this review the formalism of qubit stabilizer and subsystem stabilizer codes and their possible use in protecting quantum information in a quantum memory are considered. The theory of fault tolerance and quantum error correction is reviewed, and examples of various codes and code constructions, the general quantum error-correction conditions, the noise threshold, the special role played by Clifford gates, and the route toward fault-tolerant universal quantum computation are discussed. The second part of the review is focused on providing an overview of quantum error correction using two-dimensional (topological) codes, in particular, the surface code architecture. The complexity of decoding and the notion of passive or self-correcting quantum memories are discussed. The review does not focus on a particular technology but discusses topics that will be relevant for various quantum technologies.
Manipulation of quantum evolution
NASA Technical Reports Server (NTRS)
Cabera, David Jose Fernandez; Mielnik, Bogdan
1994-01-01
The free evolution of a non-relativistic charged particle is manipulated using time-dependent magnetic fields. It is shown that the application of a programmed sequence of magnetic pulses can invert the free evolution process, forcing an arbitrary wave packet to 'go back in time' to recover its past shape. The possibility of more general operations upon the Schrodinger wave packet is discussed.
Quantum random walks using quantum accelerator modes
Ma, Z.-Y.; Burnett, K.; D'Arcy, M. B.; Gardiner, S. A.
2006-01-15
We discuss the use of high-order quantum accelerator modes to achieve an atom optical realization of a biased quantum random walk. We first discuss how one can create coexistent quantum accelerator modes, and hence how momentum transfer that depends on the atoms' internal state can be achieved. When combined with microwave driving of the transition between the states, a different type of atomic beam splitter results. This permits the realization of a biased quantum random walk through quantum accelerator modes.
Kaminker, A.D.; Levenfish, K.P.; Yakovlev, D.G. ); Amsterdamski, P.; Haensel, P. )
1992-10-15
A general formalism is developed for calculating the neutrino emissivities of synchrotron and {ital e}{sup {minus}}{ital e+} annihilation radiations in a plasma in the presence of a large magnetic field {ital B}{similar to}10{sup 12}--10{sup 14} G. As a first step, the formalism is used to calculate the synchrotron and annihilation radiations from a nonrelativistic electron plasma (density {rho}{approx lt}10{sup 6} g cm{sup {minus}3}, temperature {ital T}{approx lt}6{times}10{sup 9} K) including the cases of nondegenerate and degenerate electrons, and of quantizing and nonquantizing magnetic fields. We conclude that these processes can be important for neutrino production in a hot plasma of neutron star envelopes.
NASA Astrophysics Data System (ADS)
Adams, Allan; Carr, Lincoln D.; Schaefer, Thomas; Steinberg, Peter; Thomas, John E.
2013-04-01
The last few years have witnessed a dramatic convergence of three distinct lines of research concerned with different kinds of extreme quantum matter. Two of these involve new quantum fluids that can be studied in the laboratory, ultracold quantum gases and quantum chromodynamics (QCD) plasmas. Even though these systems involve vastly different energy scales, the physical properties of the two quantum fluids are remarkably similar. The third line of research is based on the discovery of a new theoretical tool for investigating the properties of extreme quantum matter, holographic dualties. The main goal of this focus issue is to foster communication and understanding between these three fields. We proceed to describe each in more detail. Ultracold quantum gases offer a new paradigm for the study of nonperturbative quantum many-body physics. With widely tunable interaction strength, spin composition, and temperature, using different hyperfine states one can model spin-1/2 fermions, spin-3/2 fermions, and many other spin structures of bosons, fermions, and mixtures thereof. Such systems have produced a revolution in the study of strongly interacting Fermi systems, for example in the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover region, where a close collaboration between experimentalists and theorists—typical in this field—enabled ground-breaking studies in an area spanning several decades. Half-way through this crossover, when the scattering length characterizing low-energy collisions diverges, one obtains a unitary quantum gas, which is universal and scale invariant. The unitary gas has close parallels in the hydrodynamics of QCD plasmas, where the ratio of viscosity to entropy density is extremely low and comparable to the minimum viscosity conjecture, an important prediction of AdS/CFT (see below). Exciting developments in the thermodynamic and transport properties of strongly interacting Fermi gases are of broad
NASA Astrophysics Data System (ADS)
Zhu, X. P.; Zhang, Z. C.; Pushkarev, A. I.; Lei, M. K.
2016-01-01
High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.
Adiabatically implementing quantum gates
Sun, Jie; Lu, Songfeng Liu, Fang
2014-06-14
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.
Quantum gate decomposition algorithms.
Slepoy, Alexander
2006-07-01
Quantum computing algorithms can be conveniently expressed in a format of a quantum logical circuits. Such circuits consist of sequential coupled operations, termed ''quantum gates'', or quantum analogs of bits called qubits. We review a recently proposed method [1] for constructing general ''quantum gates'' operating on an qubits, as composed of a sequence of generic elementary ''gates''.
Lincoln, Don
2016-07-12
The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isnât empty at all â itâs a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs âquantum foam.â In this video, Fermilabâs Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.
Stapp, H.P.
1988-04-01
It is argued that the validity of the predictions of quantum theory in certain spin-correlation experiments entails a violation of Einstein's locality idea that no causal influence can act outside the forward light cone. First, two preliminary arguments suggesting such a violation are reviewed. They both depend, in intermediate stages, on the idea that the results of certain unperformed experiments are physically determinate. The second argument is entangled also with the problem of the meaning of physical reality. A new argument having neither of these characteristics is constructed. It is based strictly on the orthodox ideas of Bohr and Heisenberg, and has no realistic elements, or other ingredients, that are alien to orthodox quantum thinking.
NASA Astrophysics Data System (ADS)
Murdin, P.
2000-11-01
A development of quantum theory that was initiated in the 1920s by Werner Heisenberg (1901-76) and Erwin Schrödinger (1887-1961). The theory drew on a proposal made in 1925 Prince Louis de Broglie (1892-1987), that particles have wavelike properties (the wave-particle duality) and that an electron, for example, could in some respects be regarded as a wave with a wavelength that depended on its mo...
Quantum mechanical reality according to Copenhagen 2.0
NASA Astrophysics Data System (ADS)
Din, Allan M.
2016-05-01
The long-standing conceptual controversies concerning the interpretation of nonrelativistic quantum mechanics are argued, on one hand, to be due to its incompleteness, as affirmed by Einstein. But on the other hand, it appears to be possible to complete it at least partially, as Bohr might have appreciated it, in the framework of its standard mathematical formalism with observables as appropriately defined self-adjoint operators. This completion of quantum mechanics is based on the requirement on laboratory physics to be effectively confined to a bounded space region and on the application of the von Neumann deficiency theorem to properly define a set of self-adjoint extensions of standard observables, e.g. the momenta and the Hamiltonian, in terms of certain isometries on the region boundary. This is formalized mathematically in the setting of a boundary ontology for the so-called Qbox in which the wave function acquires a supplementary dependence on a set of Additional Boundary Variables (ABV). It is argued that a certain geometric subset of the ABV parametrizing Quasi-Periodic Translational Isometries (QPTI) has a particular physical importance by allowing for the definition of an ontic wave function, which has the property of epitomizing the spatial wave function “collapse.” Concomitantly the standard wave function in an unbounded geometry is interpreted as an epistemic wave function, which together with the ontic QPTI wave function gives rise to the notion of two-wave duality, replacing the standard concept of wave-particle duality. More generally, this approach to quantum physics in a bounded geometry provides a novel analytical basis for a better understanding of several conceptual notions of quantum mechanics, including reality, nonlocality, entanglement and Heisenberg’s uncertainty relation. The scope of this analysis may be seen as a foundational update of the multiple versions 1.x of the Copenhagen interpretation of quantum mechanics, which is
Efficient Quantum Information Processing via Quantum Compressions
NASA Astrophysics Data System (ADS)
Deng, Y.; Luo, M. X.; Ma, S. Y.
2016-01-01
Our purpose is to improve the quantum transmission efficiency and reduce the resource cost by quantum compressions. The lossless quantum compression is accomplished using invertible quantum transformations and applied to the quantum teleportation and the simultaneous transmission over quantum butterfly networks. New schemes can greatly reduce the entanglement cost, and partially solve transmission conflictions over common links. Moreover, the local compression scheme is useful for approximate entanglement creations from pre-shared entanglements. This special task has not been addressed because of the quantum no-cloning theorem. Our scheme depends on the local quantum compression and the bipartite entanglement transfer. Simulations show the success probability is greatly dependent of the minimal entanglement coefficient. These results may be useful in general quantum network communication.
Stapp, Henry
2011-11-10
Robert Griffiths has recently addressed, within the framework of a ‘consistent quantum theory’ (CQT) that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues, on the basis of his examination of certain arguments that claim to demonstrate the existence of such nonlocal influences, that such influences do not exist. However, his examination was restricted mainly to hidden-variable-based arguments that include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by attributing to the system properties alien to that system. Hence Griffiths’ rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his ‘consistent quantum theory’ shows that the cited proof is valid within that restrictive framework. This necessary existence, within the ‘consistent’ framework, of long range essentially instantaneous influences refutes the claim made by Griffiths that his ‘consistent’ framework is superior to the orthodox quantum theory of von Neumann because it does not entail instantaneous influences. An added section responds to Griffiths’ reply, which cites a litany of ambiguities that seem to restrict, devastatingly, the scope of his CQT formalism, apparently to buttress his claim that my use of that formalism to validate the nonlocality theorem is flawed. But the
Relativistic corrections to the pair Bc-meson production in e+e- annihilation
NASA Astrophysics Data System (ADS)
Karyasov, A. A.; Martynenko, A. P.; Martynenko, F. A.
2016-10-01
Relativistic corrections to the pair Bc-meson production in e+e--annihilation are calculated. We investigate a production of pair pseudoscalar, vector and pseudoscalar+vector Bc-mesons in the leading order perturbative quantum chromodynamics and relativistic quark model. Relativistic expressions of the pair production cross sections are obtained. Their numerical evaluation shows that relativistic effects in the production amplitudes and bound state wave functions three times reduce nonrelativistic results at the center-of-mass energy s = 22 GeV.
Evidence for the color-octet mechanism from CERN LEP2 gamma gamma --> J/psi + X Data.
Klasen, Michael; Kniehl, Bernd A; Mihaila, Luminiţa N; Steinhauser, Matthias
2002-07-15
We present theoretical predictions for the transverse-momentum distribution of J/psi mesons promptly produced in gammagamma collisions within the factorization formalism of nonrelativistic quantum chromodynamics, including the contributions from both direct and resolved photons, and we perform a conservative error analysis. The fraction of J/psi mesons from decays of bottom-flavored hadrons is estimated to be negligibly small. New data taken by the DELPHI Collaboration at LEP2 nicely confirm these predictions, while they disfavor those obtained within the traditional color-singlet model.
J/ψ plus prompt-photon associated production in two-photon collisions at next-to-leading order
NASA Astrophysics Data System (ADS)
Klasen, Michael; Kniehl, Bernd A.; Mihaila, Luminiţa N.; Steinhauser, Matthias
2005-01-01
We calculate the cross section of J/ψ plus prompt-photon inclusive production in γγ collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/ψ production, we also include the feed-down from directly produced χcJ and ψ' mesons. We discuss the analytical calculation, in particular the treatment of the various types of singularities and the NRQCD operator renormalization, in some detail. We present theoretical predictions for the future e+e- linear collider TESLA, taking into account both brems- and beamstrahlung.
J/ψ plus jet associated production in two-photon collisions at next-to-leading order
NASA Astrophysics Data System (ADS)
Klasen, M.; Kniehl, B. A.; Mihaila, L. N.; Steinhauser, M.
2005-05-01
We calculate the cross section of J/ψ plus jet inclusive production in γγ collisions at next-to-leading order within the factorization formalism of non-relativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/ψ production, we also include the feed-down from directly-produced χ and ψ mesons. We discuss the analytical calculation, in particular, the treatment of the various types of singularities and the NRQCD operator renormalization, in some detail. We present theoretical predictions for the future ee linear collider TESLA, taking into account both brems- and beamstrahlung.
NASA Astrophysics Data System (ADS)
Schmidt, Alexandre G. M.; da Silva, Ladário
2013-01-01
We quantize the gamble known as Russian roulette and we study it in two versions for two- and three-persons when: (i) players use a fully loaded quantum gun; (ii) the quantum gun has only one quantum bullet.
Interpreting quantum discord through quantum state merging
Madhok, Vaibhav; Datta, Animesh
2011-03-15
We present an operational interpretation of quantum discord based on the quantum state merging protocol. Quantum discord is the markup in the cost of quantum communication in the process of quantum state merging, if one discards relevant prior information. Our interpretation has an intuitive explanation based on the strong subadditivity of von Neumann entropy. We use our result to provide operational interpretations of other quantities like the local purity and quantum deficit. Finally, we discuss in brief some instances where our interpretation is valid in the single-copy scenario.
Quantum probability and quantum decision-making.
Yukalov, V I; Sornette, D
2016-01-13
A rigorous general definition of quantum probability is given, which is valid not only for elementary events but also for composite events, for operationally testable measurements as well as for inconclusive measurements, and also for non-commuting observables in addition to commutative observables. Our proposed definition of quantum probability makes it possible to describe quantum measurements and quantum decision-making on the same common mathematical footing. Conditions are formulated for the case when quantum decision theory reduces to its classical counterpart and for the situation where the use of quantum decision theory is necessary.
Criteria for the absence of quantum fluctuations after spontaneous symmetry breaking
Beekman, Aron J.
2015-10-15
The lowest-energy state of a macroscopic system in which symmetry is spontaneously broken, is a very stable wavepacket centered around a spontaneously chosen, classical direction in symmetry space. However, for a Heisenberg ferromagnet the quantum groundstate is exactly the classical groundstate, there are no quantum fluctuations. This coincides with seven exceptional properties of the ferromagnet, including spontaneous time-reversal symmetry breaking, a reduced number of Nambu–Goldstone modes and the absence of a thin spectrum (Anderson tower of states). Recent discoveries of other non-relativistic systems with fewer Nambu–Goldstone modes suggest these specialties apply there as well. I establish precise criteria for the absence of quantum fluctuations and all the other features. In particular, it is not sufficient that the order parameter operator commutes with the Hamiltonian. It leads to a measurably larger coherence time of superpositions in small but macroscopic systems. - Highlights: • Precise criteria for absence of quantum fluctuations in symmetry-broken states are established. • It is not sufficient that the order parameter commutes with the Hamiltonian. • Clarifies relation between quantum fluctuations and type-B Nambu–Goldstone modes. • Testable through absence of fundamental limit on maximum coherence time of macroscopic superpositions.
Relativistic quantum cryptography
Molotkov, S. N.
2011-03-15
A new protocol of quantum key distribution is proposed to transmit keys through free space. Along with quantum-mechanical restrictions on the discernibility of nonorthogonal quantum states, the protocol uses additional restrictions imposed by special relativity theory. Unlike all existing quantum key distribution protocols, this protocol ensures key secrecy for a not strictly one-photon source of quantum states and an arbitrary length of a quantum communication channel.
Quantum information does exist
NASA Astrophysics Data System (ADS)
Duwell, Armond
2008-01-01
This paper advocates a concept of quantum information whose origins can be traced to Schumacher [1995. Quantum coding. Physical Review A 51, 2738-2747]. The concept of quantum information advocated is elaborated using an analogy to Shannon's theory provided by Schumacher coding. In particular, this paper extends Timpson's [2004. Quantum information theory and the foundations of quantum mechanics. Ph.D. dissertation, University of Oxford. Preprint, quant-ph/0412063] framework for interpreting Shannon information theory to the quantum context. Entanglement fidelity is advocated as the appropriate success criterion for the reproduction of quantum information. The relationship between the Shannon theory and quantum information theory is discussed.
Interference of quantum market strategies
NASA Astrophysics Data System (ADS)
Piotrowski, Edward W.; Sładkowski, Jan; Syska, Jacek
2003-02-01
Recent development in quantum computation and quantum information theory allows to extend the scope of game theory for the quantum world. The paper is devoted to the analysis of interference of quantum strategies in quantum market games.
Quantum dynamics in phase space: Moyal trajectories 2
Braunss, G.
2013-01-15
Continuing a previous paper [G. Braunss, J. Phys. A: Math. Theor. 43, 025302 (2010)] where we had calculated Planck-Constant-Over-Two-Pi {sup 2}-approximations of quantum phase space viz. Moyal trajectories of examples with one and two degrees of freedom, we present in this paper the calculation of Planck-Constant-Over-Two-Pi {sup 2}-approximations for four examples: a two-dimensional Toda chain, the radially symmetric Schwarzschild field, and two examples with three degrees of freedom, the latter being the nonrelativistic spherically Coulomb potential and the relativistic cylinder symmetrical Coulomb potential with a magnetic field H. We show in particular that an Planck-Constant-Over-Two-Pi {sup 2}-approximation of the nonrelativistic Coulomb field has no singularity at the origin (r= 0) whereas the classical trajectories are singular at r= 0. In the third example, we show in particular that for an arbitrary function {gamma}(H, z) the expression {beta}{identical_to}p{sub z}+{gamma}(H, z) is classically ( Planck-Constant-Over-Two-Pi = 0) a constant of motion, whereas for Planck-Constant-Over-Two-Pi {ne} 0 this holds only if {gamma}(H, z) is an arbitrary polynomial of second order in z. This statement is shown to extend correspondingly to a cylinder symmetrical Schwarzschild field with a magnetic field. We exhibit in detail a number of properties of the radially symmetric Schwarzschild field. We exhibit finally the problems of the nonintegrable Henon-Heiles Hamiltonian and give a short review of the regular Hilbert space representation of Moyal operators.
Quantum recurrences: probe to study quantum chaos
Saif
2000-11-01
We study the phase space of periodically modulated gravitational cavity by means of quantum recurrence phenomena. We report that the quantum recurrences serve as a tool to connect phase space of the driven system with a spectrum in the quantum domain. With the help of quantum recurrences we investigate the quasienergy spectrum of the system for a certain fixed modulation strength. In addition, we study transition of spectrum from discrete to continuum as a function of modulation strength. PMID:11101963
Quantum teleportation of optical quantum gates.
Bartlett, Stephen D; Munro, William J
2003-03-21
We show that a universal set of gates for quantum computation with optics can be quantum teleported through the use of EPR entangled states, homodyne detection, and linear optics and squeezing operations conditioned on measurement outcomes. This scheme may be used for fault-tolerant quantum computation in any optical scheme (qubit or continuous-variable). The teleportation of nondeterministic nonlinear gates employed in linear optics quantum computation is discussed.
Quantum theory of extended particle dynamics in the presence of EM radiation-reaction
NASA Astrophysics Data System (ADS)
Cremaschini, Claudio; Tessarotto, Massimo
2015-08-01
In this paper a trajectory-based relativistic quantum wave equation is established for extended charged spinless particles subject to the action of the electromagnetic (EM) radiation-reaction (RR) interaction. The quantization pertains the particle dynamics, in which both the external and self EM fields are treated classically. The new equation proposed here is referred to as the RR quantum wave equation. This is shown to be an evolution equation for a complex scalar quantum wave function and to be realized by a first-order PDE with respect to a quantum proper time s . The latter is uniquely prescribed by representing the RR quantum wave equation in terms of the corresponding quantum hydrodynamic equations and introducing a parametrization in terms of Lagrangian paths associated with the quantum fluid velocity. Besides the explicit proper time dependence, the theory developed here exhibits a number of additional notable features. First, the wave equation is variational and is consistent with the principle of manifest covariance. Second, it permits the definition of a strictly positive 4-scalar quantum probability density on the Minkowski space-time, in terms of which a flow-invariant probability measure is established. Third, the wave equation is non-local, due to the characteristic EM RR retarded interaction. Fourth, the RR wave equation recovers the Schrödinger equation in the non-relativistic limit and the customary Klein-Gordon wave equation when the EM RR is negligible or null. Finally, the consistency with the classical RR Hamilton-Jacobi equation is established in the semi-classical limit.
Observation of quantum particles on a large space-time scale
NASA Astrophysics Data System (ADS)
Landau, L. J.
1994-10-01
A quantum particle observed on a sufficiently large space-time scale can be described by means of classical particle trajectories. The joint distribution for large-scale multiple-time position and momentum measurements on a nonrelativistic quantum particle moving freely in R v is given by straight-line trajectories with probabilities determined by the initial momentum-space wavefunction. For large-scale toroidal and rectangular regions the trajectories are geodesics. In a uniform gravitational field the trajectories are parabolas. A quantum counting process on free particles is also considered and shown to converge in the large-space-time limit to a classical counting process for particles with straight-line trajectories. If the quantum particle interacts weakly with its environment, the classical particle trajectories may undergo random jumps. In the random potential model considered here, the quantum particle evolves according to a reversible unitary one-parameter group describing elastic scattering off static randomly distributed impurities (a quantum Lorentz gas). In the large-space-time weak-coupling limit a classical stochastic process is obtained with probability one and describes a classical particle moving with constant speed in straight lines between random jumps in direction. The process depends only on the ensemble value of the covariance of the random field and not on the sample field. The probability density in phase space associated with the classical stochastic process satisfies the linear Boltzmann equation for the classical Lorentz gas, which, in the limit h→0, goes over to the linear Landau equation. Our study of the quantum Lorentz gas is based on a perturbative expansion and, as in other studies of this system, the series can be controlled only for small values of the rescaled time and for Gaussian random fields. The discussion of classical particle trajectories for nonrelativistic particles on a macroscopic spacetime scale applies also to
Quantum Steganography and Quantum Error-Correction
ERIC Educational Resources Information Center
Shaw, Bilal A.
2010-01-01
Quantum error-correcting codes have been the cornerstone of research in quantum information science (QIS) for more than a decade. Without their conception, quantum computers would be a footnote in the history of science. When researchers embraced the idea that we live in a world where the effects of a noisy environment cannot completely be…
Quantum Hall effect in quantum electrodynamics
Penin, Alexander A.
2009-03-15
We consider the quantum Hall effect in quantum electrodynamics and find a deviation from the quantum-mechanical prediction for the Hall conductivity due to radiative antiscreening of electric charge in an external magnetic field. A weak dependence of the universal von Klitzing constant on the magnetic field strength, which can possibly be observed in a dedicated experiment, is predicted.
NASA Astrophysics Data System (ADS)
Grossert, Christopher; Leder, Martin; Weitz, Martin
2016-10-01
The dispersion relation of ultracold atoms in variably shaped optical lattices can be tuned to resemble that of a relativistic particle, i.e. be linear instead of the usual nonrelativistic quadratic dispersion relation of a free atom. Cold atoms in such a lattice can be used to carry out quantum simulations of relativistic wave equation predictions. We begin this article by describing a Raman technique that allows to selectively load atoms into a desired Bloch band of the lattice near a band crossing. Subsequently, we review two recent experiments with quasirelativistic rubidium atoms in a bichromatic lattice, demonstrating the analogues of Klein tunnelling and Veselago lensing with ultracold atoms, respectively.
NASA Astrophysics Data System (ADS)
Lidar, Daniel A.; Brun, Todd A.
2013-09-01
Prologue; Preface; Part I. Background: 1. Introduction to decoherence and noise in open quantum systems Daniel Lidar and Todd Brun; 2. Introduction to quantum error correction Dave Bacon; 3. Introduction to decoherence-free subspaces and noiseless subsystems Daniel Lidar; 4. Introduction to quantum dynamical decoupling Lorenza Viola; 5. Introduction to quantum fault tolerance Panos Aliferis; Part II. Generalized Approaches to Quantum Error Correction: 6. Operator quantum error correction David Kribs and David Poulin; 7. Entanglement-assisted quantum error-correcting codes Todd Brun and Min-Hsiu Hsieh; 8. Continuous-time quantum error correction Ognyan Oreshkov; Part III. Advanced Quantum Codes: 9. Quantum convolutional codes Mark Wilde; 10. Non-additive quantum codes Markus Grassl and Martin Rötteler; 11. Iterative quantum coding systems David Poulin; 12. Algebraic quantum coding theory Andreas Klappenecker; 13. Optimization-based quantum error correction Andrew Fletcher; Part IV. Advanced Dynamical Decoupling: 14. High order dynamical decoupling Zhen-Yu Wang and Ren-Bao Liu; 15. Combinatorial approaches to dynamical decoupling Martin Rötteler and Pawel Wocjan; Part V. Alternative Quantum Computation Approaches: 16. Holonomic quantum computation Paolo Zanardi; 17. Fault tolerance for holonomic quantum computation Ognyan Oreshkov, Todd Brun and Daniel Lidar; 18. Fault tolerant measurement-based quantum computing Debbie Leung; Part VI. Topological Methods: 19. Topological codes Héctor Bombín; 20. Fault tolerant topological cluster state quantum computing Austin Fowler and Kovid Goyal; Part VII. Applications and Implementations: 21. Experimental quantum error correction Dave Bacon; 22. Experimental dynamical decoupling Lorenza Viola; 23. Architectures Jacob Taylor; 24. Error correction in quantum communication Mark Wilde; Part VIII. Critical Evaluation of Fault Tolerance: 25. Hamiltonian methods in QEC and fault tolerance Eduardo Novais, Eduardo Mucciolo and
Quantum Walk Schemes for Universal Quantum Computation
NASA Astrophysics Data System (ADS)
Underwood, Michael S.
Random walks are a powerful tool for the efficient implementation of algorithms in classical computation. Their quantum-mechanical analogues, called quantum walks, hold similar promise. Quantum walks provide a model of quantum computation that has recently been shown to be equivalent in power to the standard circuit model. As in the classical case, quantum walks take place on graphs and can undergo discrete or continuous evolution, though quantum evolution is unitary and therefore deterministic until a measurement is made. This thesis considers the usefulness of continuous-time quantum walks to quantum computation from the perspectives of both their fundamental power under various formulations, and their applicability in practical experiments. In one extant scheme, logical gates are effected by scattering processes. The results of an exhaustive search for single-qubit operations in this model are presented. It is shown that the number of distinct operations increases exponentially with the number of vertices in the scattering graph. A catalogue of all graphs on up to nine vertices that implement single-qubit unitaries at a specific set of momenta is included in an appendix. I develop a novel scheme for universal quantum computation called the discontinuous quantum walk, in which a continuous-time quantum walker takes discrete steps of evolution via perfect quantum state transfer through small 'widget' graphs. The discontinuous quantum-walk scheme requires an exponentially sized graph, as do prior discrete and continuous schemes. To eliminate the inefficient vertex resource requirement, a computation scheme based on multiple discontinuous walkers is presented. In this model, n interacting walkers inhabiting a graph with 2n vertices can implement an arbitrary quantum computation on an input of length n, an exponential savings over previous universal quantum walk schemes. This is the first quantum walk scheme that allows for the application of quantum error correction
Multi-time wave functions for quantum field theory
Petrat, Sören; Tumulka, Roderich
2014-06-15
Multi-time wave functions such as ϕ(t{sub 1},x{sub 1},…,t{sub N},x{sub N}) have one time variable t{sub j} for each particle. This type of wave function arises as a relativistic generalization of the wave function ψ(t,x{sub 1},…,x{sub N}) of non-relativistic quantum mechanics. We show here how a quantum field theory can be formulated in terms of multi-time wave functions. We mainly consider a particular quantum field theory that features particle creation and annihilation. Starting from the particle–position representation of state vectors in Fock space, we introduce multi-time wave functions with a variable number of time variables, set up multi-time evolution equations, and show that they are consistent. Moreover, we discuss the relation of the multi-time wave function to two other representations, the Tomonaga–Schwinger representation and the Heisenberg picture in terms of operator-valued fields on space–time. In a certain sense and under natural assumptions, we find that all three representations are equivalent; yet, we point out that the multi-time formulation has several technical and conceptual advantages. -- Highlights: •Multi-time wave functions are manifestly Lorentz-covariant objects. •We develop consistent multi-time equations with interaction for quantum field theory. •We discuss in detail a particular model with particle creation and annihilation. •We show how multi-time wave functions are related to the Tomonaga–Schwinger approach. •We show that they have a simple representation in terms of operator valued fields.
Matter bounce loop quantum cosmology from F (R ) gravity
NASA Astrophysics Data System (ADS)
Odintsov, S. D.; Oikonomou, V. K.
2014-12-01
Using the reconstruction method, we investigate which F (R ) theories, with or without the presence of matter fluids, can produce the matter bounce scenario of holonomy corrected loop quantum cosmology. We focus our study in two limits of the cosmic time, the large cosmic time limit and the small cosmic time limit. For the former, we find that, in the presence of noninteracting and nonrelativistic matter, the F (R ) gravity that reproduces the late time limit of the matter bounce solution is actually the Einstein-Hilbert gravity plus a power law term. In the early time limit, since it corresponds to large spacetime curvatures, assuming that the Jordan frame is described by a general metric that, when it is conformally transformed to the Einstein frame, produces an accelerating Friedmann-Robertson-Walker metric, we find explicitly the scalar field dependence on time. After demonstrating that the solution in the Einstein frame is indeed accelerating, we calculate the spectral index derived from the Einstein frame scalar-tensor counterpart theory of the F (R ) theory and compare it with the Planck experiment data. In order to implement the resulting picture, we embed the F (R ) gravity explicitly in a loop quantum cosmology framework by introducing holonomy corrections to the F (R ) gravity. In this way, the resulting inflation picture corresponding to the F (R ) gravity can be corrected in order that it coincides to some extent with the current experimental data.
Novel Quantum Criticality in Two Dimensional Topological Phase transitions
Cho, Gil Young; Moon, Eun-Gook
2016-01-01
Topological quantum phase transitions intrinsically intertwine self-similarity and topology of many-electron wave-functions, and divining them is one of the most significant ways to advance understanding in condensed matter physics. Our focus is to investigate an unconventional class of the transitions between insulators and Dirac semimetals whose description is beyond conventional pseudo relativistic Dirac Hamiltonian. At the transition without the long-range Coulomb interaction, the electronic energy dispersion along one direction behaves like a relativistic particle, linear in momentum, but along the other direction it behaves like a non-relativistic particle, quadratic in momentum. Various physical systems ranging from TiO2-VO2 heterostructure to organic material α-(BEDT-TTF)2I3 under pressure have been proposed to have such anisotropic dispersion relation. Here, we discover a novel quantum criticality at the phase transition by incorporating the long range Coulomb interaction. Unique interplay between the Coulomb interaction and electronic critical modes enforces not only the anisotropic renormalization of the Coulomb interaction but also marginally modified electronic excitation. In connection with experiments, we investigate several striking effects in physical observables of our novel criticality. PMID:26791803
A Quantum Simulation on the Emergence of Lorentz Invariance
NASA Astrophysics Data System (ADS)
Zueco, David; Quijandría, Fernando; Blas, Diego; Pujòlas, Oriol
2014-03-01
Lorentz invariance (LI) is one of the best tested symmetries of Nature. It is natural to think that LI is a fundamental property. However, this does not need to be so. In fact, it could be an emergent symmetry in the low energy world. One motivation on Lorentz-violating theories may come from consistent non-relativistic models of gravity, where LI appears at low energies. The basic approach is by taking two interacting quantum fields. The bare (uncoupled fields) have different light velocities, say v1 and v2. The coupling tends to ``synchronize'' those velocities providing a common light velocity: the LI emergence. So far, only perturbative calculations are available. In this perturbative regime the emergence of LI is too slow. Therefore it is mandatory going beyond perturbative calculations. In this talk I will discuss that such models for emergent Lorentz Invariance can be simulated in an analog quantum simulator. In 1+1 dimensions two transmission lines coupled trough Josephson Junctions do the job. We show that the emergence can be checked by measuring photon correlations. Everything within the state of the art in circuit QED. We show that our proposal can provide a definite answer about the LI emergence hypothesis in the strong coupling regime.
The Bondons: The Quantum Particles of the Chemical Bond
Putz, Mihai V.
2010-01-01
By employing the combined Bohmian quantum formalism with the U(1) and SU(2) gauge transformations of the non-relativistic wave-function and the relativistic spinor, within the Schrödinger and Dirac quantum pictures of electron motions, the existence of the chemical field is revealed along the associate bondon particle B̶ characterized by its mass (mB̶), velocity (vB̶), charge (eB̶), and life-time (tB̶). This is quantized either in ground or excited states of the chemical bond in terms of reduced Planck constant ħ, the bond energy Ebond and length Xbond, respectively. The mass-velocity-charge-time quaternion properties of bondons’ particles were used in discussing various paradigmatic types of chemical bond towards assessing their covalent, multiple bonding, metallic and ionic features. The bondonic picture was completed by discussing the relativistic charge and life-time (the actual zitterbewegung) problem, i.e., showing that the bondon equals the benchmark electronic charge through moving with almost light velocity. It carries negligible, although non-zero, mass in special bonding conditions and towards observable femtosecond life-time as the bonding length increases in the nanosystems and bonding energy decreases according with the bonding length-energy relationship Ebond[kcal/mol]×Xbond[A0]=182019, providing this way the predictive framework in which the B̶ particle may be observed. Finally, its role in establishing the virtual states in Raman scattering was also established. PMID:21151435
Band Collapse and the Quantum Hall Effect in Graphene
Bernevig, B.Andrei; Hughes, Taylor L.; Zhang, Shou-Cheng; Chen, Han-Dong; Wu, Congjun; /Santa Barbara, KITP
2010-03-16
The recent Quantum Hall experiments in graphene have confirmed the theoretically well-understood picture of the quantum Hall (QH) conductance in fermion systems with continuum Dirac spectrum. In this paper we take into account the lattice, and perform an exact diagonalization of the Landau problem on the hexagonal lattice. At very large magnetic fields the Dirac argument fails completely and the Hall conductance, given by the number of edge states present in the gaps of the spectrum, is dominated by lattice effects. As the field is lowered, the experimentally observed situation is recovered through a phenomenon which we call band collapse. As a corollary, for low magnetic field, graphene will exhibit two qualitatively different QHE's: at low filling, the QHE will be dominated by the 'relativistic' Dirac spectrum and the Hall conductance will be odd-integer; above a certain filling, the QHE will be dominated by a non-relativistic spectrum, and the Hall conductance will span all integers, even and odd.
Quantum algorithms for quantum field theories.
Jordan, Stephen P; Lee, Keith S M; Preskill, John
2012-06-01
Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We developed a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (φ(4) 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. PMID:22654052
Quantum algorithms for quantum field theories.
Jordan, Stephen P; Lee, Keith S M; Preskill, John
2012-06-01
Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We developed a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (φ(4) 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.
Zhang, Ya; Jiang, Wei; Song, Yuan-Hong; Wang, You-Nian
2015-02-15
Isochoric heating of an aluminum target by proton beams has been studied with a two-dimensional self-consistent electromagnetic quantum-hydrodynamic model, including the nonlinear quantum effects. It is shown that most protons deposit their energy within several micrometers near the surface, and the aluminum metal target is heated up to several electron volts in tens of Mbar pressure regime within one picosecond. Comparison between electrostatic and electromagnetic cases shows that the strength of electromagnetic field is much smaller than that of the electrostatic field at initial stage but increases more rapidly and becomes larger at later time. The results show that the time evolution of electric field has a significant influence on the interaction of intense beams with a solid target, while the effect of the self-magnetic field is small for non-relativistic beams considered here.
NASA Astrophysics Data System (ADS)
Iqbal, Azhar; Abbott, Derek
2009-01-01
A quantum version of the matching pennies (MP) game is proposed that is played using an Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) setting. We construct the quantum game without using state vectors, while considering only the quantum mechanical joint probabilities relevant to the EPR-Bohm setting. We embed the classical game within the quantum game such that the classical MP game results when the quantum mechanical joint probabilities become factorizable. We report new Nash equilibria in the quantum MP game that emerge when the quantum mechanical joint probabilities maximally violate the Clauser-Horne-Shimony-Holt form of Bell’s inequality.
Universal quantum computation by discontinuous quantum walk
Underwood, Michael S.; Feder, David L.
2010-10-15
Quantum walks are the quantum-mechanical analog of random walks, in which a quantum ''walker'' evolves between initial and final states by traversing the edges of a graph, either in discrete steps from node to node or via continuous evolution under the Hamiltonian furnished by the adjacency matrix of the graph. We present a hybrid scheme for universal quantum computation in which a quantum walker takes discrete steps of continuous evolution. This ''discontinuous'' quantum walk employs perfect quantum-state transfer between two nodes of specific subgraphs chosen to implement a universal gate set, thereby ensuring unitary evolution without requiring the introduction of an ancillary coin space. The run time is linear in the number of simulated qubits and gates. The scheme allows multiple runs of the algorithm to be executed almost simultaneously by starting walkers one time step apart.
Secure quantum signatures using insecure quantum channels
NASA Astrophysics Data System (ADS)
Amiri, Ryan; Wallden, Petros; Kent, Adrian; Andersson, Erika
2016-03-01
Digital signatures are widely used in modern communication to guarantee authenticity and transferability of messages. The security of currently used classical schemes relies on computational assumptions. We present a quantum signature scheme that does not require trusted quantum channels. We prove that it is unconditionally secure against the most general coherent attacks, and show that it requires the transmission of significantly fewer quantum states than previous schemes. We also show that the quantum channel noise threshold for our scheme is less strict than for distilling a secure key using quantum key distribution. This shows that "direct" quantum signature schemes can be preferable to signature schemes relying on secret shared keys generated using quantum key distribution.
Randomness: Quantum versus classical
NASA Astrophysics Data System (ADS)
Khrennikov, Andrei
2016-05-01
Recent tremendous development of quantum information theory has led to a number of quantum technological projects, e.g. quantum random generators. This development had stimulated a new wave of interest in quantum foundations. One of the most intriguing problems of quantum foundations is the elaboration of a consistent and commonly accepted interpretation of a quantum state. Closely related problem is the clarification of the notion of quantum randomness and its interrelation with classical randomness. In this short review, we shall discuss basics of classical theory of randomness (which by itself is very complex and characterized by diversity of approaches) and compare it with irreducible quantum randomness. We also discuss briefly “digital philosophy”, its role in physics (classical and quantum) and its coupling to the information interpretation of quantum mechanics (QM).
Bender, Carl M; DeKieviet, Maarten; Klevansky, S. P.
2013-01-01
-symmetric quantum mechanics (PTQM) has become a hot area of research and investigation. Since its beginnings in 1998, there have been over 1000 published papers and more than 15 international conferences entirely devoted to this research topic. Originally, PTQM was studied at a highly mathematical level and the techniques of complex variables, asymptotics, differential equations and perturbation theory were used to understand the subtleties associated with the analytic continuation of eigenvalue problems. However, as experiments on -symmetric physical systems have been performed, a simple and beautiful physical picture has emerged, and a -symmetric system can be understood as one that has a balanced loss and gain. Furthermore, the phase transition can now be understood intuitively without resorting to sophisticated mathe- matics. Research on PTQM is following two different paths: at a fundamental level, physicists are attempting to understand the underlying mathematical structure of these theories with the long-range objective of applying the techniques of PTQM to understanding some of the outstanding problems in physics today, such as the nature of the Higgs particle, the properties of dark matter, the matter–antimatter asymmetry in the universe, neutrino oscillations and the cosmological constant; at an applied level, new kinds of -synthetic materials are being developed, and the phase transition is being observed in many physical contexts, such as lasers, optical wave guides, microwave cavities, superconducting wires and electronic circuits. The purpose of this Theme Issue is to acquaint the reader with the latest developments in PTQM. The articles in this volume are written in the style of mini-reviews and address diverse areas of the emerging and exciting new area of -symmetric quantum mechanics. PMID:23509390
Quantum computing classical physics.
Meyer, David A
2002-03-15
In the past decade, quantum algorithms have been found which outperform the best classical solutions known for certain classical problems as well as the best classical methods known for simulation of certain quantum systems. This suggests that they may also speed up the simulation of some classical systems. I describe one class of discrete quantum algorithms which do so--quantum lattice-gas automata--and show how to implement them efficiently on standard quantum computers.
NASA Astrophysics Data System (ADS)
Cook, Richard J.
1988-01-01
This paper answers the title question by giving an operational definition of quantum jumps based on measurement theory. This definition forms the basis of a theory of quantum jumps which leads to a number of testable predictions. Experiments are proposed to test the theory. The suggested experiments also test the quantum Zeno paradox, i.e., they test the proposition that frequent observation of a quantum system inhibits quantum jumps in that system.
Diagrammatic quantum mechanics
NASA Astrophysics Data System (ADS)
Kauffman, Louis H.; Lomonaco, Samuel J.
2015-05-01
This paper explores how diagrams of quantum processes can be used for modeling and for quantum epistemology. The paper is a continuation of the discussion where we began this formulation. Here we give examples of quantum networks that represent unitary transformations by dint of coherence conditions that constitute a new form of non-locality. Local quantum devices interconnected in space can form a global quantum system when appropriate coherence conditions are maintained.
NASA Astrophysics Data System (ADS)
Sun, Zhan; Wu, Xing-Gang; Zhang, Hong-Fei
2015-10-01
We present a systematical study on the prompt J /ψ production in association with a c c ¯ pair via the process, γ γ →H (c c ¯)+c +c ¯, within the framework of nonrelativistic QCD at the future high-energy e+e- collider—International Linear Collider (ILC), including both direct and feed-down contributions. For direct J /ψ production, the states with color-octet channels, especially the P3 J[8] and S1 0[8] ones, provide a dominant contribution to the production cross section, which are about 52 times over that of the color-singlet one. This is clearly shown by the transverse momentum (pt) and rapidity distributions. The feed-down contribution from ψ' and χc J (J =0 , 1, 2) is sizable, which is about 20% to the total prompt cross section. Besides the yields, we also calculate the J /ψ polarization parameter λ . In the small pt region, the polarization of the prompt J /ψ is longitudinal due to large contributions through the P3 J[8] channel, and becomes transverse in the high pt region due to the S3 1[8] channel. Thus the J /ψ production via photon-photon collisions at the ILC shall provide a useful platform for testing the color-octet mechanism.
Probabilistic Cloning and Quantum Computation
NASA Astrophysics Data System (ADS)
Gao, Ting; Yan, Feng-Li; Wang, Zhi-Xi
2004-06-01
We discuss the usefulness of quantum cloning and present examples of quantum computation tasks for which the cloning offers an advantage which cannot be matched by any approach that does not resort to quantum cloning. In these quantum computations, we need to distribute quantum information contained in the states about which we have some partial information. To perform quantum computations, we use a state-dependent probabilistic quantum cloning procedure to distribute quantum information in the middle of a quantum computation.
Single particle in quantum gravity and Braunstein-Ghosh-Severini entropy of a spin network
Rovelli, Carlo; Vidotto, Francesca
2010-02-15
Passerini and Severini have recently shown that the Braunstein-Ghosh-Severini (BGS) entropy S{sub {Gamma}}=-Tr[{rho}{sub {Gamma}}log{rho}{sub {Gamma}}] of a certain density matrix {rho}{sub {Gamma}} naturally associated to a graph {Gamma}, is maximized, among all graphs with a fixed number of links and nodes, by regular graphs. We ask if this result can play a role in quantum gravity, and be related to the apparent regularity of the physical geometry of space. We show that in loop quantum gravity the matrix {rho}{sub {Gamma}} is precisely the Hamiltonian operator (suitably normalized) of a nonrelativistic quantum particle interacting with the quantum gravitational field, if we restrict elementary area and volume eigenvalues to a fixed value. This operator provides a spectral characterization of the physical geometry, and can be interpreted as a state describing the spectral information about the geometry available when geometry is measured by its physical interaction with matter. It is then tempting to interpret its BGS entropy S{sub {Gamma}} as a genuine physical entropy: we discuss the appeal and the difficulties of this interpretation.
Lieb-Robinson Bound and the Butterfly Effect in Quantum Field Theories.
Roberts, Daniel A; Swingle, Brian
2016-08-26
As experiments are increasingly able to probe the quantum dynamics of systems with many degrees of freedom, it is interesting to probe fundamental bounds on the dynamics of quantum information. We elaborate on the relationship between one such bound-the Lieb-Robinson bound-and the butterfly effect in strongly coupled quantum systems. The butterfly effect implies the ballistic growth of local operators in time, which can be quantified with the "butterfly" velocity v_{B}. Similarly, the Lieb-Robinson velocity places a state-independent ballistic upper bound on the size of time evolved operators in nonrelativistic lattice models. Here, we argue that v_{B} is a state-dependent effective Lieb-Robinson velocity. We study the butterfly velocity in a wide variety of quantum field theories using holography and compare with free-particle computations to understand the role of strong coupling. We find that v_{B} remains constant or decreases with decreasing temperature. We also comment on experimental prospects and on the relationship between the butterfly velocity and signaling. PMID:27610843
Lieb-Robinson Bound and the Butterfly Effect in Quantum Field Theories
NASA Astrophysics Data System (ADS)
Roberts, Daniel A.; Swingle, Brian
2016-08-01
As experiments are increasingly able to probe the quantum dynamics of systems with many degrees of freedom, it is interesting to probe fundamental bounds on the dynamics of quantum information. We elaborate on the relationship between one such bound—the Lieb-Robinson bound—and the butterfly effect in strongly coupled quantum systems. The butterfly effect implies the ballistic growth of local operators in time, which can be quantified with the "butterfly" velocity vB . Similarly, the Lieb-Robinson velocity places a state-independent ballistic upper bound on the size of time evolved operators in nonrelativistic lattice models. Here, we argue that vB is a state-dependent effective Lieb-Robinson velocity. We study the butterfly velocity in a wide variety of quantum field theories using holography and compare with free-particle computations to understand the role of strong coupling. We find that vB remains constant or decreases with decreasing temperature. We also comment on experimental prospects and on the relationship between the butterfly velocity and signaling.
Quantum mechanics in non-inertial reference frames: Time-dependent rotations and loop prolongations
NASA Astrophysics Data System (ADS)
Klink, W. H.; Wickramasekara, S.
2013-09-01
This is the fourth in a series of papers on developing a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group to include transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. In previous work, we have shown that there exist representations of the Galilean line group that uphold the non-relativistic equivalence principle as well as representations that violate the equivalence principle. In these previous studies, the focus was on linear accelerations. In this paper, we undertake an extension of the formulation to include rotational accelerations. We show that the incorporation of rotational accelerations requires a class of loop prolongations of the Galilean line group and their unitary cocycle representations. We recover the centrifugal and Coriolis force effects from these loop representations. Loops are more general than groups in that their multiplication law need not be associative. Hence, our broad theoretical claim is that a Galilean quantum theory that holds in arbitrary non-inertial reference frames requires going beyond groups and group representations, the well-established framework for implementing symmetry transformations in quantum mechanics.
NASA Astrophysics Data System (ADS)
Bojowald, Martin
The universe, ultimately, is to be described by quantum theory. Quantum aspects of all there is, including space and time, may not be significant for many purposes, but are crucial for some. And so a quantum description of cosmology is required for a complete and consistent worldview. At any rate, even if we were not directly interested in regimes where quantum cosmology plays a role, a complete physical description could not stop at a stage before the whole universe is reached. Quantum theory is essential in the microphysics of particles, atoms, molecules, solids, white dwarfs and neutron stars. Why should one expect this ladder of scales to end at a certain size? If regimes are sufficiently violent and energetic, quantum effects are non-negligible even on scales of the whole cosmos; this is realized at least once in the history of the universe: at the big bang where the classical theory of general relativity would make energy densities diverge.
Quantum optics, cavity QED, and quantum optomechanics
NASA Astrophysics Data System (ADS)
Meystre, Pierre
2013-05-01
Quantum optomechanics provides a universal tool to achieve the quantum control of mechanical motion. It does that in devices spanning a vast range of parameters, with mechanical frequencies from a few Hertz to GHz, and with masses from 10-20 g to several kilos. Its underlying ideas can be traced back to the study of gravitational wave antennas, quantum optics, cavity QED and laser cooling which, when combined with the recent availability of advanced micromechanical and nanomechanical devices, opens a path to the realization of macroscopic mechanical systems that operate deep in the quantum regime. At the fundamental level this development paves the way to experiments that will lead to a more profound understanding of quantum mechanics; and from the point of view of applications, quantum optomechanical techniques will provide motion and force sensing near the fundamental limit imposed by quantum mechanics (quantum metrology) and significantly expand the toolbox of quantum information science. After a brief summary of key historical developments, the talk will give a broad overview of the current state of the art of quantum optomechanics, and comment on future prospects both in applied and in fundamental science. Work supported by NSF, ARO and the DARPA QuASAR and ORCHID programs.
NASA Astrophysics Data System (ADS)
Alvarez-Rodriguez, U.; Sanz, M.; Lamata, L.; Solano, E.
2015-07-01
Quantum information provides fundamentally different computational resources than classical information. We prove that there is no unitary protocol able to add unknown quantum states belonging to different Hilbert spaces. This is an inherent restriction of quantum physics that is related to the impossibility of copying an arbitrary quantum state, i.e., the no-cloning theorem. Moreover, we demonstrate that a quantum adder, in absence of an ancillary system, is also forbidden for a known orthonormal basis. This allows us to propose an approximate quantum adder that could be implemented in the lab. Finally, we discuss the distinct character of the forbidden quantum adder for quantum states and the allowed quantum adder for density matrices.
Expected number of quantum channels in quantum networks.
Chen, Xi; Wang, He-Ming; Ji, Dan-Tong; Mu, Liang-Zhu; Fan, Heng
2015-01-01
Quantum communication between nodes in quantum networks plays an important role in quantum information processing. Here, we proposed the use of the expected number of quantum channels as a measure of the efficiency of quantum communication for quantum networks. This measure quantified the amount of quantum information that can be teleported between nodes in a quantum network, which differs from classical case in that the quantum channels will be consumed if teleportation is performed. We further demonstrated that the expected number of quantum channels represents local correlations depicted by effective circles. Significantly, capacity of quantum communication of quantum networks quantified by ENQC is independent of distance for the communicating nodes, if the effective circles of communication nodes are not overlapped. The expected number of quantum channels can be enhanced through transformations of the lattice configurations of quantum networks via entanglement swapping. Our results can shed lights on the study of quantum communication in quantum networks.
Expected number of quantum channels in quantum networks.
Chen, Xi; Wang, He-Ming; Ji, Dan-Tong; Mu, Liang-Zhu; Fan, Heng
2015-01-01
Quantum communication between nodes in quantum networks plays an important role in quantum information processing. Here, we proposed the use of the expected number of quantum channels as a measure of the efficiency of quantum communication for quantum networks. This measure quantified the amount of quantum information that can be teleported between nodes in a quantum network, which differs from classical case in that the quantum channels will be consumed if teleportation is performed. We further demonstrated that the expected number of quantum channels represents local correlations depicted by effective circles. Significantly, capacity of quantum communication of quantum networks quantified by ENQC is independent of distance for the communicating nodes, if the effective circles of communication nodes are not overlapped. The expected number of quantum channels can be enhanced through transformations of the lattice configurations of quantum networks via entanglement swapping. Our results can shed lights on the study of quantum communication in quantum networks. PMID:26173556
Expected number of quantum channels in quantum networks
Chen, Xi; Wang, He-Ming; Ji, Dan-Tong; Mu, Liang-Zhu; Fan, Heng
2015-01-01
Quantum communication between nodes in quantum networks plays an important role in quantum information processing. Here, we proposed the use of the expected number of quantum channels as a measure of the efficiency of quantum communication for quantum networks. This measure quantified the amount of quantum information that can be teleported between nodes in a quantum network, which differs from classical case in that the quantum channels will be consumed if teleportation is performed. We further demonstrated that the expected number of quantum channels represents local correlations depicted by effective circles. Significantly, capacity of quantum communication of quantum networks quantified by ENQC is independent of distance for the communicating nodes, if the effective circles of communication nodes are not overlapped. The expected number of quantum channels can be enhanced through transformations of the lattice configurations of quantum networks via entanglement swapping. Our results can shed lights on the study of quantum communication in quantum networks. PMID:26173556
Reliable quantum communication over a quantum relay channel
Gyongyosi, Laszlo; Imre, Sandor
2014-12-04
We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.
Quantum thermodynamics of general quantum processes.
Binder, Felix; Vinjanampathy, Sai; Modi, Kavan; Goold, John
2015-03-01
Accurately describing work extraction from a quantum system is a central objective for the extension of thermodynamics to individual quantum systems. The concepts of work and heat are surprisingly subtle when generalizations are made to arbitrary quantum states. We formulate an operational thermodynamics suitable for application to an open quantum system undergoing quantum evolution under a general quantum process by which we mean a completely positive and trace-preserving map. We derive an operational first law of thermodynamics for such processes and show consistency with the second law. We show that heat, from the first law, is positive when the input state of the map majorizes the output state. Moreover, the change in entropy is also positive for the same majorization condition. This makes a strong connection between the two operational laws of thermodynamics. PMID:25871066
Quantum Dimension and Quantum Projective Spaces
NASA Astrophysics Data System (ADS)
Matassa, Marco
2014-09-01
We show that the family of spectral triples for quantum projective spaces introduced by D'Andrea and Dąbrowski, which have spectral dimension equal to zero, can be reconsidered as modular spectral triples by taking into account the action of the element K_{2rho} or its inverse. The spectral dimension computed in this sense coincides with the dimension of the classical projective spaces. The connection with the well known notion of quantum dimension of quantum group theory is pointed out.
Counterfactual quantum cryptography.
Noh, Tae-Gon
2009-12-01
Quantum cryptography allows one to distribute a secret key between two remote parties using the fundamental principles of quantum mechanics. The well-known established paradigm for the quantum key distribution relies on the actual transmission of signal particle through a quantum channel. In this Letter, we show that the task of a secret key distribution can be accomplished even though a particle carrying secret information is not in fact transmitted through the quantum channel. The proposed protocols can be implemented with current technologies and provide practical security advantages by eliminating the possibility that an eavesdropper can directly access the entire quantum system of each signal particle.
NASA Astrophysics Data System (ADS)
Viennot, David; Aubourg, Lucile
2016-02-01
We study a theoretical model of closed quasi-hermitian chain of spins which exhibits quantum analogues of chimera states, i.e. long life classical states for which a part of an oscillator chain presents an ordered dynamics whereas another part presents a disordered dynamics. For the quantum analogue, the chimera behaviour deals with the entanglement between the spins of the chain. We discuss the entanglement properties, quantum chaos, quantum disorder and semi-classical similarity of our quantum chimera system. The quantum chimera concept is novel and induces new perspectives concerning the entanglement of multipartite systems.
Counterfactual quantum cryptography.
Noh, Tae-Gon
2009-12-01
Quantum cryptography allows one to distribute a secret key between two remote parties using the fundamental principles of quantum mechanics. The well-known established paradigm for the quantum key distribution relies on the actual transmission of signal particle through a quantum channel. In this Letter, we show that the task of a secret key distribution can be accomplished even though a particle carrying secret information is not in fact transmitted through the quantum channel. The proposed protocols can be implemented with current technologies and provide practical security advantages by eliminating the possibility that an eavesdropper can directly access the entire quantum system of each signal particle. PMID:20366133
Quantum information causality.
Pitalúa-García, Damián
2013-05-24
How much information can a transmitted physical system fundamentally communicate? We introduce the principle of quantum information causality, which states the maximum amount of quantum information that a quantum system can communicate as a function of its dimension, independently of any previously shared quantum physical resources. We present a new quantum information task, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs. PMID:23745844
Multiscale quantum optical networks
NASA Astrophysics Data System (ADS)
Jaroszkiewicz, George
2007-04-01
Quantum experiments are described in terms of time-dependent networks of quantum bits, each qubit representing an elementary information gateway. The emphasis is on the signal properties of apparatus rather than on systems under observation (SUOs), with the quantum states of the theory (the labstates) representing the observer's information about the state of their apparatus, rather than of any SUO. The formalism gives an efficient quantum register description related to the formalism of quantum computation. Experiments conventionally described by the PVM and POVM formalisms are treated in identical terms, the formalism providing an efficient modular approach to quantum optics experiments of arbitrary complexity.
Lan, S-Y; Radnaev, A G; Collins, O A; Matsukevich, D N; Kennedy, T A; Kuzmich, A
2009-08-01
A quantum repeater is a system for long-distance quantum communication that employs quantum memory elements to mitigate optical fiber transmission losses. The multiplexed quantum memory (O. A. Collins, S. D. Jenkins, A. Kuzmich, and T. A. B. Kennedy, Phys. Rev. Lett. 98, 060502 (2007)) has been shown theoretically to reduce quantum memory time requirements. We present an initial implementation of a multiplexed quantum memory element in a cold rubidium gas. We show that it is possible to create atomic excitations in arbitrary memory element pairs and demonstrate the violation of Bell's inequality for light fields generated during the write and read processes.
Quantum capacity of quantum black holes
NASA Astrophysics Data System (ADS)
Adami, Chris; Bradler, Kamil
2014-03-01
The fate of quantum entanglement interacting with a black hole has been an enduring mystery, not the least because standard curved space field theory does not address the interaction of black holes with matter. We discuss an effective Hamiltonian of matter interacting with a black hole that has a precise analogue in quantum optics and correctly reproduces both spontaneous and stimulated Hawking radiation with grey-body factors. We calculate the quantum capacity of this channel in the limit of perfect absorption, as well as in the limit of a perfectly reflecting black hole (a white hole). We find that the white hole is an optimal quantum cloner, and is isomorphic to the Unruh channel with positive quantum capacity. The complementary channel (across the horizon) is entanglement-breaking with zero capacity, avoiding a violation of the quantum no-cloning theorem. The black hole channel on the contrary has vanishing capacity, while its complement has positive capacity instead. Thus, quantum states can be reconstructed faithfully behind the black hole horizon, but not outside. This work sheds new light on black hole complementarity because it shows that black holes can both reflect and absorb quantum states without violating the no-cloning theorem, and makes quantum firewalls obsolete.
Quantum optics. Gravity meets quantum physics
Adams, Bernhard W.
2015-02-27
Albert Einstein’s general theory of relativity is a classical formulation but a quantum mechanical description of gravitational forces is needed, not only to investigate the coupling of classical and quantum systems but simply to give a more complete description of our physical surroundings. In this issue of Nature Photonics, Wen-Te Liao and Sven Ahrens reveal a link between quantum and gravitational physics. They propose that in the quantum-optical effect of superradiance, the world line of electromagnetic radiation is changed by the presence of a gravitational field.
Work and quantum phase transitions: quantum latency.
Mascarenhas, E; Bragança, H; Dorner, R; França Santos, M; Vedral, V; Modi, K; Goold, J
2014-06-01
We study the physics of quantum phase transitions from the perspective of nonequilibrium thermodynamics. For first-order quantum phase transitions, we find that the average work done per quench in crossing the critical point is discontinuous. This leads us to introduce the quantum latent work in analogy with the classical latent heat of first order classical phase transitions. For second order quantum phase transitions the irreversible work is closely related to the fidelity susceptibility for weak sudden quenches of the system Hamiltonian. We demonstrate our ideas with numerical simulations of first, second, and infinite order phase transitions in various spin chain models.
Quantum Darwinism in Quantum Brownian Motion
NASA Astrophysics Data System (ADS)
Blume-Kohout, Robin; Zurek, Wojciech H.
2008-12-01
Quantum Darwinism—the redundant encoding of information about a decohering system in its environment—was proposed to reconcile the quantum nature of our Universe with apparent classicality. We report the first study of the dynamics of quantum Darwinism in a realistic model of decoherence, quantum Brownian motion. Prepared in a highly squeezed state—a macroscopic superposition—the system leaves records whose redundancy increases rapidly with initial delocalization. Redundancy appears rapidly (on the decoherence time scale) and persists for a long time.
Quantum Darwinism in quantum Brownian motion.
Blume-Kohout, Robin; Zurek, Wojciech H
2008-12-12
Quantum Darwinism--the redundant encoding of information about a decohering system in its environment--was proposed to reconcile the quantum nature of our Universe with apparent classicality. We report the first study of the dynamics of quantum Darwinism in a realistic model of decoherence, quantum Brownian motion. Prepared in a highly squeezed state--a macroscopic superposition--the system leaves records whose redundancy increases rapidly with initial delocalization. Redundancy appears rapidly (on the decoherence time scale) and persists for a long time.
Quantum Kolmogorov complexity and bounded quantum memory
Miyadera, Takayuki
2011-04-15
The effect of bounded quantum memory in a primitive information protocol has been examined using the quantum Kolmogorov complexity as a measure of information. We employed a toy two-party protocol in which Bob, by using a bounded quantum memory and an unbounded classical memory, estimates a message that was encoded in qubits by Alice in one of the bases X or Z. Our theorem gave a nontrivial effect of the memory boundedness. In addition, a generalization of the uncertainty principle in the presence of quantum memory has been obtained.
NASA Astrophysics Data System (ADS)
Shevkunov, S. V.
2016-08-01
A method for calculating the spin of the ground quantum state of nonrelativistic electrons and distance between energy levels of quantum states differing in the spin magnitude from first principles is proposed. The approach developed is free from the one-electron approximation and applicable in multielectron systems with allowance for all spatial correlations. The possibilities of the method are demonstrated by the example of calculating the energy gap between spin states in model ellipsoidal quantum dots with a harmonic confining field. The results of computations by the Monte Carlo method point to high sensitivity of the energy gap to the break of spherical symmetry of the quantum dot. For three electrons, the phenomenon of inversion has been revealed for levels corresponding to high and low values of the spin. The calculations demonstrate the practical possibility to obtain spin states with arbitrarily close energies by varying the shape of the quantum dot, which is a key condition for development prospects in technologies of storage systems based on spin qubits.
Converting Coherence to Quantum Correlations
NASA Astrophysics Data System (ADS)
Ma, Jiajun; Yadin, Benjamin; Girolami, Davide; Vedral, Vlatko; Gu, Mile
2016-04-01
Recent results in quantum information theory characterize quantum coherence in the context of resource theories. Here, we study the relation between quantum coherence and quantum discord, a kind of quantum correlation which appears even in nonentangled states. We prove that the creation of quantum discord with multipartite incoherent operations is bounded by the amount of quantum coherence consumed in its subsystems during the process. We show how the interplay between quantum coherence consumption and creation of quantum discord works in the preparation of multipartite quantum correlated states and in the model of deterministic quantum computation with one qubit.
Converting Coherence to Quantum Correlations.
Ma, Jiajun; Yadin, Benjamin; Girolami, Davide; Vedral, Vlatko; Gu, Mile
2016-04-22
Recent results in quantum information theory characterize quantum coherence in the context of resource theories. Here, we study the relation between quantum coherence and quantum discord, a kind of quantum correlation which appears even in nonentangled states. We prove that the creation of quantum discord with multipartite incoherent operations is bounded by the amount of quantum coherence consumed in its subsystems during the process. We show how the interplay between quantum coherence consumption and creation of quantum discord works in the preparation of multipartite quantum correlated states and in the model of deterministic quantum computation with one qubit.
Discretized Light-Cone Quantization: Application to Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Tang, Andrew Chun-Nien
. The numerical results shown are not competitive with state of the art calculations for positronium, but do demonstrate that the theoretical underpinnings of DLCQ are sound and that applications to other field theories such as Quantum Chromodynamics should be achievable. Further improvements in numerical technology may provide competitive answers.
Kendon, Vivien M; Nemoto, Kae; Munro, William J
2010-08-13
We briefly review what a quantum computer is, what it promises to do for us and why it is so hard to build one. Among the first applications anticipated to bear fruit is the quantum simulation of quantum systems. While most quantum computation is an extension of classical digital computation, quantum simulation differs fundamentally in how the data are encoded in the quantum computer. To perform a quantum simulation, the Hilbert space of the system to be simulated is mapped directly onto the Hilbert space of the (logical) qubits in the quantum computer. This type of direct correspondence is how data are encoded in a classical analogue computer. There is no binary encoding, and increasing precision becomes exponentially costly: an extra bit of precision doubles the size of the computer. This has important consequences for both the precision and error-correction requirements of quantum simulation, and significant open questions remain about its practicality. It also means that the quantum version of analogue computers, continuous-variable quantum computers, becomes an equally efficient architecture for quantum simulation. Lessons from past use of classical analogue computers can help us to build better quantum simulators in future.
Efficient Quantum Pseudorandomness
NASA Astrophysics Data System (ADS)
Brandão, Fernando G. S. L.; Harrow, Aram W.; Horodecki, Michał
2016-04-01
Randomness is both a useful way to model natural systems and a useful tool for engineered systems, e.g., in computation, communication, and control. Fully random transformations require exponential time for either classical or quantum systems, but in many cases pseudorandom operations can emulate certain properties of truly random ones. Indeed, in the classical realm there is by now a well-developed theory regarding such pseudorandom operations. However, the construction of such objects turns out to be much harder in the quantum case. Here, we show that random quantum unitary time evolutions ("circuits") are a powerful source of quantum pseudorandomness. This gives for the first time a polynomial-time construction of quantum unitary designs, which can replace fully random operations in most applications, and shows that generic quantum dynamics cannot be distinguished from truly random processes. We discuss applications of our result to quantum information science, cryptography, and understanding the self-equilibration of closed quantum dynamics.
NASA Astrophysics Data System (ADS)
Vanner, Michael R.; Pikovski, Igor; Cole, Garrett D.; Kim, Myungshik; Brukner, Caslav; Hammerer, Klemens; Milburn, Gerard J.; Aspelmeyer, Markus
2011-03-01
By combining quantum optics with mechanical resonators an avenue is opened to extend investigations of quantum behavior into unprecendented mass regimes. The field resulting from this combination - ``cavity quantum optomechanics'' -- is receiving a surge of interest for its potential to contribute to quantum measurement and control, studies of decoherence and non-classical state preparation of macroscopic objects. However, quantum state preparation and especially quantum state reconstruction of mechanical oscillators is currently a significant challenge. We are pursuing a scheme that employs short optical pulses to realize quantum state tomography, squeezing via measurement and state purifcation of a mechanical resonator. The pulsed scheme has considerable resilience to initial thermal occupation, provides a promising means to explore the quantum nature of massive oscillators and can be applied to other systems such as trapped ions. Our theoretical proposal and experimental results will be discussed.
Spring, William Joseph
2009-04-13
We consider quantum analogues of n-parameter stochastic processes, associated integrals and martingale properties extending classical results obtained in [1, 2, 3], and quantum results in [4, 5, 6, 7, 8, 9, 10].
Efficient Quantum Pseudorandomness.
Brandão, Fernando G S L; Harrow, Aram W; Horodecki, Michał
2016-04-29
Randomness is both a useful way to model natural systems and a useful tool for engineered systems, e.g., in computation, communication, and control. Fully random transformations require exponential time for either classical or quantum systems, but in many cases pseudorandom operations can emulate certain properties of truly random ones. Indeed, in the classical realm there is by now a well-developed theory regarding such pseudorandom operations. However, the construction of such objects turns out to be much harder in the quantum case. Here, we show that random quantum unitary time evolutions ("circuits") are a powerful source of quantum pseudorandomness. This gives for the first time a polynomial-time construction of quantum unitary designs, which can replace fully random operations in most applications, and shows that generic quantum dynamics cannot be distinguished from truly random processes. We discuss applications of our result to quantum information science, cryptography, and understanding the self-equilibration of closed quantum dynamics. PMID:27176509
NASA Astrophysics Data System (ADS)
Jennewein, Thomas; Higgins, Brendon
2013-03-01
Sending satellites equipped with quantum technologies into space will be the first step towards a global quantum-communication network. As Thomas Jennewein and Brendon Higgins explain, these systems will also enable physicists to test fundamental physics in new regimes.
Quantum information and computation
Bennett, C.H.
1995-10-01
A new quantum theory of communication and computation is emerging, in which the stuff transmitted or processed is not classical information, but arbitrary superpositions of quantum states. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.
Efficient Quantum Pseudorandomness.
Brandão, Fernando G S L; Harrow, Aram W; Horodecki, Michał
2016-04-29
Randomness is both a useful way to model natural systems and a useful tool for engineered systems, e.g., in computation, communication, and control. Fully random transformations require exponential time for either classical or quantum systems, but in many cases pseudorandom operations can emulate certain properties of truly random ones. Indeed, in the classical realm there is by now a well-developed theory regarding such pseudorandom operations. However, the construction of such objects turns out to be much harder in the quantum case. Here, we show that random quantum unitary time evolutions ("circuits") are a powerful source of quantum pseudorandomness. This gives for the first time a polynomial-time construction of quantum unitary designs, which can replace fully random operations in most applications, and shows that generic quantum dynamics cannot be distinguished from truly random processes. We discuss applications of our result to quantum information science, cryptography, and understanding the self-equilibration of closed quantum dynamics.
Quantum Spread Spectrum Communication
Humble, Travis S
2010-01-01
We demonstrate that spectral teleportation can coherently dilate the spectral probability amplitude of a single photon. In preserving the encoded quantum information, this variant of teleportation subsequently enables a form of quantum spread spectrum communication.
NASA Astrophysics Data System (ADS)
Goyal, Ketan; Kawai, Ryoichi
As nanotechnology advances, understanding of the thermodynamic properties of small systems becomes increasingly important. Such systems are found throughout physics, biology, and chemistry manifesting striking properties that are a direct result of their small dimensions where fluctuations become predominant. The standard theory of thermodynamics for macroscopic systems is powerless for such ever fluctuating systems. Furthermore, as small systems are inherently quantum mechanical, influence of quantum effects such as discreteness and quantum entanglement on their thermodynamic properties is of great interest. In particular, the quantum fluctuations due to quantum uncertainty principles may play a significant role. In this talk, we investigate thermodynamic properties of an autonomous quantum heat engine, resembling a quantum version of the Feynman Ratchet, in non-equilibrium condition based on the theory of open quantum systems. The heat engine consists of multiple subsystems individually contacted to different thermal environments.
Quantum dots as active material for quantum cascade lasers: comparison to quantum wells
NASA Astrophysics Data System (ADS)
Michael, Stephan; Chow, Weng W.; Schneider, Hans Christian
2016-03-01
We review a microscopic laser theory for quantum dots as active material for quantum cascade lasers, in which carrier collisions are treated at the level of quantum kinetic equations. The computed characteristics of such a quantum-dot active material are compared to a state-of-the-art quantum-well quantum cascade laser. We find that the current requirement to achieve a comparable gain-length product is reduced compared to that of the quantum-well quantum cascade laser.
NASA Astrophysics Data System (ADS)
Bengtsson, Ingemar; Zyczkowski, Karol
2007-12-01
Preface; 1. Convexity, colours and statistics; 2. Geometry of probability distributions; 3. Much ado about spheres; 4. Complex projective spaces; 5. Outline of quantum mechanics; 6. Coherent states and group actions; 7. The stellar representation; 8. The space of density matrices; 9. Purification of mixed quantum states; 10. Quantum operations; 11. Duality: maps versus states; 12. Density matrices and entropies; 13. Distinguishability measures; 14. Monotone metrics and measures; 15. Quantum entanglement; Epilogue; Appendices; References; Index.
Huang, Liang; Lai Yingcheng; Ferry, David K.; Goodnick, Stephen M.; Akis, Richard
2009-07-31
The concentrations of wave functions about classical periodic orbits, or quantum scars, are a fundamental phenomenon in physics. An open question is whether scarring can occur in relativistic quantum systems. To address this question, we investigate confinements made of graphene whose classical dynamics are chaotic and find unequivocal evidence of relativistic quantum scars. The scarred states can lead to strong conductance fluctuations in the corresponding open quantum dots via the mechanism of resonant transmission.
Introduction to Quantum Computation
NASA Astrophysics Data System (ADS)
Ekert, A.
A computation is a physical process. It may be performed by a piece of electronics or on an abacus, or in your brain, but it is a process that takes place in nature and as such it is subject to the laws of physics. Quantum computers are machines that rely on characteristically quantum phenomena, such as quantum interference and quantum entanglement in order to perform computation. In this series of lectures I want to elaborate on the computational power of such machines.
Quantum computing and probability.
Ferry, David K
2009-11-25
Over the past two decades, quantum computing has become a popular and promising approach to trying to solve computationally difficult problems. Missing in many descriptions of quantum computing is just how probability enters into the process. Here, we discuss some simple examples of how uncertainty and probability enter, and how this and the ideas of quantum computing challenge our interpretations of quantum mechanics. It is found that this uncertainty can lead to intrinsic decoherence, and this raises challenges for error correction.
Is quantum probability rational?
Houston, Alasdair I; Wiesner, Karoline
2013-06-01
We concentrate on two aspects of the article by Pothos & Busemeyer (P&B): the relationship between classical and quantum probability and quantum probability as a basis for rational decisions. We argue that the mathematical relationship between classical and quantum probability is not quite what the authors claim. Furthermore, it might be premature to regard quantum probability as the best practical rational scheme for decision making.
NASA Astrophysics Data System (ADS)
Salih, Hatim
2016-05-01
The phenomenon of quantum erasure has long intrigued physicists, but has surprisingly found limited practical application. Here, we propose a protocol for quantum key distribution (QKD) based on quantum erasure, promising inherent security against detector attacks. We particularly demonstrate its security against a powerful detector-blinding attack.
Eavesdropping without quantum memory
Bechmann-Pasquinucci, H.
2006-04-15
In quantum cryptography the optimal eavesdropping strategy requires that the eavesdropper uses ancillas and quantum memories in order to optimize her information. What happens if the eavesdropper has no quantum memory? It is shown that in this case the eavesdropper obtains a better information/disturbance trade-off by adopting the simple intercept/resend strategy.
Quantum phenomena in superconductors
Clarke, J.
1987-08-01
This paper contains remarks by the author on aspects of macroscopic quantum phenomena in superconductors. Some topics discussed are: Superconducting low-inductance undulatory galvanometer (SLUGS), charge imbalance, cylindrical dc superconducting quantum interference device (SQUIDS), Geophysics, noise theory, magnetic resonance with SQUIDS, and macroscopic quantum tunneling. 23 refs., 4 figs. (LSP)
NASA Astrophysics Data System (ADS)
Iqbal, A.; Toor, A. H.
2002-03-01
We investigate the role of quantum mechanical effects in the central stability concept of evolutionary game theory, i.e., an evolutionarily stable strategy (ESS). Using two and three-player symmetric quantum games we show how the presence of quantum phenomenon of entanglement can be crucial to decide the course of evolutionary dynamics in a population of interacting individuals.
Mesoscopic cavity quantum electrodynamics with quantum dots
Childress, L.; Soerensen, A.S.; Lukin, M.D.
2004-04-01
We describe an electrodynamic mechanism for coherent, quantum-mechanical coupling between spatially separated quantum dots on a microchip. The technique is based on capacitive interactions between the electron charge and a superconducting transmission line resonator, and is closely related to atomic cavity quantum electrodynamics. We investigate several potential applications of this technique which have varying degrees of complexity. In particular, we demonstrate that this mechanism allows design and investigation of an on-chip double-dot microscopic maser. Moreover, the interaction may be extended to couple spatially separated electron-spin states while only virtually populating fast-decaying superpositions of charge states. This represents an effective, controllable long-range interaction, which may facilitate implementation of quantum information processing with electron-spin qubits and potentially allow coupling to other quantum systems such as atomic or superconducting qubits.
Quantum computing. Defining and detecting quantum speedup.
Rønnow, Troels F; Wang, Zhihui; Job, Joshua; Boixo, Sergio; Isakov, Sergei V; Wecker, David; Martinis, John M; Lidar, Daniel A; Troyer, Matthias
2014-07-25
The development of small-scale quantum devices raises the question of how to fairly assess and detect quantum speedup. Here, we show how to define and measure quantum speedup and how to avoid pitfalls that might mask or fake such a speedup. We illustrate our discussion with data from tests run on a D-Wave Two device with up to 503 qubits. By using random spin glass instances as a benchmark, we found no evidence of quantum speedup when the entire data set is considered and obtained inconclusive results when comparing subsets of instances on an instance-by-instance basis. Our results do not rule out the possibility of speedup for other classes of problems and illustrate the subtle nature of the quantum speedup question.
NASA Astrophysics Data System (ADS)
Adler, Stephen L.; Bassi, Angelo; Dowker, Fay; Dürr, Detlef
2007-03-01
This special issue of Journal of Physics A: Mathematical and Theoretical entitled 'The Quantum Universe' is dedicated to Professor Giancarlo Ghirardi on the occasion of his 70th birthday. Giancarlo Ghirardi has made many important contributions to the foundations of quantum mechanics including the celebrated Ghirardi Rimini Weber (GRW) model of spontaneous wavefunction collapse. However, although Professor Ghirardi's birthday is the inspiration for this issue, it has a much broader scope than the area traditionally known as Foundations of Quantum Mechanics. All invited authors are experts in areas of physics in which quantum theory is fundamental: non relativistic quantum mechanics, quantum computation and information, quantum field theory, quantum gravity, quantum cosmology and philosophy of science. The issue was conceived as an opportunity for workers in these diverse areas to share with the widest possible readership their views on quantum theory. Authors were encouraged to give their personal assessment of the role of quantum theory in their work particularly as it pertains to a vision of the global aims of their research. The articles are accessible to any physicist with a solid knowledge of quantum mechanics, and many contain an emphasis on conceptual developments, both those achieved and those hoped for. One theme that runs throughout Giancarlo Ghirardi's contributions to science is the unity of physics: the development of the GRW model itself was motivated by the conviction that the same physics should govern microscopic and macroscopic systems. However, readers of this special issue will clearly see that there is no unity as yet in the views of workers on fundamental quantum theories. Indeed the diversity of the articles, ranging from technical developments in well defined approaches, to new proposals for interpretations of quantum mechanics, indicates the state of fundamental physics: healthily active and yet lacking the consensus we seek in science
Relativistic nuclear many-body theory
Serot, B.D. ); Walecka, J.D. . Continuous Electron Beam Accelerator Facility)
1991-09-11
Nonrelativistic models of nuclear systems have provided important insight into nuclear physics. In future experiments, nuclear systems will be examined under extreme conditions of density and temperature, and their response will be probed at momentum and energy transfers larger than the nucleon mass. It is therefore essential to develop reliable models that go beyond the traditional nonrelativistic many-body framework. General properties of physics, such as quantum mechanics, Lorentz covariance, and microscopic causality, motivate the use of quantum field theories to describe the interacting, relativistic, nuclear many-body system. Renormalizable models based on hadronic degrees of freedom (quantum hadrodynamics) are presented, and the assumptions underlying this framework are discussed. Some applications and successes of quantum hadrodynamics are described, with an emphasis on the new features arising from relativity. Examples include the nuclear equation of state, the shell model, nucleon-nucleus scattering, and the inclusion of zero-point vacuum corrections. Current issues and problems are also considered, such as the construction of improved approximations, the full role of the quantum vacuum, and the relationship between quantum hadrodynamics and quantum chromodynamics. We also speculate on future developments. 103 refs., 18 figs.
Quantum Tomograms and Their Application in Quantum Information Science
NASA Astrophysics Data System (ADS)
Fedorov, Aleksey K.; Yurchenko, Stanislav O.
2013-02-01
This note is devoted to quantum tomograms application in quantum information science. Representation for quantum tomograms of continuous variables via Feynman path integrals is considered. Due to this construction quantum tomograms of harmonic oscillator are obtained. Application tomograms in causal analysis of quantum states is presented. Two qubit maximum entangled and "quantum-classical" states have been analyzed by tomographic causal analysis of quantum states.
BOOK REVIEWS: Quantum Mechanics: Fundamentals
NASA Astrophysics Data System (ADS)
Whitaker, A.
2004-02-01
. It has a restricted range of general topics, and consists of three parts entitled `Nonrelativistic Many-Particle Systems', `Relativistic Wave Equations', and `Relativistic Fields'. Thus it studies in some depth areas of physics which are either dealt with in an introductory fashion, or not reached at all, by Gottfried and Yan. Despite its more advanced level, this book may actually be the more accessible to an isolated learner, because the various aspects are developed in an unhurried fashion; the author remarks that ‘the inclusion of all mathematical steps and full presentation of intermediate calculations ensures ease of understanding’. Many useful student problems are included. The presentation is said to be rigorous, but again this is a book for the physicist rather than the mathematician. The treatment of many-particle systems begins with a rather general introduction to second quantization, and then applies this formalism to spin-1/2 fermions and bosons. The study of fermions includes consideration of the Fermi sphere, the electron gas, and the Hartree--Fock equations for atoms; that of bosons includes Bose--Einstein condensation, Bogoliubov theory of the weakly interacting Bose gas, and a brief account of superfluidity. The last section of this part of the book investigates in detail the dynamics of many-particle systems on a microscopic quantum-mechanical basis using, in particular, the dynamical correlation functions. In the second part which considers relativistic wave equations, the Klein--Gordon and Dirac equations are derived, and the Lorentz covariance of the Dirac equation is established. The role of angular momentum in relativistic quantum mechanics is explained, as a preliminary to the study of the energy levels in a Coulomb potential using both the Klein--Gordon and Dirac equations, the latter being solved exactly for the hydrogen atom. For larger atoms, the Foldy--Wouthuysen transformation is explained, and also relativistic corrections and the
NASA Astrophysics Data System (ADS)
Tulsi, Avatar
2016-07-01
Quantum spatial search has been widely studied with most of the study focusing on quantum walk algorithms. We show that quantum walk algorithms are extremely sensitive to systematic errors. We present a recursive algorithm which offers significant robustness to certain systematic errors. To search N items, our recursive algorithm can tolerate errors of size O(1{/}√{ln N}) which is exponentially better than quantum walk algorithms for which tolerable error size is only O(ln N{/}√{N}). Also, our algorithm does not need any ancilla qubit. Thus our algorithm is much easier to implement experimentally compared to quantum walk algorithms.
Scalable optical quantum computer
Manykin, E A; Mel'nichenko, E V
2014-12-31
A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr{sup 3+}, regularly located in the lattice of the orthosilicate (Y{sub 2}SiO{sub 5}) crystal, are suggested to be used as optical qubits. Operations with qubits are performed using coherent and incoherent laser pulses. The operation protocol includes both the method of measurement-based quantum computations and the technique of optical computations. Modern hybrid photon echo protocols, which provide a sufficient quantum efficiency when reading recorded states, are considered as most promising for quantum computations and communications. (quantum computer)
Quantum Operation Time Reversal
Crooks, Gavin E.
2008-03-25
The dynamics of an open quantum system can be described by a quantum operation: A linear, complete positive map of operators. Here, I exhibit a compact expression for the time reversal of a quantum operation, which is closely analogous to the time reversal of a classical Markov transition matrix. Since open quantum dynamics are stochastic, and not, in general, deterministic, the time reversal is not, in general, an inversion of the dynamics. Rather, the system relaxes toward equilibrium in both the forward and reverse time directions. The probability of a quantum trajectory and the conjugate, time reversed trajectory are related by the heat exchanged with the environment.
Complementarity and quantum walks
Kendon, Viv; Sanders, Barry C.
2005-02-01
We show that quantum walks interpolate between a coherent 'wave walk' and a random walk depending on how strongly the walker's coin state is measured; i.e., the quantum walk exhibits the quintessentially quantum property of complementarity, which is manifested as a tradeoff between knowledge of which path the walker takes vs the sharpness of the interference pattern. A physical implementation of a quantum walk (the quantum quincunx) should thus have an identifiable walker and the capacity to demonstrate the interpolation between wave walk and random walk depending on the strength of measurement.
Duality quantum computer and the efficient quantum simulations
NASA Astrophysics Data System (ADS)
Wei, Shi-Jie; Long, Gui-Lu
2016-03-01
Duality quantum computing is a new mode of a quantum computer to simulate a moving quantum computer passing through a multi-slit. It exploits the particle wave duality property for computing. A quantum computer with n qubits and a qudit simulates a moving quantum computer with n qubits passing through a d-slit. Duality quantum computing can realize an arbitrary sum of unitaries and therefore a general quantum operator, which is called a generalized quantum gate. All linear bounded operators can be realized by the generalized quantum gates, and unitary operators are just the extreme points of the set of generalized quantum gates. Duality quantum computing provides flexibility and a clear physical picture in designing quantum algorithms, and serves as a powerful bridge between quantum and classical algorithms. In this paper, after a brief review of the theory of duality quantum computing, we will concentrate on the applications of duality quantum computing in simulations of Hamiltonian systems. We will show that duality quantum computing can efficiently simulate quantum systems by providing descriptions of the recent efficient quantum simulation algorithm of Childs and Wiebe (Quantum Inf Comput 12(11-12):901-924, 2012) for the fast simulation of quantum systems with a sparse Hamiltonian, and the quantum simulation algorithm by Berry et al. (Phys Rev Lett 114:090502, 2015), which provides exponential improvement in precision for simulating systems with a sparse Hamiltonian.