bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scopes and limits of modality in quantum mechanics
Authors: Domenech G. , Freytes H. , de Ronde C. 
Published: June 2022

AbstractWe develop an algebraic frame for the simultaneous treatment of actual and possible properties of quantum systems. We show that, in spite of the fact that the language is enriched with the addition of a modal operator to the orthomodular structure, contextuality remains a central feature of quantum systems.
The gravitomagnetic clock effect and its possible observation
Authors: Lichtenegger H. , Iorio L. , Mashhoon B. 
Published: June 2022

AbstractThe general relativistic gravitomagnetic clock effect involves a coupling between the orbital motion of a test particle and the rotation of the central mass and results in a difference in the proper periods of two counter–revolving satellites. It is shown that at 𝒪(c‐2) this effect has a simple analogue in the electromagnetic case. Moreover, in view of a possible measurement of the clock effect in the gravitational field of the Earth, we investigate the influence of some classical perturbing forces of the terrestrial space environment on the orbital motion of test bodies along opposite trajectories.
Equations of motion for a (non‐linear) scalar field model as derived from the field equations
Authors: Kaniel S. , Itin Y. 
Published: June 2022

AbstractThe problem of derivation of the equations of motion from the field equations is considered. Einstein's field equations have a specific analytical form: They are linear in the second order derivatives and quadratic in the first order derivatives of the field variables. We utilize this particular form and propose a novel algorithm for the derivation of the equations of motion from the field equations. It is based on the condition of the balance between the singular terms of the field equation. We apply the algorithm to a non‐linear Lorentz invariant scalar field model. We show that it results in the Newton law of attraction between the singularities of the field moved on approximately geodesic curves. The algorithm is applicable to the N‐body problem of the Lorentz invariant field equations.
The self‐energy of the uniform electron gas in the second order of exchange
Authors: Ziesche P. 
Published: June 2022

AbstractThe on‐shell self‐energy of the homogeneous electron gas in second order of exchange, Σ2x = Re Σ2x (kF, k2 F/2), is given by a certain integral. This integral is treated here in a similar way as Onsager, Mittag, and Stephen [Ann. Physik (Leipzig) 18, 71 (1966)] have obtained their famous analytical expression e2x = (in atomic units) for the correlation energy in second order of exchange. Here it is shown that the result for the corresponding on‐shell self‐energy is Σ2x = e2x. The off‐shell self‐energy Σ2x (k, o) correctly yields 2e2x (the potential component of e2x) through the Galitskii‐Migdal formula. The quantities e2x and Σ2x appear in the high‐density limit of the Hugenholtz‐van Hove (Luttinger‐Ward) theorem.
Toward a nonlocal theory of gravitation
Authors: Mashhoon B. 
Published: June 2022

AbstractThe nonlocal theory of accelerated systems is extended to linear gravitational waves as measured by accelerated observers in Minkowski spacetime. The implications of this approach are discussed. In particular, the nonlocal modifications of helicity‐rotation coupling are pointed out and a nonlocal wave equation is presented for a special class of uniformly rotating observers. The results of this study, via Einstein's heuristic principle of equivalence, provide the incentive for a nonlocal classical theory of the gravitational field.
From RHIC to LHC: a relativistic diffusion approach
Authors: Kuiper R. , Wolschin G. 
Published: June 2022

AbstractWe investigate the energy dependence of stopping and hadron production in high‐energy heavy‐ion collisions based on a three‐sources Relativistic Diffusion Model. The transport coefficients are extrapolated from Au + Au and Cu + Cu at RHIC energies ( = 19.6–200 GeV) to Pb + Pb at LHC energies = 5.52 TeV. Rapidity distributions for net protons, and pseudorapidity spectra for produced charged particles in central collisions are compared to data at RHIC energies, and discussed for several extrapolations to LHC energies.
Introducing relativity in global navigation satellite systems
Authors: Pascual‐Sánchez J.‐F. 
Published: June 2022

AbstractToday, the Global Navigation Satellite Systems, used as global positioning systems, are the GPS and the GLONASS. They are based on a Newtonian model and hence they are only operative when several relativistic effects are taken into account. The most important relativistic effects (to order 1/c2) are: the Einstein gravitational blue shift effect of the satellite clock frequency (Equivalence Principle of General Relativity) and the Doppler red shift of second order, due to the motion of the satellite (Special Relativity). On the other hand, in a few years the Galileo system will be built, copying the GPS system unless an alternative project is designed. In this work, it will be also shown that the SYPOR project, using fully relativistic concepts, is an alternative to a mere copy of the GPS system. According to this project, the Galileo system would be exact and there would be no need for relativistic corrections.
The Einstein‐Elko system – Can dark matter drive inflation?
Authors: Böhmer C.G. 
Published: June 2022

AbstractRecently, a spin one half matter field with mass dimension one was discovered, called Elko spinors. The present work shows how to introduce these fields into a curved spacetime by the standard covariantisation scheme. After formulating the coupled Einstein‐Elko field equations, the spacetime is assumed to be homogeneous and isotropic in order to simplify the resulting field equations. Analytical ghost Elko solutions are constructed which have vanishing energy‐momentum tensor without and with cosmological constant. The cosmological Elko theory is finally related to the standard scalar field theory with self interaction that gives rise to inflation and it is pointed out that the Elko spinors are not only prime dark matter candidates but also prime candidates for inflation.
Berry phase of two atoms in the same quantized light field
Authors: Liang M.‐L. , Zhang J.‐H. , Yuan B. 
Published: June 2022

AbstractThe Berry phase of two atoms exposed to the same quantized light field has been studied. The interaction between each atom and the light field obeys the Jaynes‐Cummings model. Due to the quantization of the light field, the interaction Hamiltonians for the two atoms interacting with the field do not commute with each other, which induces new parts in the Berry phase. Meanwhile, there appears a phase which doesn't exist in the classical regime and is purely induced by the field quantization.
Synergetic analysis of the Häussler‐von der Malsburg equations for manifolds of arbitrary geometry
Authors: Güßmann M. , Pelster A. , Wunner G. 
Published: June 2022

AbstractWe generalize a model of Häussler and von der Malsburg which describes the self‐organized generation of retinotopic projections between two one‐dimensional discrete cell arrays on the basis of cooperative and competitive interactions of the individual synaptic contacts. Our generalized model is independent of the special geometry of the cell arrays and describes the temporal evolution of the connection weights between cells on different manifolds. By linearizing the equations of evolution around the stationary uniform state we determine the critical global growth rate for synapses onto the tectum where an instability arises. Within a nonlinear analysis we use then the methods of synergetics to adiabatically eliminate the stable modes near the instability. The resulting order parameter equations describe the emergence of retinotopic projections from initially undifferentiated mappings independent of dimension and geometry.
A new look at the quantum mechanics of the harmonic oscillator
Authors: Kastrup H.A. 
Published: June 2022

AbstractIn classical mechanics the harmonic oscillator (HO) provides the generic example for the use of angle and action variables and I > 0 which played a prominent role in the “old” Bohr‐Sommerfeld quantum theory. However, already classically there is a problem which has essential implications for the quantum mechanics of the (φ,I)‐model for the HO: the transformation is only locally symplectic and singular for (q,p) = (0,0). Globally the phase space {(q,p)} has the topological structure of the plane ℝ2, whereas the phase space {(φ,I)} corresponds globally to the punctured plane ℝ2 ‐(0,0) or to a simple cone with the tip deleted. From the properties of the symplectic transformations on that phase space one can derive the functions h0 = I, h1 = Icos φ and h2 = ‐Isin φ as the basic coordinates on {(φ,I)}, where their Poisson brackets obey the Lie algebra of the symplectic group of the plane. This implies a qualitative difference as to the quantum theory of the phase space {(φ,I)} compared to the usual one for {(q,p)}: In the quantum mechanics for the (φ,I)‐model of the HO the three hj correspond to the self‐adjoint generators Kj, j = 0,1,2, of certain irreducible unitary representations of the symplectic group or one of its infinitely many covering groups, the representations being parametrized by a (Bargmann) index k > 0. This index k determines the ground state energy of the (φ,I)‐Hamiltonian . For an m‐fold covering the lowest possible value for k is k = 1/m, which can be made arbitrarily small by choosing m accordingly! This is not in contradiction to the usual approach in terms of the operators Q and P which are now expressed as functions of the Kj, but keep their usual properties. The richer structure of the Kj quantum model of the HO is “erased” when passing to the simpler (Q,P)‐model! This more refined approach to the quantum theory of the HO implies many experimental tests: Mulliken‐type experiments for isotopic diatomic molecules, experiments with harmonic traps for atoms, ions and BE‐condensates, with charged HOs in external electric fields and the (Landau) levels of charged particles in external magnetic fields, with the propagation of light in vacuum, passing through strong external electric or magnetic fields. Finally it may lead to a new theoretical estimate for the quantum vacuum energy of fields and its relation to the cosmological constant.
The radial wavefunction of a relativistic binary of two fermions bound by the Coulomb force
Authors: Marsch E. 
Published: June 2022

AbstractThe exact radial eigenfunctions of a relativistic binary atom bound by the static Coulomb force are calculated. We consider the two‐fermion Dirac equation for two distinguishable fermions (like, e.g., in positronium) including the static Coulomb potential but no radiative corrections. As shown in a previous paper and its addendum this problem can be solved exactly [1]. Here we provide the exact solution in terms of generalized hypergeometric functions for the radial eigenfunctions of the hamiltonian, which are determined through a matrix recursion relation. Also, an equivalent set of coupled first‐order, or uncoupled second‐order, differential equations that may be solved numerically is provided.
A case study of the Hirsch index for 26 non‐prominent physicists
Authors: Schreiber M. 
Published: June 2022

AbstractThehindex was introduced by Hirsch to quantify an individual's scientific research output. It has been widely used in different fields to show the relevance of the research work of prominent scientists. I have worked out 26 practical cases of physicists which are not so prominent. Therefore this case study should be more relevant to discuss various features of the Hirsch index which are interesting or disturbing or both for the more average situation. In particular, I investigate quantitatively some pitfalls in the evaluation and the influence of self‐citations.
Statistics of charge transfer through impurities in strongly correlated 1D metals*
Authors: Komnik A. , Trauzettel B. , Weiss U. 
Published: June 2022

AbstractWe review recent advances in the field of full counting statistics (FCS) of charge transfer through impurities imbedded into strongly correlated one‐dimensional metallic systems, modelled by Tomonaga‐Luttinger liquids (TLLs). We concentrate on the exact analytic solutions for the cumulant generating function, which became available recently and apply these methods in order to obtain the FCS of a non‐trivial contact between two crossed TLL.
Shot noise in non‐adiabatically driven nanoscale conductors*
Authors: Kaiser F.J. , Kohler S. 
Published: June 2022

AbstractWe investigate the noise properties of pump currents through molecular wires and coupled quantum dots. As a model we employ a two‐level system that is connected to electron reservoirs and is non‐adiabatically driven. Concerning the electron‐electron interaction, we focus on two limits: non‐interacting electrons and strong Coulomb repulsion. While the former case is treated within a Floquet scattering formalism, we derive for the latter case a master equation formalism for the computation of the current and the zero‐frequency noise. For a pump operated close to internal resonances, the differences between the non‐interacting and the strongly interacting limit turn out to be surprisingly small.
It's the coupling that creates resistance: Spin electronics in layered magnetic structures
Authors: Grünberg P. 
Published: June 2022

AbstractFast‐paced technological advancement is squeezing the data on computer hard disks ever closer together. For some ten years now, continuously shrinking and increasingly sensitive read/write heads are making use of the giant magnetoresistance (GMR) effect discovered in 1988. This term was coined for the effect that electric resistance of a magnetic layer system changes dramatically when the magnetization of the individual layers is reversed from antiparallel to parallel orientation. Very small external magnetic fields suffice to change the orientation and thus give GMR read/write heads their high sensitivity.
Max Planck – a life for thermodynamics*
Authors: Müller I. 
Published: June 2022

AbstractEvery problem that Max Planck approached during his long and distinguished career turned out, one way or another, to be motivated by thermodynamics and considerations of entropy. This was so, in particular, when Planck formulated the correct formula for the spectrum of black‐body radiation, whose interpretation made him the earliest pioneer of quantum mechanics. With his formulation of the third law of thermodynamics he gave the entropy a specific and definite value, which – to his own surprise – was closely related to the action quantum h, which we now call Planck's constant.
On the nature of thermodynamic extremum principles: The case of maximum efficiency and maximum work*
Authors: Jahnke T. , Birjukov J. , Mahler G. 
Published: June 2022

AbstractExtremum principles are at the heart of theoretical physics. For a complete definition one does not only need to specify the variable to be extremized but also the respective functional space and its parametrization. Here we use a control‐theoretical approach to clarify the meaning of two maximum principles in the context of cyclic thermodynamic processes.
The Fokker‐Planck equation, and its application in plasma physics*
Authors: Peeters A.G. , Strintzi D. 
Published: June 2022

AbstractIn a classic paper Max Planck derived an equation, now known as the Fokker‐Planck equation, which plays a central role in the statistics description of many body problems. The equation is used in many branches of physics as well as chemistry and biology to describe a variety of different processes. In plasma physics, on which this paper concentrates, it forms the corner stone for the description of the Coulomb collisions. Furthermore, it is pointed out that also the so‐called quasi‐linear theory is closely related to the Fokker‐Planck equation.
Influence of light waves on the thermoelectric power under large magnetic field in III‐V, ternary and quaternary materials
Authors: Ghatak K.P. , Bhattacharya S. , Pahari S. , De D. , Ghosh S. , Mitra M. 
Published: June 2022

AbstractWe study theoretically the influence of light waves on the thermoelectric power under large magnetic field (TPM) for III‐V, ternary and quaternary materials, whose unperturbed energy‐band structures, are defined by the three‐band model of Kane. The solution of the Boltzmann transport equation on the basis of this newly formulated electron dispersion law will introduce new physical ideas and experimental findings in the presence of external photoexcitation. It has been found by taking n‐InAs, n‐InSb, n‐Hg1‐xCdxTe and n‐In1‐xGaxAsyP1‐y lattice matched to InP as examples that the TPM decreases with increase in electron concentration, and increases with increase in intensity and wavelength, respectively in various manners. The strong dependence of the TPM on both light intensity and wavelength reflects the direct signature of light waves that is in direct contrast as compared with the corresponding bulk specimens of the said materials in the absence of external photoexcitation. The rate of change is totally band‐structure dependent and is significantly influenced by the presence of the different energy‐band constants. The well‐known result for the TPM for nondegenerate wide‐gap materials in the absence of light waves has been obtained as a special case of the present analysis under certain limiting conditions and this compatibility is the indirect test of our generalized formalism. Besides, we have also suggested the experimental methods of determining the Einstein relation for the diffusivity:mobility ratio, the Debye screening length and the electronic contribution to the elastic constants for materials having arbitrary dispersion laws.
Superluminal propagation of evanescent modes as a quantum effect
Authors: Wang Z.‐Y. , Xion C.‐D. , He B. 
Published: June 2022

AbstractContrary to mechanical waves, the two‐slit interference experiment of single photons shows that the behavior of classical electromagnetic waves corresponds to the quantum mechanical one of single photons, which is also different from the quantum‐field‐theory behavior such as the creations and annihilations of photons, the vacuum fluctuations, etc. Owing to a purely quantum effect, quantum tunneling particles including tunneling photons (evanescent modes) can propagate over a spacelike interval. With this picture we conclude that the superluminality of evanescent modes is a quantum mechanical rather than a classical phenomenon.
Effect of pure phase decoherence on entanglement teleportation
Authors: Ge M. , Zhu L.‐F. , Qiu Liang 
Published: June 2022

AbstractWe study entanglement teleportation in the two‐qubit XX Heisenberg model with pure phase decoherence taken into account. For some initial entangled states, pure phase decoherence has no effect on the teleported entanglement, while for others pure phase decoherence has a pronounced effect. In addition, entanglement sudden death happens in the latter case.
Universal tunneling time for all fields
Authors: Nimtz G. , Stahlhofen A.A. 
Published: June 2022

AbstractTunneling is an outstanding physical process. The observation that particles surmount a high barrier in spite of the fact that they don't have the necessary energy can not be explained by classical physics. However, this so called tunneling became allowed by quantum mechanics. Experimental tunneling studies with different photonic barriers from microwave frequencies up to ultraviolet frequencies point towards a universal tunneling time [1, 2]. Tunneling can be described by virtual, that is, by unobservable particles [3]. In the case of tunneling there is a virtual particle between the real incident and the real transmitted particles. Tunneling modes are solutions of the Schrödinger and of the Helmholtz equations. The most prominent example of the occurrence of tunneling modes in optics is frustrated total internal reflection (FTIR) at double prisms. In 1949 Sommerfeld [4] pointed out that this optical phenomenon represents the analogy of quantum mechanical particle tunneling. Recent experimental and theoretical data confirmed the conjecture that the tunneling process is characterized by a universal tunneling time presumably independent of the kind of field. The observed tunneling processes proceeded at a time of the order of magnitude of the reciprocal frequency of the wave packets.
Revival‐collapse phenomenon in the quadrature squeezing of the multiphoton Jaynes‐Cummings model with the binomial states
Authors: El‐Orany F.A.A. 
Published: June 2022

AbstractIn this paper we study the interaction between a two‐level atom and a quantized single‐mode field, namely, the Jaynes‐Cummings model (JCM). The field and the atom are initially prepared in the binomial state and the excited atomic state, respectively. For this system we prove that the revival‐collapse phenomenon exhibited in the atomic inversion of the standard JCM can be numerically (naturally) manifested in the evolution of the squeezing factor of the three‐photon (standard) JCM provided that the initial photon‐number distribution of the radiation field has a smooth envelope.
Four‐level systems and a universal quantum gate
Authors: Baldiotti M.C. , Gitman D.M. 
Published: June 2022

AbstractWe discuss the possibility of implementing a universal quantum XOR gate by using two coupled quantum dots subject to external magnetic fields that are parallel and slightly different. We consider this system in two different field configurations. In the first case, parallel external fields with the intensity difference at each spin being proportional to the time‐dependent interaction between the spins. A general exact solution describing this system is presented and analyzed to adjust field parameters. Then we consider parallel fields with intensity difference at each spin being constant and the interaction between the spins switching on and off adiabatically. In both cases we adjust characteristics of the external fields (their intensities and duration) in order to have the parallel pulse adequate for constructing the XOR gate. In order to provide a complete theoretical description of all the cases, we derive relations between the spin interaction, the inter‐dot distance, and the external field.
Particle production and nonlinear diffusion in relativistic systems
Authors: Wolschin G. 
Published: June 2022

AbstractThe short parton production phase in high‐energy heavy‐ion collisions is treated analytically as a nonlinear diffusion process. The initial buildup of the rapidity density distributions of produced charged hadrons within τp≃ 0.25 fm/c occurs in three sources during the colored partonic phase. In a two‐step approach, the subsequent diffusion in pseudorapidity space during the interaction time of τint≃ 7‐10 fm/c (mean duration of the collision) is essentially linear as expressed in the Relativistic Diffusion Model (RDM) which yields excellent agreement with the data at RHIC energies, and allows for predictions at LHC energies. Results for d+Au are discussed in detail.
Max Born and his legacy to condensed matter physics*
Authors: Cardona M. , Marx W. 
Published: June 2022

AbstractAfter a presentation of Max Born's most salient biographical data, we discuss his contributions to science and science policy, with special emphasis on those related to condensed matter physics. Our discussion includes journal articles as well as books. The methodology used is both qualitative and quantitative, including number of items, number of formal and informal citations, and other bibliometric indicators such as the recently proposed Hirsch index (h‐index). The data are mainly based on the Thomson/ISI Web of Science (WoS) which covers a carefully selected set of the more prestigious journals dating back to 1900. Born's books and articles not published in the journals covered by the WoS can also be evaluated, provided they are cited within the WoS journals. Some anecdotic and historical details, which have come to the fore in the course of our bibliometric investigations, are included.