Showing papers on "Quantum published in 1976"
280 citations
TL;DR: Theoretical aspects of the interaction of atoms with the radiation field are reviewed with emphasis on those features of the interactions requiring field quantization as mentioned in this paper, with special attention given to the theory of spontaneous emission.
228 citations
TL;DR: In this article, a description of quantum dynamical semigroups under detailed balance condition is given, and the onsager relations not far from the stationary state are obtained, and a special class of such semiigroups is studied in detail.
193 citations
TL;DR: An elementary procedure for calculating quantum mechanically the time-dependent rotation-vibration wave function for a collisionless model of a polyatomic molecule in a monochromatic radiation field is described and applied to some very simple cases as discussed by the authors.
144 citations
TL;DR: In this paper, the power spectra of Cerenkov, synchrotron, and synchoretron-Cerenkov radiation are calculated both classically and quantum mechanically by mass operator methods.
138 citations
137 citations
TL;DR: In this paper, a rigorous construction of new superselection selectors for the quantum sine-Gordon equation and the (φ·φ)2-quantum field models with explicitly broken isospin symmetry in two space-time dimensions is presented.
Abstract: A rigorous construction of new super-selection selectors — so-called “soliton-sectors” — for the quantum “sine-Gordon” equation and the (φ·φ)2-quantum field models with explicitly broken isospin symmetry in two space-time dimensions is presented These sectors are eigenspaces of the chargeQ≡∫dx(grad φ)(x) with non-zero eigenvalue The scattering theory for quantum solitons is briefly discussed and shown to have consequences for the physics in the vacuum sector A general theory is developed which explains why soliton-sectors may exist for theories in two but not in four space-time dimensions except possibly for non-abelian Yang-Mills theories
115 citations
90 citations
TL;DR: The amplitude of the magnetotransport components for Bi (magnetoresistance, Hall, magneto-Seebeck and Nernst) in the phonon-drag region have been studied as discussed by the authors.
Abstract: The amplitude of the magnetotransport components for Bi (magnetoresistance, Hall, magneto-Seebeck and Nernst) in the phonon-drag region have been studied. Measurements were extended to the quantum regime where only a few electron levels were occupied. The amplitudes of the oscillatory components are found to correlate quite well with predictions of a recent quantum transport theory (J. Phys. Soc., Japan, vol.35, p.1280 (1973)).
88 citations
TL;DR: In this paper, the authors studied the properties of local statistical correlation in non-relativistic quantum mechanics, as described by the axiomatics of von Neumann and Markof processes.
70 citations
TL;DR: In this article, the authors derived semidefinite quantum conditions for arbitrary non-separable systems, which lead to energy eigenvalues in good agreement with quantum results for both degenerate and non-degenerate two-dimensional (2D) systems.
Abstract: Semiclassical quantum conditions for arbitrary non-separable systems are derived. These lead to energy eigenvalues in good agreement with quantum results for both degenerate and non-degenerate two-dimensional (2D) systems. The applicability of these quantization rules is related to the structure of the caustics of the motion.
TL;DR: In this paper, it was shown that in three or more dimensions, the nearest-neighbor, simple-cubic, ferromagnetic, quantum Heisenberg model of spin S( = 1/2, 1, …) has a phase transition at nonzero temperature.
Abstract: We rigorously prove that in three or more dimensions, the nearest-neighbor, simple-cubic, ferromagnetic, quantum Heisenberg model of spin S(= 1/2, 1, …) has a phase transition at nonzero temperature.
TL;DR: In this article, the authors examined the nature of the quantum forces arising from the quantum potential of Madelung and Bohm and found that they are in the form of a stress tensor having diagonal and nondiagonal components.
Abstract: The fluid‐dynamical form of the Schrodinger equations is studied to examine the nature of the quantum forces arising from the quantum potential of Madelung and Bohm. It is found that they are in the form of a stress tensor having diagonal and nondiagonal components. Future studies of these quantum stress tensors in a many‐body system may shed some light on the mechanism of spontaneous symmetry breaking and the generation of vorticity in many nuclear systems.
TL;DR: In this paper, a theory of time-delay phenomena in few particle scattering has been developed and the results of this theory are used to investigate the quantum virial coefficient problem in the case of Boltzmann statistics.
TL;DR: In this article, the positions and residues of Regge poles for two interatomic potentials were calculated using both exact quantum methods and semiclassical and exact methods, and good agreement was established for the pole positions and modulus and phase of the residues.
Abstract: Semiclassical and exact quantum methods have been used to calculate the positions and residues of Regge poles for two interatomic potentials. A Lennard-Jones (6,4) potential with parameters approximating H+-Ar collisions and a Lennard-Jones (12,6) potential with parameters approximating the elastic scattering of K by HBr have been used. There is good agreement between the semiclassical and quantum calculations both for the pole positions and modulus and phase of the residues. Some properties of Regge trajectories for the Lennard-Jones (12,6) potential are also investigated.
TL;DR: The electron theory of P. A. M. Dirac as mentioned in this paper has been widely accepted as a product of quantum mechanics since the early twenty-first century, and the concept of pair annihilation dates from the turn of the twentieth century.
Abstract: "One of the most important results in the recent development of electron theory," Victor Weisskopf wrote in the mid-thirties, "is the possibility of transforming electromagnetic field energy into matter. A light quantum, for example, in the presence of other electromag netic fields in empty space, can be absorbed and transformed into matter, with the creation of a pair of electrons with opposite charge."1 By "recent," Weisskopf meant the period since P. A. M. Dirac's theory of the electron, which was published in 1928.2 Today, physicists by and large still believe that the concept of the creation of fundamental particles, as well as that of the inverse process of their destruction, is a product of quantum mechanics. In actuality, creation and annihilation concepts antedate quantum mechanics. The concept of the annihilation of pairs of oppositely charged, elementary particles,3 for example, dates from the turn of the twentieth century. It became important in astrophysics about 1924, and continued to be through the early thirties. The annihilat ing pairs were first positive and negative electrons, later protons and electrons, and finally, starting in 1931, electrons and anti-electrons. For the physicists who were building quantum mechanics, the concept was familiar and acceptable, if minor, and they included it in their theories where convenient. In Dirac's "hole" theory of 1930, for example, pair annihilation was neither novel nor central. Dirac's object was to deal with a difficulty inhering in relativistic electron
TL;DR: In this paper, it was shown that the dissipative dynamical systems with a finite and also an infinite number of degrees of freedom can be formulated in a quantum mechanical scheme by means of Nelson's stochastic quantization procedures.
TL;DR: In this article, a collinear model of the electronically nonadiabatic reaction Ba + N2O → BaO (X 1Σ), BaO(a 3Π) + N 2, treating N2 as a mass point and using accurate quantum mechanical as well as quasi-classical trajectory surface-hopping techniques is presented.
TL;DR: The detailed quantum transition state theory (DQTST) as mentioned in this paper allows quantum effects to be obtained from greatly simplified calculations by applying boundary conditions corresponding to flux in the product direction at the transition state and solving for nonreactive scattering S-matrix elements.
Abstract: The detailed quantum transition state theory (DQTST) is presented It allows quantum effects to be obtained from greatly simplified calculations by applying boundary conditions corresponding to flux in the product direction at the transition state and solving for nonreactive scattering S‐matrix elements These are used to obtain the reaction probability from specific initial states It is compared to the transition state theory (TST) and the complete quantum calculations for the planar H+H2 reaction The convergence of DQTST to the exact results is shown to be very good
TL;DR: In this article, the phase space of a light quantum in a given volume is subdivided into cells of magnitude h 3. The number of possible distributions of the light quanta of a macroscopically defined radiation over these cells gives the entropy and with it all thermodynamic properties of the radiation.
Abstract: The phase space of a light quantum in a given volume is subdivided into ’’cells’’ of magnitude h3. The number of possible distributions of the light quanta of a macroscopically defined radiation over these cells gives the entropy and with it all thermodynamic properties of the radiation.
Journal Article•
TL;DR: In this article, the authors give a complete formulation and proof of a number of assertions regarding the point spectrum of the Schrodinger operator of a many-particle system announced earlier by the author.
Abstract: The paper gives a complete formulation and proof of a number of assertions regarding the point spectrum of the Schrodinger operator of a many-particle system announced earlier by the author. In particular, conditions that the discrete spectrum of this operator be finite are obtained. The results of the work are applicable to certain specific quantum systems, for example, to univalent negative atomic ions and to diatomic molecules.Bibliography: 20 titles.
TL;DR: In this article, explicit expressions for the Green functions of arbitrary relativistic quadratic quantum systems are obtained by the integrals-of-motion method and by the coherent states method.
Abstract: Explicit expressions for the Green functions of arbitrary relativistic quadratic quantum systems are obtained by the integrals-of-motion method and by the coherent states method. The normal forms of the relativistic quadratic hamiltonians are briefly discussed. The important special cases, such as the motion of Dirac and Klein-Gordon charged particles in the fields of a plane wave and in the uniform electric and magnetic fields are investigated in detail.
01 Jan 1976
TL;DR: The shot effect of light quanta was first investigated by Hecht et al. as discussed by the authors, who showed that certain fluctuations in brightness perceived while observing very weak light sources are at least partly the result of the shot effect and used the statistical methods applied by Barnes and Czerny to determine the visual threshold, i.e., the minimum energy required to produce a visible sensation.
Abstract: Since Planck and Einstein developed the quantum theory at the beginning of the century, we know that the emission and absorption of light radiation only occurs in discrete energy quanta Even when all the conditions are kept constant the emission of individual light quanta is subject to statistical fluctuations Hence, the intensity of radiation emitted by a light source fluctuates about a constant mean These fluctuations give rise to the shot effect of the light quanta To my knowledge Barnes and Czerny (1932) were the first to investigate the possibility of visual perception of this shot effect of the quanta They showed that certain fluctuations in brightness perceived while observing very weak light sources are at least partly the result of the shot effect The statistical methods applied by Barnes and Czerny were used by Hecht et al (1942) in expanded form to determine the visual threshold, ie the minimum energy required to produce a visible sensation In research which followed this classical work of Hecht et al (1942) the main themes were the absolute thresholds and the quantum fluctuations at the absolute threshold (cf Pirenne, 1956, 1962; Baumgart, 1972) The fundamental findings of Hecht et al (1942) that a single light quantum absorbed by a human rod is sufficient to trigger an intraretinal response were thereby confirmed
01 Apr 1976
TL;DR: In this article, a quantum-mechanical method for obtaining the interaction potential from the elastic scattering amplitude is described, and two examples in which nonmonotonic potentials possessing deep wells and strong repulsions are accurately determined.
Abstract: A quantum-mechanical method for obtaining the interaction potential from the elastic scattering amplitude is described. We present two examples in which nonmonotonic potentials possessing deep wells and strong repulsions are accurately determined.
TL;DR: In this paper, the question of nonlocal effects in quantum theory is discussed in the light of the new polarization correlation measurements for positron annihilation quanta with polarimeter separations of up to 5 m recently reported by Wilson, Lowe and Butt.
Abstract: The question of nonlocal effects in quantum theory is discussed in the light of the new polarization correlation measurements for positron annihilation quanta with polarimeter separations of up to 5 m recently reported by Wilson, Lowe and Butt. We show that these results imply that nonlocal quantum correlations persist at least to distances covered by this work and rule out the possibility of a spontaneous localization process which depends only on the coherence length of the annihilation radiation.
TL;DR: In this paper, the classical generalized Langevin equation (GLE) approach to gas/solid collisions is generalized to quantum scattering using Feynman's method of partial path integration.