Showing papers on "Quantum published in 1972"
Book•
01 Jan 1972
160 citations
TL;DR: In this article, the symmetry properties of a particle interacting with an electromagnetic circularly polarized plane wave were considered and the classical and quantum analysis of the stability group of the plane wave exhibits the origin of the mass shift of the particle.
Abstract: We consider the symmetry properties of a particle interacting with an electromagnetic circularly polarized plane wave. The classical and quantum analysis of the stability group of the plane wave exhibits the origin of the mass shift of the particle. The Chakrabarti’s dynamical representation of the Poincare group is rederived and its physical meaning is given.
133 citations
69 citations
TL;DR: In this paper, a quantum-mechanical transport equation (QMTE) is derived which is applicable to a wide range of problems involving the interaction of radiation with atoms or molecules which are also subject to collisions with perturber atoms.
Abstract: A quantum-mechanical transport equation (QMTE) is derived which should be applicable to a wide range of problems involving the interaction of radiation with atoms or molecules which are also subject to collisions with perturber atoms. The equation follows the time evolution of the macroscopic atomic density matrix elements of atoms located at classical position R and moving with classical velocity v. It is quantum mechanical in the sense that all collision kernels or rates which appear have been obtained from a quantum-mechanical theory and, as such, properly take into account the energy-level variations and velocity changes of the active (emitting or absorbing) atom produced in collisions with perturber atoms. The present formulation is better suited to problems involving high-intensity external fields, such as those encountered in laser physics.
60 citations
TL;DR: In this article, an exact solution for the retarded Green's function of the radiation field is calculated for a quantum model consisting of three interacting boson fields-photon, exciton, and phonon.
Abstract: Quantum field-theoretical methods are applied to the problem of determining how the exciton-lattice interaction affects the dispersion of an electromagnetic field associated with the exciton-radiation interaction. An exact solution for the retarded Green's function of the radiation field is calculated for a quantum model consisting of three interacting boson fields-photon, exciton, and phonon. The classical Green's function of a damped-harmonic-oscillator model of a dielectric is shown to be a special case of this quantum Green's function. Two sets of dispersion relations are derived; one set has well-defined energy, the other has well-defined momentum. Results of the theory clearly suggest that the exciton-lattice interaction is capable of literally damping out the "polariton" effects associated with the exciton-radiation interaction in the field solutions with well-defined energy. A Poynting theorem based on the classical model is also derived which includes effects of both spatial dispersion and damping.
57 citations
TL;DR: In this article, the positions and shapes of the multiple quantum resonances, caused by a large intensity RF field, using a continued fraction solution presented in an earlier paper, were calculated.
Abstract: For Pt. I see ibid., vol.5, no.4, 878. The author presents calculations of the positions and shapes of the multiple quantum resonances, caused by a large intensity RF field, using a continued fraction solution presented in an earlier paper. The shift of the line is given for up to 11 quantum transitions and the width up to 7 quantum transitions. It is shown in which parameter ranges the results differ from earlier work by Shirley and Cohen-Tannoudji and Haroche.
55 citations
TL;DR: In this paper, the evolution of the intensity and photon statistics of the second harmonic light were studied in the presence of a periodicity in the intensity of the emitted radiation and the photon statistics were predicted to undergo a sharp transition following the first maximum of intensity.
Abstract: Nonlinear optical effects where quantum mechanical predictions are at variance with the results of classical calculations are studied. Certain initial conditions, those of unstable equilibrium or those that lead to unstable equilibrium, classically, give rise to an aperiodicity in the intensity of the emitted radiation. One example of such a system is second-harmonic generation, which is studied in detail because of the potential amenability of the aperiodicity to experimental observation. Numerical and analytic predictions for the evolution of the intensity and photon statistics of the second harmonic light are presented. The photon statistics of the second harmonic light are predicted to undergo a sharp transition following the first maximum of the intensity.
54 citations
51 citations
50 citations
TL;DR: Phenomena well known in chemical spectroscopy are used to explain muscular contraction; fundamental reasons for excluding alternative explanations are outlined.
Abstract: Phenomena well known in chemical spectroscopy are used to explain muscular contraction; fundamental reasons for excluding alternative explanations are outlined.
45 citations
TL;DR: The critical energy for stochasticity observed in classical systems, for physical values of the parameters in the problem, is of the order of magnitude of the quantum zero-point energy.
[...]
TL;DR: In this paper, a general technique, algebraic quantization, is provided for going from classical (c) paradigms, typically discrete logical structures, to q analogs.
Abstract: Quantum concepts can be applied to space-time processes to make a quantum (q) theory that is free of the possibility of divergencies inherent in classical continuum theories, yet causal, Lorentz-invariant, and asymptotically Poincar\'e-invariant for large times. A general technique, algebraic quantization, is provided for going from classical (c) paradigms, typically discrete logical structures, to q analogs. Applied to the two-dimensional c checker-board, algebraic quantization gives a q theory of time and space asymptotic to the four-dimensional Minkowski c theory in the limit of large time. Applied to the simplest dynamics on such a checkerboard, a piece that makes the same move again and again, algebraic quantization gives a q dynamics asymptotic to a massless spin-\textonehalf{} two-component dynamics in the same limit. The quantum of time, if it exists, must have spin \textonehalf{}. Some features of general relativity such as curvature seem plausible consequences of a quantum theory of space-time processes.
CERN1
TL;DR: In this paper, the energy of 5g-4f muonic X-rays have been measured in nat Hg and 203 Tl with an accuracy of about 25 eV They are found to be smaller than theoretical energies including recently revised calculations of higher-order vacuum polarization, by about two standard deviations
Journal Article•
TL;DR: In this article, the authors obtain continuity properties of additive measures on the projection lattice of a continuous von Neumann factor, and prove a generalised form of Gleason's theorem.
Abstract: We obtain some continuity properties of countably additive measures on the projection lattice of a continuous von Neumann factor. In the hyperfinite case, we prove a generalised form of Gleason’s theorem. RESUME. 2014 Nous obtenons quelques proprietes de continuite des mesures denombrablement additives sur le treillis des projecteurs d’un facteur de von Neumann continu. En le cas hyperfini, nous prouvons une forme generalisee du theoreme de Gleason.
TL;DR: A general quantum mechanical approach for treating a great number of rate processes is developed and the temperature dependence of the rate constants is discussed.
Abstract: A general quantum mechanical approach for treating a great number of rate processes is developed and the temperature dependence of the rate constants is discussed.
TL;DR: In this paper, the trajectory and radiation spectrum of a relativistic electron at strong radiation damping were given in forms which can be directly tested in experiments using megagauss magnetic fields as targets for high energy electron beams.
Abstract: A number of astrophysical discoveries and laboratory developments have prompted the need to consider synchrotron emission including effects of radiation reaction and quantum corrections In this article we first solved the Lorentz-Dirac equation to give the trajectory and radiation spectrum of a relativistic electron at strong radiation damping The results are presented in forms which can be directly tested in experiments using megagauss magnetic fields as targets for high energy electron beams The quantum mechanical effects which often intermingle with the classical radiation reaction effects are discussed A quantum mechanical calculation including the effects of energy damping and quantum fluctuations is presented The results obtained for a single electron are applied to an ensemble of electrons The characteristics of the emission spectra are summarized in the final section for various ranges of field intensity and particle energy
TL;DR: In this article, the methods of nonstandard analysis are demonstrated as a preliminary step for the construction of the nonstandard λ:φ24: model and elementary quantum mechanical problems are solved and the renormalization of the scalar field (Yukawa interaction) is investigated.
Abstract: The methods of nonstandard analysis are demonstrated as a preliminary step for the construction of the nonstandard λ:φ24: model. Elementary quantum mechanical problems are solved and the renormalization of the scalar field (Yukawa interaction) is investigated.
TL;DR: In this article, a method used by Hemmer and Jancovici to calculate quantum corrections to the equation of state for a hard-sphere gas is extended to cover the case of a more general intermolecular potential.
Abstract: A method used by Hemmer and Jancovici to calculate quantum corrections to the equation of state for a hard-sphere gas is extended to cover the case of a more general intermolecular potential. The basis of the method is an expansion of the partition function about its classical limit, the terms in the expansion being integrals over products of classical correlation functions and certain "modified" quantum Ursell functions. Conditions are discussed under which this series can be truncated to give the quantum corrections to a specified order in $h$ (Planck's constant). A calculation of the first quantum correction is carried out for the square-well-plus-hard-core potential.
01 Jan 1972
TL;DR: In this article, the fundamental equation of many physical theories in three equations, known in classical fields of the macrocosm as definition, balance and constitutive equations, whose operators enjoy peculiar properties.
Abstract: : Many physical theories exhibit a common mathematical structure that is independent of the physical contents of the theory and is common to discrete and continuum theories, be they of classic, relativistic or quantum nature. The starting point of this structure is the possibility of decomposing the fundamental equation of many physical theories in three equations, known in classical fields of the macrocosm as definition, balance and constitutive equations, whose operators enjoy peculiar properties. The properties are as follows: the operator of balance equation is the adjoint, with respect to an opportune bilinear functional, of the operator of definition equation (if the last is linear) or of its Gateaux derivative (if it is nonlinear). Moreover, the operator of constitutive equation is symmetric (when it is linear) or has symmetric Gateaux derivative (when it is nonlinear). Such a peculiar decomposition permits us to obtain a profound introspection into the mathematical structure of a theory. The fact that this decomposition can be achieved in a large number of physical theories and the fact that when it exists we can deduce easily a large number of mathematical properties, suggest constructing a mathematical model for physical theories.
TL;DR: In this article, a general method for obtaining the density expansion of quantum transport coefficients and other response functions is presented, which completely bypasses the problems encountered when one considers extension of the inversion technique used for classical systems.
TL;DR: In this article, the spreading of a quantum mechanical wave packet is studied from two apparently equivalent points of view: one prescription predicts spreading while the other does not, and reasons for this anomaly are discussed.
Abstract: The spreading of a quantum mechanical wave packet is studied from two apparently equivalent points of view. For certain classes of wave functions, one prescription predicts spreading while the other does not. Reasons for this anomaly are discussed.
TL;DR: In this article, it was shown that the core-level binding energy shifts depend on the same approximation that was made by Schwartz in deriving the potential model, and several implications for the calculation of these shifts are pointed out.
TL;DR: In this article, the photochemical principles involved in quantum yield determinations are described and various techniques and calculations used in determining the quantum yield of photosynthetic reactions are also discussed.
Abstract: Publisher Summary This chapter describes the photochemical principles involved in quantum yield determinations. The various techniques and calculations used in quantum yield determinations of photosynthetic reactions are also discussed. The photosynthetic reactions involve endothermic photochemical reactions by the absorption of light quanta. It follows that the determination of the quantum yield or quantum efficiency of photosynthesis can be important in elucidating the overall photochelnical mechanism of this biological process. Radiant energy is absorbed in discrete units called “quanta.” Only absorbed light quanta induce photochemical events. In the primary photochemical process, a single absorbed photon excites a single photoreactive molecule. There are certain essential technical requirements for quantum yield determinations: (1) a source of monochromatic light, (2) a method for measuring the incident quantum intensity of the monochromatic light source, (3) a method for measuring either directly or indirectly the fraction of the incident quantum intensity absorbed by the reacting system, and (4) a method for assaying the resulting photochemical process under light limiting conditions.
TL;DR: For example, this article argued that the statistical laws of quantum theory refer to a population of particles endowed with positions, and momenta (and mass-energy, and various other physical properties such as spin).
Abstract: In his writings on quantum theory, early and late, Karl Popper has steadfastly maintained that the quantum-theoretic world-view is much closer to common sense than the theory's originators have claimed in their philosophical moments. As against Bohr, who held that quantum theory requires "a limitation of the well-defined application of space-time concepts" to atomic objects ([1966], p. 5) and consequently "a radical revision of our attitude towards the problem of physical reality" ([1961], p. 60), Popper has claimed that "the statistical laws of the theory. . refer to a population of particles... which are ... endowed with positions, and momenta (and mass-energy, and various other physical properties such as spin)" ([1967], p. 21; cf. [1935], Ch. IX). Presumably, then, his view is that for every system S and observable A, there is a real number r such that "A = r" is true of S.
TL;DR: In this article, a completely consistent quantum physical picture of fracture can be obtained by introducing a de Broglie wavelength for a stress pulse, where the uncertainty relation is used to determine threshold conditions for wave-crack interaction.
Patent•
04 May 1972TL;DR: The frequency matched quantum counter principle is used for converting infrared radiation into visible or near visible radiation as mentioned in this paper, and the return transition of electrons from the upper state to the ground state which occurs with emission of visible or far visible radiation can then be detected with a photodetector.
Abstract: The frequency matched quantum counter principle is used for converting infrared radiation into visible or near visible radiation. The quantum counter or detection screen utilize the properties of atoms which are capable of absorbing infrared signal radiation inducing electronic transition from a ground state to an intermediate state. Furthermore these atoms are capable of being pumped from the intermediate state to an upper state. The return transition of electrons from the upper state to the ground state which occurs with emission of visible or nearvisible radiation can then be detected with a photodetector. The pumping of the active atoms of the quantum counter is accomplished by means of a first laser which is made of a material which contains the same atoms as those effective in the quantum counter. The radiation from this first laser may be modulated by a suitable modulator or may be modified or perturbed by an object to be viewed or depicted. For signal generation a second laser can be used in which the radiation is generated by the same active atoms as the quantum counter. By way of example, the active atoms may consist of triply ionized erbium or triply ionized neodynium both in a suitable matrix.