Electron g factor in quantum wires and quantum dots

A theory of the Zeeman effect for electrons in one-and zero-dimensional semiconductor heterostructures is developed. A relation is established between the number of linearly independent components of the g-factor tensor and the point symmetry of a low-dimensional system. A specific calculation is performed for a spherical quantum dot and a cylindrical wire. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 1, 41–45 (10 January 1998)     

On triple correlations in isotropic electronic magnetohydrodynamic turbulence

The evolution of the correlation characteristics in three-dimensional isotropic electronic magnetohydrodynamic turbulence is investigated. Universal exact relations between the longitudinal and longitudinal-transverse two-point triple correlations of the components of the fluctuational magnetic fields and the rates of dissipation of the magnetic helicity and energy are obtained in the inertial range. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 9, 626–630 (10 May 1999)     

Induction mechanism of cosmic ray production and kinks in the cosmic ray spectrum

Two kinks are observed in the energy spectrum of galactic cosmic rays. It is shown that the entire spectrum can be described, to a good approximation, by a single formula obtained on the basis of the hypothesis that the particles are produced and accelerated in plasma pinches by an induction mechanism under the assumption that three hierarchical groups of currents are present—interstellar, galactic, and metagalactic. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 4, 225–230 (25 August 1996)     

Scaling function near a transition to an insulator state

Analysis of experimental results yields a scaling function of the form β(g)=121/g near the metal-insulator transition in three-dimensional systems. In two-dimensional electronic systems demonstrating a transition to an insulator state, the same relation holds for the function νβ, where ν is the critical exponent characterizing the divergence of the correlation length. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 11, 807–811 (10 December 1998)     

Extended Hydrodynamics from Enskog’s Equation for a Two-Dimensional System General Formalism

Balance equations are derived from Enskog’s kinetic equation for a two-dimensional system of hard disks using Grad’s moment expansion method. This set of equations constitute an extended hydrodynamics for moderately dense bi-dimensional fluids. The set of independent hydrodynamic fields in the present formulations are: density, velocity, temperature and also—following Grad’s original idea—the symmetric and traceless pressure tensor p _ij and the heat flux vector q ^k . An approximation scheme similar in spirit to one made by Grad in his original work is made. Once the hydrodynamics is derived it is used to discuss the nature of a simple one-dimensional heat conduction problem. It is shown that, not too far from equilibrium, the nonequilibrium pressure in this case only depends on the density, temperature and heat flux vector. PACS: 51.10.+y, 05.20.Jj, 44.10.+i, 05.70.Ln     

Evolution of spiral dynamic magnetic domains in Anger states of iron garnet films

Dynamic domain structures in the Anger state of iron garnet films are analyzed by a video micrographic technique. Data are obtained on the evolution of individual spiral domains over the lifetime of each domain. A new mechanism for the destruction of this state is discovered. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 6, 453–456 (25 March 1996)     

Hierarchical representation of generalized (nonadditive) thermodynamics

A recurrence relation leading to a probability distribution of microstates at different hierarchical levels of a nonadditive statistical system is examined (for the upper level the relation reduces to the Tsallis distribution [C. Tsallis, Physica A 221, 227 (1995)]). The processes leading to the formation and decay of a hierarchical statistical ensemble are described. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 5, 391–394 (10 March 1999)     

Infinite-dimensional representations of the Einstein group

The representations of the general linear group GL(4.R) are described. This group corresponds to the space-time transformations discussed in the general theory of relativity. Besides the well-known tensor representations, the group is also characterized by infinite-dimensional representations with integral and half-integral spins. This fact opens up a natural possibility, in principle, of constructing a covariant theory of particle fields. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 5, 309–312 (10 September 1996)     

Evolution of large-scale correlations in a strongly nonequilibrium Bose condensation process

The evolution of off-diagonal correlation functions (for the example of a single-particle density matrix) in the process of Bose condensation of an initially nonequilibrium interacting gas is discussed. Special attention is given to the character of the decay of the density matrix at distances much greater than the size of the quasicondensate region. Specifically, it is shown that the exponential decay of the density matrix necessarily presupposes the presence of a chaotic vortex structure — a tangle of vortex lines — in the system. When topological order is established but there is no off-diagonal long-range order, the density matrix decays with distance according to a power law. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 495–501 (10 April 1998)     

Two-photon fluorescence spectrum in an atom + dielectric microsphere system

A strong resonant interaction of a two-level atom with a dielectric microsphere is studied on the basis of quantum electrodynamics. The initial condition considered is one in which the atom is initially excited and the resonant mode of the microsphere has been excited by a single photon. The spectrum of two emitted photons depends strongly on the method used to excite the microsphere, i.e., on the spatial distribution of the photon energy. The most characteristic feature of the two-photon fluorescence spectrum is a strong energy correlation of the emitted photons. This correlation is expressed in the fact that the energies of the emitted photons are related by the equation of an ellipse (ω+ω ₂−2ω _vA )²+3(ω ₁−ω ₂)²= 4Ω _Rabi ² . The relation between the results obtained and the predictions of the theory of dressed states is discussed. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 3, 192–197 (10 August 1999)     

A Cosmological Model with Negative Constant Deceleration Parameter in a General Scalar-Tensor Theory of Gravitation

Spatially homogeneous and anisotropic LRS Bianchi type-I metric is considered in the framework of Nordtvedt-Barker’s general scalar-tensor theory of gravitation when the source for the energy momentum tensor is a perfect fluid. With the help of a special law of variation for Hubble’s parameter proposed by Berman (Nuovo Cim. B. 74:182, 1983) a cosmological model with negative constant deceleration parameter is obtained. Some physical and kinematical properties of the model are also discussed.     

A simple approach to the evaluation of the hall conductivity in impure metals within the green function formalism

A simple method of dealing with the Hall effect in metals with short-ranged impurities in a weak magnetic field is proposed. The method is based on a Schwinger representation for the electron Green function in the magnetic field. The efficacy of the method is demonstrated on a calculation of the antisymmetric components of the conductivity tensor at finite wave vector. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 2, 141–145 (25 January 1998) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Obtaining the Weyl tensor from the Bel–Robinson tensor

The algebraic study of the Bel–Robinson tensor proposed and initiated in a previous work (Ferrando and Sáez in Gen Relativ Gravit 41:1695–1715, 2009) is achieved. The canonical form of the different algebraic types is obtained in terms of Bel–Robinson eigen-tensors. An algorithmic determination of the Weyl tensor from the Bel–Robinson tensor is presented.     

Studies of the electron density at the nucleus and radial expectation values of the ground state for lithium-like systems from Z=11 to 18

The electron density at the nucleus ρ(0) and radial expectation values 〈rⁿ〉 (n=-2–10) of the ground state for lithium-like systems from Z=11 to 18 are calculated with the full core plus correlation wave functions. By using these obtained expectation values, accurate inequalities of radial expectation values derived by Gálvez and Porras [Phys. Rev. A 44, 144 (1991)] are examined and verified. The final results show that the full core plus correlation wave functions for lithium-like systems with higher nuclear charge are also accurate in the full configuration space and can give satisfactory electron density at the nucleus and radial expectation values.     

Splitting of a high-energy photon in a strong Coulomb field

The helical splitting amplitudes of a high-energy photon in an external Coulomb field are found exactly with respect to Zα. Both screened and unscreened potentials are investigated. The treatment is carried out within the semiclassical approach, which is valid for small angles between the momenta of all photons. A new representation is used for the semiclassical electronic Green’s function. The resulting expressions are analyzed in detail for the case of transverse components of the momenta of the final photons that are large compared with the electron mass. Zh. éksp. Teor. Fiz. 112, 1921–1940 (December 1997)     

New type of excitonic radiation in the solid solutions CdS1−x Sex

Manifestations of bulk crystalline regions with stacking faults are detected in the reflection and photoluminescence spectra of CdS_1-x Sex crystals with a variety of compositions. The magnitude of the crystal-field anisotropy and the spin-orbit splitting in these crystals are estimated. It is shown that reabsorption affects the form of the photoluminescence in crystals with stacking faults. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 3, 221–225 (10 August 1999)     

An approximate expression for the galvanomagnetic tensor

Using the iterative solution to the Boltzmann equation for electrons in d.c. electric and magnetic fields, an expression for the resistivity tensor can be obtained in the form of an infinite series. This series can be approximated by retaining only the first two terms. In the cases where relaxation times exist — in the sense that the collision term in the Boltzmann equation can be written asg(k)/τ(k), whereτ(k) is the relaxation time, andf (k) = f _E(ɛ k) + [∂f _E(εk)/∂ε]·g(k) the distribution function for electrons with wavevectork — this approximation is exact. For polyvalent metals in the one-OPW approximation, the complete galvanomagnetic tensor can be obtained using this approximation and the result differs from that obtained by using a time of relaxation given by an expression suggested byZiman. A calculation for a simple model Fermi surface, with screened Coulomb scattering, is carried out and the results compared with those of the relaxation time approximation.     

Anisotropy of the superconducting properties of YBa2Cu3O7−x single crystals with reduced oxygen content

In an investigation of the resistivity anisotropy of YBa₂Cu₃O_7−x single crystals with suboptimal oxygen content it is observed that the superconducting transition for the component ρc of the resistivity tensor is shifted to lower temperatures with respect to the transition for the component ρab. A similar shift is also observed for the transition in the temperature dependence of the dynamic magnetic susceptibility. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 309–313 (25 August 1998)     

On strategies for opaque and translucent eavesdropping in a quantum-cryptographical system

The confidentiality of a quantum-cryptographical system based on the energy-time uncertainty relation is discussed with respect to opaque and translucent eavesdropping strategies. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 7, 559–564 (10 April 1997)