Comments on "Stability of Tsallis entropy and instabilities of Renyi and normalized Tsallis entropies: A basis for q-exponential distributions"

It is shown that the Renyi entropy is as stable as the Tsallis entropy at least for Abe-Lesche counterexamples.Comment: 1 pag

Metal-Insulator Transition and Spin Degree of Freedom in Silicon 2D Electron Systems

Magnetotransport in 2DES's formed in Si-MOSFET's and Si/SiGe quantum wells at low temperatures is reported. Metallic temperature dependence of resistivity is observed for the n-Si/SiGe sample even in a parallel magnetic field of 9T, where the spins of electrons are expected to be polarized completely. Correlation between the spin polarization and minima in the diagonal resistivity observed by rotating the samples for various total strength of the magnetic field is also investigated.Comment: 3 pages, RevTeX, 4 eps-figures, conference paper (EP2DS-13

A Simple Theory of Condensation

A simple assumption of an emergence in gas of small atomic clusters consisting of $c$ particles each, leads to a phase separation (first order transition). It reveals itself by an emergence of ``forbidden'' density range starting at a certain temperature. Defining this latter value as the critical temperature predicts existence of an interval with anomalous heat capacity behaviour $c_p\propto\Delta T^{-1/c}$. The value $c=13$ suggested in literature yields the heat capacity exponent $\alpha=0.077$.Comment: 9 pages, 1 figur

Optically-Induced Polarons in Bose-Einstein Condensates: Monitoring Composite Quasiparticle Decay

Nonresonant light-scattering off atomic Bose-Einstein condensates (BECs) is predicted to give rise to hitherto unexplored composite quasiparticles: unstable polarons, i.e., local ``impurities'' dressed by virtual phonons. Optical monitoring of their spontaneous decay can display either Zeno or anti-Zeno deviations from the Golden Rule, and thereby probe the temporal correlations of elementary excitations in BECs.Comment: 4 pages, 3 figure

A Droplet State in an Interacting Two-Dimensional Electron System

It is well known that the dielectric constant of two-dimensional (2D) electron system goes negative at low electron densities. A consequence of the negative dielectric constant could be the formation of the droplet state. The droplet state is a two-phase coexistence region of high density liquid and low density "gas". In this paper, we carry out energetic calculations to study the stability of the droplet ground state. The possible relevance of the droplet state to recently observed 2D metal-insulator transition is also discussed.Comment: 4 pages, 4 figures. To appear in Phys. Rev. B (Rapid Communications

Spin and Charge Luttinger-Liquid Parameters of the One-Dimensional Electron Gas

Low-energy properties of the homogeneous electron gas in one dimension are completely described by the group velocities of its charge (plasmon) and spin collective excitations. Because of the long range of the electron-electron interaction, the plasmon velocity is dominated by an electrostatic contribution and can be estimated accurately. In this Letter we report on Quantum Monte Carlo simulations which demonstrate that the spin velocity is substantially decreased by interactions in semiconductor quantum wire realizations of the one-dimensional electron liquid.Comment: 13 pages, figures include

Wigner Molecules in Nanostructures

The one-- and two-- particle densities of up to four interacting electrons with spin, confined within a quasi one--dimensional ``quantum dot'' are calculated by numerical diagonalization. The transition from a dense homogeneous charge distribution to a dilute localized Wigner--type electron arrangement is investigated. The influence of the long range part of the Coulomb interaction is studied. When the interaction is exponentially cut off the ``crystallized'' Wigner molecule is destroyed in favor of an inhomogeneous charge distribution similar to a charge density wave .Comment: 10 pages (excl. Figures), Figures available on request LaTe

Correlation energy of an electron gas in strong magnetic fields at high densities

The high-density electron gas in a strong magnetic field B and at zero temperature is investigated. The quantum strong-field limit is considered in which only the lowest Landau level is occupied. It is shown that the perturbation series of the ground-state energy can be represented in analogy to the Gell-Mann Brueckner expression of the ground-state energy of the field-free electron gas. The role of the expansion parameter is taken by r_B= (2/3 \pi^2) (B/m^2) (\hbar r_s /e)^3 instead of the field-free Gell-Mann Brueckner parameter r_s. The perturbation series is given exactly up to o(r_B) for the case of a small filling factor for the lowest Landau level.Comment: 10 pages, Accepted for publication in Phys.Rev.

Autonomous generation of all Wigner functions and marginal probability densities of Landau levels

Generation of Wigner functions of Landau levels and determination of their symmetries and generic properties are achieved in the autonomous framework of deformation quantization. Transformation properties of diagonal Wigner functions under space inversion, time reversal and parity transformations are specified and their invariance under a four-parameter subgroup of symplectic transformations are established. A generating function for all Wigner functions is developed and this has been identified as the phase-space coherent state for Landau levels. Integrated forms of generating function are used in generating explicit expressions of marginal probability densities on all possible two dimensional phase-space planes. Phase-space realization of unitary similarity and gauge transformations as well as some general implications for the Wigner function theory are presented.Comment: 28 pages, 2 tables. Typos and a minor revision only section

Cyclotron effective mass of 2D electron layer at GaAs/AlGaAs heterojunction subject to in-plane magnetic fields

We have found that Fermi contours of a two-dimensional electron gas at \rmGaAs/Al_xGa_{1-x}As interface deviate from a standard circular shape under the combined influence of an approximately triangular confining potential and the strong in-plane magnetic field. The distortion of a Fermi contour manifests itself through an increase of the electron effective cyclotron mass which has been measured by the cyclotron resonance in the far-infrared transmission spectra and by the thermal damping of Shubnikov-de Haas oscillations in tilted magnetic fields with an in-plane component up to 5 T. The observed increase of the cyclotron effective mass reaches almost 5 \% of its zero field value which is in good agreement with results of a self-consistent calculation.Comment: 4 pages, Revtex, figures can be obtained on request from [email protected]; to appear in Phys. Rev. B (in press). No changes, the corrupted submission replace