Interacting electrons in a one-dimensional random array of scatterers - A Quantum Dynamics and Monte-Carlo study

The quantum dynamics of an ensemble of interacting electrons in an array of random scatterers is treated using a new numerical approach for the calculation of average values of quantum operators and time correlation functions in the Wigner representation. The Fourier transform of the product of matrix elements of the dynamic propagators obeys an integral Wigner-Liouville-type equation. Initial conditions for this equation are given by the Fourier transform of the Wiener path integral representation of the matrix elements of the propagators at the chosen initial times. This approach combines both molecular dynamics and Monte Carlo methods and computes numerical traces and spectra of the relevant dynamical quantities such as momentum-momentum correlation functions and spatial dispersions. Considering as an application a system with fixed scatterers, the results clearly demonstrate that the many-particle interaction between the electrons leads to an enhancement of the conductivity and spatial dispersion compared to the noninteracting case.Comment: 10 pages and 8 figures, to appear in PRB April 1

Thermodynamics of hot dense H-plasmas: Path integral Monte Carlo simulations and analytical approximations

This work is devoted to the thermodynamics of high-temperature dense hydrogen plasmas in the pressure region between $10^{-1}$ and $10^2$ Mbar. In particular we present for this region results of extensive calculations based on a recently developed path integral Monte Carlo scheme (direct PIMC). This method allows for a correct treatment of the thermodynamic properties of hot dense Coulomb systems. Calculations were performed in a broad region of the nonideality parameter $\Gamma \lesssim 3$ and degeneracy parameter $n_e \Lambda^3 \lesssim 10$. We give a comparison with a few available results from other path integral calculations (restricted PIMC) and with analytical calculations based on Pade approximations for strongly ionized plasmas. Good agreement between the results obtained from the three independent methods is found.Comment: RevTex file, 21 pages, 5 ps-figures include

The electronic resonances in expanding non-neutral ultracold plasma

We present a calculation of the natural oscillation spectrum of a bounded non-neutral ultra-cold plasma. The frequencies of these oscillations are recorded in experiments as absorption resonances of high-frequency electric field. Dependence of the frequency of these resonances on the charge imbalance and on the expansion time is obtained. Good agreement with experiment is note

Laser cooling of 7Li atoms in a magneto-optical trap

A setup for laser cooling and confining of 7Li atoms in a magneto-optical trap has been built. The possibility of cooling and trapping of 7Li atoms in a wide range of frequency detuning of the cooling laser has been proved experimentally. Independent information on the density and number of ultracold 7Li atoms on various ground-state sublevels, as well as on the temperature of the atoms, has been obtained with the use of a probing tunable laser. This information is important for preparing an ultracold plasma and Rydberg matter

The correlation length exponent of the hard-sphere Bose-Einstein condensate by path integral calculations

The correlation length exponent ν has been calculated for the hard-sphere Bose-Einstein condensation by path integral Monte Carlo simulations in the Feynman formulation of quantum mechanics. This new calculation method allows to determine the density dependence of the correlation length exponent. It is shown that ν, being equal to unity for an ideal gas, is close to 2/3 for boson hard spheres in a wide range of gas densities with an accuracy of 10%

Bose condensation in dilute gas of hard spheres with attraction

Critical temperature is calculated for Bose-Einstein condensation of hard spheres with attraction using the path-integral Monte Carlo (PIMC) method and finite-size scaling. It is demonstrated that the scattering length is not the only parameter which the critical temperature depends on. It is also shown that Bose condensation may be observed in the case of negative scattering length