arXiv subjects

G. E. Astrakharchik

Publications and source records attributed to G. E. Astrakharchik.

94 records · Page 6Linked to original sources

arXiv2002

Correlation functions and momentum distribution of one-dimensional Bose systems

The ground-state correlation properties of a one-dimensional Bose system described by the Lieb-Liniger Hamiltonian are investigated by using exact quantum Monte Carlo techniques. The pair distribution function, static structure factor, one-body density matrix and momentum distribution of a homogeneous system are calculated for different values of the gas parameter ranging from the Tonks-Girardeau to the mean-field regime. Results for the momentum distribution of a harmonically trapped gas in configurations relevant to experiments are also presented.

cond-mat↗

arXiv2002

Quantum Monte Carlo study of the 3D-1D crossover for a trapped Bose gas

We investigate the cross-over from three to one dimension in a Bose gas confined in highly anisotropic traps. By using Quantum Monte-Carlo techniques, we solve the many-body Schrodinger equation for the ground state and obtain exact results for the energy per particle and the mean square radii of the cloud in the transverse and longitudinal direction. Results are compared with the predictions of mean-field theory obtained from the Gross-Pitaevskii equation and with the 1D Lieb-Liniger equation of state. We explicitly prove the occurrence of important beyond mean-field effects, including the appearance of Fermi-like properties as the system enters the Tonks gas regime.

cond-mat↗

arXiv2001

Superfluidity vs Bose-Einstein condensation in a Bose gas with disorder

We investigate the phenomenon of Bose-Einstein condensation and superfluidity in a Bose gas at zero temperature with disorder. By using the Diffusion Monte-Carlo method we calculate the superfluid and the condensate fraction of the system as a function of density and strength of disorder. In the regime of weak disorder we find agreement with the analytical results obtained within the Bogoliubov model. For strong disorder the system enters an unusual regime where the superfluid fraction is smaller than the condensate fraction.

cond-mat↗

arXiv1999

Properties of two - dimensional dusty plasma clusters

Two-dimensional classical cluster of particles interacting through a screened Coulomb potential is studied. This system can be used as a model for "dusty particles" in high-frequency discharge plasma. For systems consisting of N = 2 - 40 particles and confined by a harmonic potential we find ground-state configurations, eigenfrequencies and eigenvectors for the normal modes as a function of the Debye screening length R_D in plasma. Variations in R_D cause changes in the ground-state structure of clusters, each structural rearrangement can be considered as a phase transition of first or second order (with respect to parameter R_D). Monte Carlo and molecular dynamics are used to study in detail the melting of the clusters as the temperature is increased. By varying the density and the temperature of plasma, to which the particles are immersed, one can modulate thermodynamical properties of the system, transforming it in a controllable way to an ordered (crystal-like), orientationaly disordered or totally disordered (liquid-like) states. The possibility of dynamical coexistence phenomena in small clusters is discussed.

cond-mat.mes-hall↗