Bose-Einstein-condensed systems in random potentials

Abstract

The properties of systems with Bose-Einstein condensate in external time-independent random potentials are investigated in the frame of a self-consistent stochastic mean-field approximation. General considerations are presented, which are valid for finite temperatures, arbitrary strengths of the interaction potential, and for arbitrarily strong disorder potentials. The special case of a spatially uncorrelated random field is then treated in more detail. It is shown that the system consists of three components, condensed particles, uncondensed particles and a glassy density fraction, but that the pure Bose glass phase with only a glassy density does not appear. The theory predicts a first-order phase transition for increasing disorder parameter, where the condensate fraction and the superfluid fraction simultaneously jump to zero. The influence of disorder on the ground-state energy, the stability conditions, the compressibility, the structure factor, and the sound velocity are analyzed. The uniform ideal condensed gas is shown to be always stochastically unstable, in the sense that an infinitesimally weak disorder destroys the Bose-Einstein condensate, returning the system to the normal state. But the uniform Bose-condensed system with finite repulsive interactions becomes stochastically stable and exists in a finite interval of the disorder parameter.

Latex file, final published variant

References in corpus (5)

• Fluctuations of composite observables and stability of statistical systems
• Gapless Hartree-Fock-Bogoliubov Approximation for Bose Gases
• Mean-field phase diagram of disordered bosons in a lattice at non-zero temperature
• Nonequivalent operator representations for Bose-condensed systems
• Condensation temperature of interacting Bose gases with and without disorder

Cited by in corpus (7)

• Cold Bosons in Optical Lattices
• Bose-Einstein-condensed gases in arbitrarily strong random potentials
• Stochastic Mean-Field Theory for the Disordered Bose-Hubbard Model
• Condensate and superfluid fractions for varying interactions and temperature
• Systematic Semiclassical Expansion for Harmonically Trapped Ideal Bose Gases
• Mean-field description of ultracold Bosons on disordered two-dimensional optical lattices
• Glassy features of a Bose Glass