Behavior of Bose-Einstein Condensate under Gaussian Random Potential

Abstract

In this thesis we give a theoretical review of Bose-systems under spatially random potentials with arbitrary strength of disorder and interactions. Stochastic mean fie ld approximation is used for the description of such ra ndom systems because in such cases perturbation theory yields invalid results. Further we specify the type of the random potential for the Bose-system and use Gaussian random potential with local correlation. We show that ideal Bose-condensed system is stochastically unstable even with finite strength of disorder. For the interacting Bose-condensed system, when we increase the strength of disorder the condensa te fra ction decreases and the glassy fraction increases. At a critical value of disorder strength, the condensate fraction and glassy fraction jumps to zero and the system undergoes a first order phase transition.