Collective excitations of a quasi two-dimensional BEC: beyond mean field theory

Abstract

Collective excitations of a quasi two dimensional Bose-Einstein Condensate, which is subjected to an effective potential including beyond mean field effects, are studied. In the mean field regime, the sudden increase of the collective excitation frequency to infinity, indicating a collapse of the condensate is followed by its reappearance. It is found that the beyond mean field modifications prevent the reappearance of the excitation frequencies. Modifications in the potential are also found to prevent both attractively and repulsively interacting condensates from supporting the constant frequency breathing mode.