Critical temperatures of a trapped Bose gas: mean-field theory and fluctuations

Abstract

We investigate the possibilities of distinguishing the mean-field and fluctuation effects on the critical temperature of a trapped Bose gas with repulsive interatomic interactions. Since in a direct measurement of the critical temperature as a function of the number of trapped atoms these effects are small compared to the ideal gas results, we propose to observe Bose-Einstein condensation by adiabatically ramping down the trapping frequency. Moreover, analyzing this adiabatic cooling scheme, we show that fluctuation effects can be lead to the formation of a Bose condensate at frequencies which are much larger that those predicted by the mean field theory.