CRITICAL-TEMPERATURE OF A TRAPPED BOSE-GAS - MEAN-FIELD THEORY AND FLUCTUATIONS

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 at oms these effects are small compared to the ideal gas results, we prop ose to observe Bose-Einstein condensation by adiabatically ramping dow n the trapping frequency. Moreover, analyzing this adiabatic cooling s cheme, we show that fluctuation effects can lead to the formation of a Bose-Einstein condensate at frequencies which are much larger than th ose predicted by the mean-field theory.