Exciting, cooling and vortex trapping in a Bose-condensed gas

Demonstrations of Bose-Einstein condensation (BEC) in trapped dilute alkali gases provide a strong incentive for developing theoretical models of the phenomenon. A numerical model based on the Gross-Pitaevski equation (GPE) is presented that generates self-consistent thermally excited states and allows the process of evaporative cooling to be simulated. This model simulates the evaporative cooling process producing a cooler, more coherent mean-field. Explicit verification of this result is obtained from the analysis of the quasiparticle populations of the mean field. This analysis demonstrates that, under evaporative cooling, the condensate population increases and the populations of the excited modes is greatly reduced.