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

A straightforward numerical technique, based on the Gross-Pitaevskii equati on, is used to generate a self-consistent description of thermally excited states of a dilute boson gas. The process of evaporative cooling is then mo deled by following the time evolution of the system using the same equation . It is shown that the subsequent rethermalization of the thermally excited state produces a cooler coherent condensate. Other results presented show that trapping vortex states with the ground state may be possible in a two- dimensional experimental environment. [S1050-2947(99)10802-3].