Abstract

We report the first successful use of direct quantum dynamical calculations of the cooling and formation of Bose-Einstein condensates of trapped atoms. The calculations utilize phase-space methods that have already proved successful in laser theory.^1,2 These techniques can handle large numbers of particles, but can also systematically treat departures from classical behavior including boson interactions. The results are restricted as yet to small condensates due to the relatively large numbers of modes involved. Some of the computational results are very similar to those already observed experimentally. In particular, we find quantum evaporative cooling, followed by a clear transition to a condensate; this is strongly influenced by non-classical features of the quantum dynamics. The calculations indicate additional structure, which we interpret as spontaneous formation of vortices in small condensates. These originate in the residual orbital angular momentum of the trapped atoms, which was neglected in previous studies—and would provide a significant test of the present theory.

© 1999 Optical Society of America