Abstract

Collective motions are observed in optically thick clouds of optically trapped atoms.^1,2 Manifestations of the collective behavior include multiple bistable transitions between spherical and ring-shaped spatial distributions of the atoms and clumps of atoms rotating about a core. Detailed studies of the spherical spatial distributions are consistent with predictions of a simple model of long-range interatomic forces that arise from the radiation fields of the atoms. In particular, radiation trapping produces a long-range repulsion between the atoms. Again, a simple model that includes this repulsion as well as a vortex force produced by appropriate alignment of the laser beams reproduces many features of the rings, including approximate sizes and orbital frequencies. The model does not, however, explain the bistable transitions or the orbiting clumps of atoms. Supported by the National Science Foundation and the Office of Naval Research.

© 1993 Optical Society of America