Evanescent-wave trapping and evaporative cooling of an atomic gas at the crossover to two dimensions -: art. no. 173001

A dense gas of cesium atoms at the crossover to two dimensions is prepared in a highly anisotropic surface trap that is realized with two evanescent light waves. Temperatures as low as 100 nK are reached with 20 000 atoms at a phase-space density close to 0.1. The lowest quantum state in the tightly confined direction is populated by more than 60%. The system provides atoms at a mean distance from the surface as low as 1 mum, and offers intriguing prospects for future experiments on degenerate quantum gases in two dimensions.