EVAPORATIVE COOLING IN A CROSSED DIPOLE TRAP

Laser cooled sodium atoms are trapped in an optical dipole force trap formed by the intersection of two 1.06 m laser beams. Densities as high as 4×1012 atoms/cm3 at a temperature of 140 K have been obtained in a 900 K deep trap. By reducing the trap depth over a 2 s interval, we have evaporatively cooled the atoms to a final temperature of 4 K at a density of 6×1011 atoms/cm3. This corresponds to a factor of 28 increase in atomic phase-space density. © 1995 The American Physical Society.