Laser cooled sodium atoms are trapped in an optical dipole force trap formed by the intersection of two 1.06 μm laser beams. Densities as high as $4\times {10}^{12}$ atoms/c${\mathrm{m}}^3$ at a temperature of $\sim 140$ μK have been obtained in a $\sim 900$ μK deep trap. By reducing the trap depth over a 2 s interval, we have evaporatively cooled the atoms to a final temperature of $\sim 4$ μK at a density of $6\times {10}^{11}$ atoms/c${\mathrm{m}}^3$. This corresponds to a factor of 28 increase in atomic phase-space density.

• Received 17 November 1994

DOI:https://doi.org/10.1103/PhysRevLett.74.3577