3D Raman sideband cooling of cesium atoms at high density

We laser cool 5 x 10(7) Cs atoms to a spin-polarized phase space density of 1/30, the highest ever obtained by laser cooling. It is achieved by compression and polarization gradient cooling in a 3D far-off-resonant optical lattice, followed by 3D Raman sideband cooling optimized at a density of 1.5 x 10(12) atoms/cm(3), and adiabatic release. In the lattice, 23% of the sites are occupied, 95% of the atoms are in the lowest energy magnetic sublevel, and 37% are in the lowest 3D vibrational state.