Efficient Laser Cooling of 85Rb Atoms to the Recoil Temperature Limit

We demonstrate laser cooling of 85Rb atoms in a two-dimensional optical lattice. We follow the two-step degenerate Raman sideband cooling scheme, Kerman el al., Phys. Rev. Lett. 84, 439 (2000), where a fast cooling of atoms to an auxiliary state followed by a slow cooling to a dark state. This method has the advantage of independent control of the heating rate and cooling rate from the optical pumping beam. We operate the lattice at Lamb-Dicke parameter eta=0.45 and show the cooling of spin-polarized 85Rb atoms to the recoil temperature in both dimension within 2.4 ms with 90% of initial atom numbers.