Laser cooling of Rb85 atoms to the recoil-temperature limit

We demonstrate the laser cooling of $^{85}\mathrm{Rb}$ atoms in a two-dimensional optical lattice. We follow the two-step degenerate Raman sideband cooling scheme [Kerman et al., Phys. Rev. Lett. 84, 439 (2000)], where a fast cooling of atoms to an auxiliary state is 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 a Lamb-Dicke parameter $\ensuremath{\eta}=0.45$ and show the cooling of spin-polarized $^{85}\mathrm{Rb}$ atoms to the recoil temperature in both dimensions within 2.4 ms with the aid of adiabatic cooling.