RESOLVED-SIDE-BAND RAMAN COOLING TO THE GROUND-STATE OF AN OPTICAL LATTICE

We trap neutral Cs atoms in a two-dimensional optical lattice and cool them close to the zero point of motion by resolved-sideband Raman coo ling. Sideband cooling occurs via transitions between the vibrational manifolds associated with a pair of magnetic sublevels, and the requir ed Raman coupling is provided by the lattice potential itself. We obta in mean vibrational excitations (n) over bar(x) approximate to (n) ove r bar, < 0.024, corresponding to a population >95% in the vibrational ground state. Atoms in the ground state of an optical lattice provide a new system in which to explore quantum state control and subrecoil l aser cooling.