Ultracold dimer association induced by a far-off-resonance optical lattice

We investigate a process by which an optical lattice potential can transfer two unbound ultracold atoms in a lattice site to an untrapped dimer. The transition is mediated by the anharmonic terms in the lattice potential, which couple the relative and center-of-mass coordinates of the two atoms. We calculate the rate of decay from the ground state in a lattice cell to the last bound dimer state as a function of the s-wave scattering length and optical lattice depth. The decay rate has a maximum value of 9x10-6ER/h, where ER is the atomic recoil energy. Consequently typical molecular production rates are much smaller than 1 s-1. Explicit results are given for 133Cs atoms tuned near a Feshbach resonance