Microwave Control of Low-Energy Atomic Collisions

We investigate the possibility to control the s-wave scattering length for the interaction between cold bosonic atoms by using a microwave field. Our scheme applies to any atomic species with a ground state that is split by hyperfine interaction. We discuss more specifically the case of alkali atoms and calculate the change in the scattering length for 7Li, 23Na, and 87Rb. Our results yield optimistic prospects for experiments with at least the two latter species.