Suppression of Ultracold Ground-State Hyperfine-Changing Collisions with Laser Light

Using laser light tuned to a repulsive molecular potential, we have been able to suppress inelastic ground-state hyperfine-changing collisions between ultracold ^87Rb atoms. Adiabatic excitation to the repulsive curve alters the atomic trajectories and prevents the atoms from approaching close enough for the hyperfine change to occur. Experimental results show suppressions up to 50% and are in reasonable agreement with a simple Landau-Zener model. Our ability to control collisional trap loss processes may have important implications for the achievement of high densities in laser cooled samples.