Ultracold Rb-87 ground-state hyperfine-changing collisions in the presenceand absence of laser light - art. no. 030702

We have measured the rate of hyperfine-changing collisions between ground-s tate Rb-87 atoms in a magnetooptical trap. Using a population switching tec hnique, we directly measure the rate of these collisions in both the presen ce and absence of near-resonant trap laser light. We see a dramatic enhance ment of the collision rate by the light and observe that, in the absence of the light, the rate increases with increasing temperature. There is consis tency between this latter measured rate at temperatures below similar to 10 0 mu K and theoretical calculations constrained by other recent experiments .