Ultracold87Rbground-state hyperfine-changing collisions in the presence and absence of laser light

Abstract

We have measured the rate of hyperfine-changing collisions between ground-state ${}^{87}\mathrm{Rb}$ atoms in a magneto-optical trap. Using a population switching technique, we directly measure the rate of these collisions in both the presence and absence of near-resonant trap laser light. We see a dramatic enhancement of the collision rate by the light and observe that, in the absence of the light, the rate increases with increasing temperature. There is consistency between this latter measured rate at temperatures below $\ensuremath{\sim}100$ $\ensuremath{\mu}\mathrm{K}$ and theoretical calculations constrained by other recent experiments.