Light-induced ultracold spin-exchange collisions

Abstract

We study collisional loss rates due to spin-exchange collisions in very-low-intensity ${}^{87}\mathrm{Rb}$ magneto-optical traps. The loss rate exhibits an unpredicted intensity dependence for low intensities, accounting for a large disparity between loss rates observed in light-force traps and magnetically confined Bose condensates. Possible collision mechanisms considered include light-altered collision phase shifts, flux enhancement, and excited-state hyperfine changing collisions.