Decoherence of spin oscillations in an ultracold F=1 sodium gas

An ultracold F=1 sodium gas prepared in a superposition of the m=+1, 0, -1 magnetic sublevels displays nonlinear spin dynamics. The dynamics are driven by coherent spin mixing collisions, where a pair of m=0 atoms is converted into a pair with m=+1 and m=-1. In the noncondensed thermal gas, we find that the resulting population oscillations decay over several hundred milliseconds. We present measurements of the decay time as a function of applied magnetic field and initial state, and discuss possible causes of the decay.