Collisional Spin Transfer In An Atomic Heteronuclear Spinor Bose Gas

We observe spin transfer within a nondegenerate heteronuclear spinor atomic gas comprising a small Li-7 population admixed with a Rb-87 bath, with both elements in their F = 1 hyperfine spin manifolds. Prepared in a nonequilibrium initial state, the Li-7 spin distribution evolves through incoherent spin-changing collisions toward a steady-state distribution. We identify and measure the cross sections of all three types of spin-dependent heteronuclear collisions, namely the spin-exchange, spin-mixing, and quadrupole-exchange interactions, and find agreement with predictions of heteronuclear Li-7 -Rb-87 interactions at low energy. Moreover, we observe that the steady state of the Li-7 spinor gas can be controlled by varying the composition of the Rb-87 spin bath with which it interacts.