Spin-dependent inelastic collisions in spin-2 Bose-Einstein condensates

We studied spin-dependent two-body inelastic collisions in $F=2$ ⁸⁷Rb Bose-Einstein condensates both experimentally and theoretically. The ⁸⁷Rb condensates were confined in an optical trap and selectively prepared in various spin states in the $F=2$ manifold at a magnetic field of 3.0 G. The measured atom loss rates depend on the spin states of colliding atoms. We measured two fundamental loss coefficients for two-body inelastic collisions with total spins of 0 and 2. The loss coefficients determine the loss rates of all the spin pairs. The experimental results for mixtures of all spin combinations are in good agreement with numerical solutions of the Gross-Pitaevskii equations that include the effect of a magnetic field gradient.