Observation of state-to-state hyperfine-changing collisions in a Bose-Fermi mixture of Li6 and K41 atoms

Hyperfine-changing collisions are of fundamental interest for the study of ultracold heteronuclear mixtures. Here, we report a state-to-state study of the hyperfine-changing-collision dynamics in a Bose-Fermi mixture of $^{6}\mathrm{Li}$ and $^{41}\mathrm{K}$ atoms. The collision products are directly observed and the spin-changing dynamics is measured. Based on a two-body collision model, the experimental results are simultaneously fitted from which the spin-changing rate coefficient of $1.9(2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\phantom{\rule{3.33333pt}{0ex}}{\mathrm{cm}}^{3}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$ is gained, which is consistent with the multichannel quantum defect theory calculation. We further show that the contact parameter of a $^{6}\mathrm{Li}\text{\ensuremath{-}}^{41}\mathrm{K}$ mixture can be extracted from the measured spin-changing dynamics. The obtained results are consistent with the first-order perturbation theory in the weakly interacting limit. Our system offers great promise for studying spin-changing interactions in heteronuclear mixtures.