Sympathetic cooling in an optically trapped mixture of alkali and spin-singlet atoms

We report on the realization of a stable mixture of ultracold lithium and ytterbium atoms confined in a far-off-resonance optical dipole trap. We observe sympathetic cooling of $^{6}$Li by $^{174}$Yb and extract the s-wave scattering length magnitude $|a_{^{6}Li-^{174}Yb}|$ from the rate of inter-species thermalization. Using forced evaporative cooling of $^{174}$Yb, we achieve reduction of the $^{6}$Li temperature to below the Fermi temperature, purely through inter-species sympathetic cooling. These observations constitute a starting point for experiments with simultaneously quantum degenerate species, and pave the way toward synthesis of paramagnetic, polar molecules. [Ref. arXiv:1101.5142]