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

Abstract

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 Li6 by Yb174 and extract the s-wave scattering length magnitude aLi6-Yb174=(13±3)a0 from the rate of interspecies thermalization. Using forced evaporative cooling of Yb174, we achieve reduction of the Li6 temperature to below the Fermi temperature, purely through interspecies sympathetic cooling. © 2011 American Physical Society.