Interspecies thermalization in an ultracold mixture of Cs and Yb in an optical trap

We presentmeasurements of interspecies thermalization between ultracold samples of Cs-133 and either Yb-174 or Yb-170. The two species are trapped in a far-off-resonance optical dipole trap and Cs-133 is sympathetically cooled by Yb. We extract effective interspecies thermalization cross sections by fitting the thermalization measurements to a kinetic model, giving sigma(Cs)174(Yb) = (5 +/- 2) x 10(-13) cm(2) and sigma(Cs1)70(Yb) = (18 +/- 8) x 10(-13) cm(2). We perform quantum scattering calculations of the thermalization cross sections and optimize the CsYb interaction potential to reproduce the measurements. We predict scattering lengths for all isotopic combinations of Cs and Yb. We also demonstrate the independent production of Yb-174 and Cs-133 Bose-Einstein condensates using the same optical dipole trap, an important step toward the realization of a quantum-degenerate mixture of the two species.