Quantum degenerate mixtures of alkali and alkaline-earth-like atoms
  We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkalineearth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope 6Li with evaporatively cooled bosonic 174Yb and, separately, fermionic 173Yb.Using cross-thermalization studies, we also measure the elastic s-wave scattering lengths of both Li-Yb combinations, |a6Li-174Yb| = 1.0\pm0.2 nm and |a6Li-173Yb| = 0.9\pm0.2 nm. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems. 
Hideaki Hara, Yosuke Takasu, Yoshifumi Yamaoka, John M. Doyle, Yoshiro   Takahashi
physics.atom-ph cond-mat.quant-gas