All-optical formation of quantum degenerate mixtures

We report the realization of quantum degenerate mixed gases of ytterbium (Yb) isotopes using all-optical methods. We have succeeded in cooling attractively interacting Yb-176 atoms via sympathetic cooling down to below the Bose-Einstein transition temperature, coexisting with a stable condensate of Yb-174 atoms with a repulsive interaction. We have observed a rapid atom loss in Yb-176 atoms after cooling down below the transition temperature, which indicates the collapse of a Yb-176 condensate. The sympathetic cooling technique has been applied to cool a Yb-173-Yb-174 Fermi-Bose mixture to the quantum degenerate regime.