Dynamics of a degenerate Cs-Yb mixture with attractive interspecies interactions

Abstract

We probe the collective dynamics of a quantum degenerate Bose-Bose mixture of ^{133}Cs and ^{174}Yb with attractive interspecies interactions. Specifically, we excite vertical center-of-mass oscillations of the Cs condensate. We observe significant damping for the Cs dipole mode, due to the rapid transfer of energy to the larger Yb component and the ensuing acoustic dissipation. Numerical simulations based on coupled Gross-Pitaevskii equations provide excellent agreement with experiment and additionally reveal the possibility of late-time revivals (beating), which are found to be highly sensitive to the Cs and Yb atom number combinations. By further tuning the interaction strength of Cs using a broad Feshbach resonance, we explore the stability of the degenerate mixture. We observe collapse of the Cs condensate mediated by the attractive Cs-Yb interaction when a_{Cs}<50a_{0}, well above the single-species collapse threshold, in good agreement with simulations.