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

TL;DR

This study investigates the collective dynamics and stability of a quantum degenerate Cs-Yb mixture with attractive interactions, revealing damping, energy transfer, revivals, and collapse phenomena through experiments and simulations.

Contribution

It provides new insights into the dynamics and stability of degenerate Bose-Bose mixtures with attractive interspecies interactions, including the observation of collapse and the role of Feshbach tuning.

Findings

Significant damping of Cs dipole mode due to energy transfer to Yb.

Observation of collapse of Cs condensate at specific interaction strengths.

Numerical simulations show excellent agreement and reveal potential revivals.

Abstract

We probe the collective dynamics of a quantum degenerate Bose-Bose mixture of Cs and $^{174}$Yb with attractive interspecies interactions. Specifically, we excite vertical center of mass oscillations of the Cs condensate, and 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, 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, and observe collapse of the Cs condensate mediated by the attractive Cs-Yb interaction when $a_{\mathrm{Cs}}<50 \, a_0$, well above the single-species collapse threshold, in good agreement with simulations.