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.
Highlights
Superfluid mixtures formed of ultracold atoms offer a versatile playground for studies of binary fluid dynamics in both Bose-Bose and Bose-Fermi mixtures
We find that the attractive interspecies interaction results in complicated coupled dynamics, as Cs pulls along Yb in the region of Cs-Yb overlap
We have probed the collective dynamics of a quantum degenerate Bose-Bose mixture of Cs and 174Yb with attractive interspecies interactions
Summary
Superfluid mixtures formed of ultracold atoms offer a versatile playground for studies of binary fluid dynamics in both Bose-Bose and Bose-Fermi mixtures. Experimental control in ultracold atomic mixtures allows the balance of the interand intraspecies interactions to be tuned, enabling further manipulation of the coupled dynamics and stability of the system. This can result in novel bound states such as bright-dark solitons [12] and exotic vortex lattices [13,14] and enable miscibility studies [15]. We probe the collective dynamics and stability of a quantum degenerate Bose-Bose mixture of 133Cs and 174Yb with an attractive interspecies interaction characterized by the scattering length aCsYb = −75 a0 [22]. We probe the stability of the mixture by tuning the Cs interaction strength across the collapse threshold, demonstrating Yb-mediated collapse of the Cs BEC, well above the single-species collapse threshold
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