Strongly Interacting Bose-Fermi Mixtures: Mediated Interaction, Phase Diagram, and Sound Propagation

Xin Shen, Nir Davidson, Georg M. Bruun, Mingyuan Sun, Zhigang Wu

Research output: Contribution to journalArticlepeer-review

Abstract

Motivated by recent surprising experimental findings, we develop a strong-coupling theory for Bose-Fermi mixtures capable of treating resonant interspecies interactions while satisfying the compressibility sum rule. We show that the mixture can be stable at large interaction strengths close to resonance, in agreement with the experiment, but at odds with the widely used perturbation theory. We also calculate the sound velocity of the Bose gas in the Cs133-Li6 mixture, again finding good agreement with the experimental observations both at weak and strong interactions. A central ingredient of our theory is the generalization of a fermion mediated interaction to strong Bose-Fermi scatterings and to finite frequencies. This further leads to a predicted hybridization of the sound modes of the Bose and Fermi gases, which can be directly observed using Bragg spectroscopy.

Original languageEnglish
Article number033401
JournalPhysical review letters
Volume132
Issue number3
DOIs
StatePublished - 19 Jan 2024

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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