Strongly interacting Bose-Fermi mixture: mediated interaction, phase diagram and sound propagation

Abstract

Motivated by recent surprising experimental findings, we develop a strong-coupling theory for Bose-Fermi mixtures capable of treating resonant inter-species 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 ${}^{133}$Cs-${}^6$Li 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.

13 pages, 10 figures

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Cited by in corpus (9)

• Interactions mediated by atoms, photons, electrons, and excitons
• Quantum Monte Carlo and perturbative study of two-dimensional Bose-Fermi mixtures
• Observation of a Halo Trimer in an Ultracold Bose-Fermi Mixture
• Probing Goldstino excitation through the tunneling transport in a Bose-Fermi mixture with explicitly broken supersymmetry
• Boson-fermion pairing and condensation in two-dimensional Bose-Fermi mixtures
• Non-equilibrium dynamics and atom-pair coherence in strongly interacting Bose-Fermi mixtures
• Mechanical stability of resonant Bose-Fermi mixtures
• Exotic Superfluid with Emergent flux in a one-dimensional Bose-Fermi mixture
• Probing non-Gaussian correlations through entanglement generation in a many-body quantum system