Sound propagation in a Bose-Fermi mixture: from weak to strong interactions

Abstract

Particle-like excitations, or quasi-particles, emerging from interacting fermionic and bosonic quantum fields underlie many intriguing quantum phenomena in high energy and condensed matter systems. Computation of the properties of these excitations is frequently intractable in the strong interaction regime. Quantum degenerate Bose-Fermi mixtures offer promising prospects to elucidate the physics of such quasi-particles. In this work, we investigate phonon propagation in an atomic Bose-Einstein condensate immersed in a degenerate Fermi gas with interspecies scattering length $a_{\text{BF}}$ tuned by a Feshbach resonance. We observe sound mode softening with moderate attractive interactions. For even greater attraction, surprisingly, stable sound propagation re-emerges and persists across the resonance. The stability of phonons with resonant interactions opens up opportunities to investigate novel Bose-Fermi liquids and fermionic pairing in the strong interaction regime.

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Cited by in corpus (17)

• Interactions mediated by atoms, photons, electrons, and excitons
• Strongly interacting Bose-Fermi mixture: mediated interaction, phase diagram and sound propagation
• Collective flow of fermionic impurities immersed in a Bose-Einstein Condensate
• 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
• Resonance triplet dynamics in the quenched unitary Bose gas
• Boson-fermion pairing and condensation in two-dimensional Bose-Fermi mixtures
• An experimental platform for studying the heteronuclear Efimov effect with an ultracold mixture of ${}^6$Li and ${}^{133}$Cs atoms
• Mediated Interactions and Damping Effects in Superfluid Mixtures of Bose and Fermi Gases
• Non-equilibrium dynamics and atom-pair coherence in strongly interacting Bose-Fermi mixtures
• Tunable Fujita-Miyazawa-Type Three-Body Force in Ultracold Atoms
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