Scattering of two heavy Fermi polarons: resonances and quasibound states

Abstract

Impurities in a Fermi sea, or Fermi polarons, experience a Casimir interaction induced by quantum fluctuations of the medium. When there is short-range attraction between impurities and fermions, also the induced interaction between two impurities is strongly attractive at short distance and oscillates in space for larger distances. We theoretically investigate the scattering properties and compute the scattering phase shifts and scattering lengths between two heavy impurities in an ideal Fermi gas at zero temperature. While the induced interaction between impurities is weakly attractive for weak impurity-medium interactions, we find that impurities strongly and attractively interacting with the medium exhibit resonances in the induced scattering with a sign change of the induced scattering length and even strong repulsion. These resonances occur whenever a three-body Efimov bound state appears at the continuum threshold. At energies above the continuum threshold, we find that the Efimov state in medium can turn into a quasibound state with a finite decay width.

7 pages, 6 figures; published version

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• Universal van der Waals Force Between Heavy Polarons in Superfluids
• Interactions mediated by atoms, photons, electrons, and excitons
• Three-body crossover from a Cooper triple to bound trimer state in three-component Fermi gases near a triatomic resonance
• Medium-induced Interaction Between Impurities in a Bose-Einstein Condensate
• Strongly interacting Bose-Fermi mixture: mediated interaction, phase diagram and sound propagation
• Medium-induced bosonic clusters in a Bose-Fermi mixture: Towards simulating cluster formations in neutron-rich matter
• Competing few-body correlations in ultracold Fermi polarons
• Extracting non-local inter-polaron interactions from collisional dynamics
• Impurity with a resonance in the vicinity of the Fermi energy
• Self-stabilized Bose polarons
• Effective pair interaction between impurity particles induced by a dense Fermi gas
• Complex-valued in-medium potential between heavy impurities in ultracold atoms