Excitonic states of an impurity in a Fermi gas

Abstract

We study excitonic states of an atomic impurity in a Fermi gas, i.e., bound states consisting of the impurity and a hole. Previous studies considered bound states of the impurity with particles from the Fermi sea where the holes only formed part of the particle-hole dressing. Within a two-channel model, we find that, for a wide range of parameters, excitonic states are not ground but metastable states. We further calculate the decay rates of the excitonic states to polaronic and dimeronic states and find they are long lived, scaling as ${\Gamma }_{\mathrm{Pol}}^{\mathrm{Exc}}\propto (\Delta \omega {)}^{5.5}$ and ${\Gamma }_{\mathrm{Dim}}^{\mathrm{Exc}}\propto (\Delta \omega {)}^4$. We also find that a new continuum of exciton-particle states should be considered alongside the previously known dimeron-hole continuum in spectroscopic measurements. Excitons must therefore be considered as a new ingredient in the study of metastable physics currently being explored experimentally.

published version

References in corpus (15)

• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Attractive and repulsive Fermi polarons in two dimensions
• The Equation of State of a Low-Temperature Fermi Gas with Tunable Interactions
• Fermi-Polaron: Diagrammatic Monte Carlo for Divergent Sign-Alternating Series
• Normal state of a polarized Fermi gas at unitarity
• Low-energy three-body dynamics in binary quantum gases
• Trimers, molecules and polarons in imbalanced atomic Fermi gases
• Polaron-molecule transitions in a two-dimensional Fermi gas
• Highly polarized Fermi gases in two dimensions
• Ground state of a tightly bound composite dimer immersed in a Fermi Sea
• Polarons and Molecules in a Two-Dimensional Fermi Gas
• Decay of polarons and molecules in a strongly polarized Fermi gas
• Molecule and polaron in a highly polarized two-dimensional Fermi gas with spin-orbit coupling
• The p-wave polaron
• Three-component Ultracold Fermi Gases with Spin-Orbit Coupling

Cited by in corpus (4)

• Universal many-body response of heavy impurities coupled to a Fermi sea
• Polaronic effects in one- and two-band quantum systems
• Bose polaron in spherical trap potentials: Spatial structure and quantum depletion
• Bose polaron in spherically symmetric trap potentials: Ground states with zero and lower angular momenta