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 formed only 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 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 a new ingredient in the study of metastable physics currently being explored experimentally.

Bose polaron in spherical trap potentials: Spatial structure and quantum depletion

“…The above experiments have also energized theoretical investigations, which include various issues of atomic polarons in zero-temperature media: quasiparticle properties of Bose polarons [20][21][22][23][24][25][26][27][28][29][30] and Fermi polarons [31][32][33][34][35][36][37][38][39][40][41][42][43][44], the self-localization of impurities in quasi-1D BEC media [45][46][47][48][49], polaronic spectral changes from a weak to strong coupling regime for attractive interactions [50][51][52][53][54], few-body physics around the unitarity limit [55][56][57][58][59], dynamics of the polaron formation [59][60][61][62], and open quantum dynamics [63][64][65]. Beside these 'conventional' atomic polarons, more e...…”

Polaronic effects in one- and two-band quantum systems

“…In ultracold quantum gases, evidence of polarons has been found in systems with trapped ions [36] or systems with a single ion immersed in a degenerate quantum gas [37][38][39][40][41][42][43]. On the other hand, the atomic polaron has also been studied both experimentally and theoretically in systems of imbalanced Bose-Fermi mixtures [44][45][46][47][48][49] and Fermi-Fermi mixtures [50][51][52][53][54][55][56][57]. In the particular case of a system with impurities immersed in a bosonic bath, these impurities couple to bosonic excitations.…”