Polaronic and dressed molecular states in orbital Feshbach resonances

TL;DR

This paper investigates impurity states in orbital Feshbach resonances, calculating polaron properties and the transition to molecules, revealing density-dependent shifts akin to narrow resonances.

Contribution

It introduces a detailed analysis of polaronic and molecular states in OFRs, including corrections to the transition point by considering particle-hole excitations.

Findings

Polaron effective mass and residue are calculated.

The polaron-molecule transition point shifts with density.

Including particle-hole excitations significantly alters the transition point.

Abstract

We consider the impurity problem in an orbital Feshbach resonance (OFR), with a single excited clock state $|e\uparrow\rangle$ atom immersed in a Fermi sea of electronic ground state $|g\downarrow\rangle$. We calculate the polaron effective mass and quasi-particle residue, as well as the polaron to molecule transition. By including one particle-hole excitation in the molecular state, we find significant correction to the transition point. This transition point moves toward the BCS side for increasing particle densities, which suggests that the corresponding many-body physics is similar to a narrow resonance.