Polaron to molecule transition in a strongly imbalanced Fermi gas

TL;DR

This paper investigates the transition from polaron to molecule in a highly imbalanced Fermi gas, determining the critical interaction strength and analyzing implications for the phase diagram, supported by variational and Monte Carlo methods.

Contribution

It provides a variational calculation of the polaron to molecule transition point, aligning with Monte Carlo results and experimental data, and discusses the transition's impact on the phase diagram.

Findings

Critical interaction strength for transition determined

Agreement with Monte Carlo and experimental results

Implications for phase diagram of imbalanced Fermi gases

Abstract

A single down spin Fermion with an attractive, zero range interaction with a Fermi sea of up-spin Fermions forms a polaronic quasiparticle. The associated quasiparticle weight vanishes beyond a critical strength of the attractive interaction, where a many-body bound state is formed. From a variational wavefunction in the molecular limit, we determine the critical value for the polaron to molecule transition. The value agrees well with the diagrammatic Monte Carlo results of Prokof'ev and Svistunov and is consistent with recent rf-spectroscopy measurements of the quasiparticle weight by Schirotzek et. al. In addition, we calculate the contact coefficient of the strongly imbalanced gas, using the adiabatic theorem of Tan and discuss the implications of the polaron to molecule transition for the phase diagram of the attractive Fermi gas at finite imbalance.