Population imbalance and pairing in the BCS-BEC crossover of three-component ultracold fermions

TL;DR

This paper explores the phase diagram and BCS-BEC crossover in a three-component ultracold Fermi gas with population imbalance and pairing, revealing a transition from BCS pairing to a molecular BEC state.

Contribution

It introduces a detailed analysis of the BCS-BEC crossover in a three-component system with population imbalance, including pairing fluctuations and a t-matrix approach.

Findings

Population imbalance occurs at low temperatures.

The system transitions from BCS pairing to a molecular BEC state.

Pairing fluctuations are significant in the crossover regime.

Abstract

We investigate the phase diagram and the BCS-BEC crossover of a homogeneous three-component ultracold Fermi gas with a U(3) invariant attractive interaction. We show that the system at sufficiently low temperatures exhibits population imbalance, as well as fermionic pairing. We describe the crossover in this system, connecting the weakly interacting BCS regime of the partially population-imbalanced fermion pairing state and the BEC limit with three weakly interacting species of molecules, including pairing fluctuations within a t-matrix calculation of the particle self-energies.