Pair correlations in the normal phase of an attractive Fermi gas

TL;DR

This paper provides a theoretical analysis of experimental measurements of fermion pair correlations in an attractive Fermi gas, using a self-consistent t-matrix approach that aligns well with observed data.

Contribution

It introduces an ab-initio self-consistent t-matrix calculation to explain pair correlations in the normal phase of an attractive Fermi gas, matching experimental results without adjustable parameters.

Findings

Good agreement between theory and experiment

Highlights the importance of pair-correlation functions

Supports the pseudogap and preformed-pair concepts

Abstract

In a recent paper [Phys. Rev. A 99, 053617 (2019)], the total number of fermion pairs in a spin-balanced two-component Fermi gas of $^6$Li atoms was experimentally probed in the normal phase above the superfluid critical temperature, in order to investigate the sectors of pseudogap and preformed-pair in the temperature-coupling phase diagram. Here, we present a theoretical account of these experimental results in terms of an ab-initio self-consistent $t$-matrix calculation, which emphasizes the role of the pair-correlation function between opposite-spin fermions at equilibrium. Good agreement is found between the available experimental data and the theoretical results obtained with no adjustable parameter.