Monte Carlo study of a Fermi gas with infinite scattering length

TL;DR

This paper applies and improves Monte Carlo worm algorithm techniques to study the properties of a strongly interacting Fermi gas at unitarity, including critical temperature calculations for balanced and imbalanced cases.

Contribution

The authors implement and test a Monte Carlo worm algorithm for Fermi gases, introducing a modification to enhance efficiency and applying it to compute critical temperatures.

Findings

Modified algorithm reduces autocorrelations.

Calculated critical temperature for balanced Fermi gas.

Extended method to imbalanced Fermi gas cases.

Abstract

The Fermi gas at unitarity is a particularly interesting system of cold atoms, being dilute and strongly interacting at the same time. It can be studied non-perturbatively with Monte Carlo methods, like the recently developed worm algorithm. We discuss our implementation and tests of this algorithm and suggest a modification that increases its efficiency by reducing autocorrelations. We then show how the worm algorithm can be applied to calculate the critical temperature of an imbalanced Fermi gas (unequal number of fermions in the two spin components). We finally present some results obtained with the modified algorithm, in the balanced as well as in the imbalanced case.