Critical Temperature Curve in the BEC-BCS Crossover

TL;DR

This paper uses a new Monte Carlo method to accurately determine the universal transition temperature curve in the BEC-BCS crossover of two-component fermions, confirming key values at unitarity.

Contribution

It introduces a novel continuous-space-time diagrammatic determinant Monte Carlo method to study the BEC-BCS crossover and maps out the universal transition temperature curve.

Findings

Confirmed the transition temperature ratio at unitarity as 0.152(7).

Determined the universal $T_c/\epsilon_F$ curve across the crossover.

Identified the maximum of the transition temperature on the BEC side.

Abstract

The strongly-correlated regime of the BCS-BEC crossover can be realized by diluting a system of two-component fermions with a short-range attractive interaction. We investigate this system via a novel continuous-space-time diagrammatic determinant Monte Carlo method and determine the universal curve $T_c/\epsilon_F$ for the transition temperature between the normal and the superfluid states as a function of the scattering length with the maximum on the BEC side. At unitarity, we confirm that $T_c/\epsilon_F = 0.152(7)$.