Resonance theory of the crossover from Bardeen-Cooper-Schrieffer superfluidity to Bose-Einstein condensation in a dilute Fermi gas

TL;DR

This paper develops a theoretical framework to describe the continuous transition from BCS superfluidity to Bose-Einstein condensation in a fermionic gas near a Feshbach resonance, highlighting high critical temperatures.

Contribution

It introduces a resonance Hamiltonian and a functional method to unify the BCS-BEC crossover description, consistent with microscopic scattering physics.

Findings

High critical temperature comparable to Fermi temperature.

Continuous crossover from BCS to BEC superfluidity.

Theoretical model aligns with microscopic scattering physics.

Abstract

We present a description of the behavior of a superfluid gas of fermions in the presence of a Feshbach resonance over the complete range of magnetic field detunings. Starting from a resonance Hamiltonian, we exploit a functional method to describe the continuous behavior from Bardeen-Cooper-Schrieffer to Bose-Einstein condensation type superfluidity. Our results show an ability for a resonance system to exhibit a high critical temperature comparable to the Fermi temperature. The results are derived in a manner that is shown to be consistent with the underlying microscopic scattering physics.