Crossover temperature of Bose-Einstein condensation in an atomic Fermi gas

TL;DR

This paper investigates the crossover temperature in an atomic Fermi gas near a Feshbach resonance, showing it occurs at positive detuning and matching experimental observations, thus clarifying the nature of the BEC-BCS crossover.

Contribution

It identifies the crossover point at positive detuning and provides a theoretical determination of the crossover temperature aligning with experimental data.

Findings

Crossover occurs at positive detuning.

Crossover temperature matches experimental results.

Theoretical model agrees with observed data.

Abstract

We show that in an atomic Fermi gas near a Feshbach resonance the crossover between a Bose-Einstein condensate of diatomic molecules and a Bose-Einstein condensate of Cooper pairs occurs at positive detuning, i.e., when the molecular energy level lies in the two-atom continuum. We determine the crossover temperature as a function of the applied magnetic field and find excellent agreement with the experiment of Regal et al. [Phys. Rev. Lett. 92, 040403 (2004)] that has recently observed this crossover temperature.