Dressed Feshbach molecules in the BEC-BCS crossover

TL;DR

This paper develops an RPA theoretical framework for the BEC-BCS crossover in atomic Fermi gases near a Feshbach resonance, accurately modeling two-body physics and comparing with recent experimental data.

Contribution

It introduces an RPA approach that exactly incorporates two-body atomic physics to analyze dressed molecules in the BEC-BCS crossover.

Findings

Calculated the probability Z of dressed molecules in the closed channel.

Determined the condensate density of dressed molecules across the crossover.

Compared theoretical predictions with recent experimental results.

Abstract

We present the RPA theory of the BEC-BCS crossover in an atomic Fermi gas near a Feshbach resonance that includes the relevant two-body atomic physics exactly. This allows us to determine the probability $Z$ for the dressed molecules in the Bose-Einstein condensate to be in the closed channel of the Feshbach resonance and to compare with the recent experiments of Partridge {\it et al.} [cond-mat/0505353] with $^{6}$Li. We determine for this extremely broad resonance also the condensate density of the dressed molecules throughout the BEC-BCS crossover.