Superfluidity in atomic Fermi gases

TL;DR

This paper reviews experimental progress on superfluidity in atomic Fermi gases, focusing on the BCS-BEC crossover regime where the interaction strength is tunable, and discusses a pairing fluctuation theory matching experimental data.

Contribution

It introduces an intuitive pairing fluctuation theory for the BCS-BEC crossover in atomic Fermi gases, aligning well with experimental observations.

Findings

Experimental evidence of superfluidity across the BCS-BEC crossover

Quantitative agreement of the pairing fluctuation theory with experiments

Insights into the nature of the superfluid phase in strongly interacting Fermi gases

Abstract

In a trapped atomic Fermi gas, one can tune continuously via a Feshbach resonance the effective pairing interaction between fermionic atoms from very weak to very strong. As a consequence, the low temperature superfluidity evolves continuously from the BCS type in the weak interaction limit to that of Bose-Einstein condensation in the strong pairing limit, exhibiting a BCS-BEC crossover. In this paper, we review recent experimental progress in atomic Fermi gases which elucidates the nature of the superfluid phase as the interaction is continuously tuned. Of particular interest is the intermediate or crossover regime where the $s$-wave scattering length diverges. We will present an intuitive pairing fluctuation theory, and show that this theory is in quantitative agreement with existing experiments in cold atomic Fermi gases.