Superfluid Expansion of a Strongly Interacting Fermi Gas

TL;DR

This paper investigates the expansion dynamics of a rotating superfluid Fermi gas, demonstrating that superfluid pairs persist during expansion to very low densities, thus extending the understanding of fermionic superfluidity.

Contribution

It provides experimental evidence of superfluid flow at unprecedented low densities, expanding the known regime of fermionic superfluidity during expansion.

Findings

Superfluid pairs survive during expansion until a critical density

Vortices distinguish superfluid and normal components

Superfluidity observed at densities an order of magnitude lower than before

Abstract

We study the expansion of a rotating, superfluid Fermi gas. The presence and absence of vortices in the rotating gas is used to distinguish superfluid and normal parts of the expanding cloud. We find that the superfluid pairs survive during the expansion until the density decreases below a critical value. Our observation of superfluid flow at this point extends the range where fermionic superfluidity has been studied to densities of 1.2 10^{11} cm^{-3}, about an order of magnitude lower than any previous study.