Swallowtail Structure in Fermi Superfluids with Periodically Modulated Interactions

TL;DR

This paper explores the emergence of swallowtail energy structures in a quasi-one-dimensional Fermi superfluid with spatially modulated interactions, revealing rich phase behavior and potential experimental signatures.

Contribution

It demonstrates the formation and disappearance of swallowtail structures in the energy spectrum due to interaction modulation and nonlinearity, providing new insights into phase transitions in Fermi superfluids.

Findings

Swallowtail structures appear under certain parameters.

Disappearance of swallowtail structures with tuning interactions.

Spatial distributions of order parameter and density vary with parameters.

Abstract

We study the superfluid flow in a quasi-one-dimensional Fermi gas with spatially modulated interactions induced by an optical Feshbach resonance. Due to the competition between the periodicity of the modulated interaction and the nonlinearity of the background interaction, an interesting swallowtail structure emerges in the energy spectrum under appropriate parameters. As the interaction strengths are tuned, the swallowtail structure may disappear, giving rise to various different states on a rich phase diagram. We investigate the spatial distribution of the order parameter and the particle density under various parameters, which are useful for the experimental detection of the interesting phases in these systems.