Pair density waves and vortices in an elongated two-component Fermi gas

TL;DR

This paper investigates vortex structures and phase transitions in an anisotropic two-component Fermi gas under magnetic fields, revealing instabilities towards pair density waves and vortex lattices, with detailed phase diagrams and density analyses.

Contribution

It provides the first detailed phase diagram and analysis of vortex and pair density structures in an anisotropic Fermi gas under magnetic fields, highlighting the transition to pair density waves.

Findings

Instabilities lead to pair density waves and vortex lattices.

Density and pair density structures resemble those in superfluid Bose gases.

Paired fraction depends on chemical potential and anisotropy.

Abstract

We study the vortex structures of a two-component Fermi gas experiencing a uniform effective magnetic field in an anisotropic trap that interpolates between quasi-one dimensional (1D) and quasi-two dimensional (2D). At a fixed chemical potential, reducing the anisotropy (or equivalently increasing the attractive interactions or increasing the magnetic field) leads to instabilities towards pair density waves, and vortex lattices. Reducing the chemical potential stabilizes the system. We calculate the phase diagram, and explore the density and pair density. The structures are similar to those predicted for superfluid Bose gases. We further calculate the paired fraction, showing how it depends on chemical potential and anisotropy.