Expansion of 1D polarized superfluids: The FFLO state reveals itself

TL;DR

This paper demonstrates that during expansion, a 1D polarized Fermi gas exhibits spin density modulations directly linked to the FFLO state, providing clear experimental evidence for this elusive superfluid phase.

Contribution

It combines mean-field and exact numerical methods to show how FFLO signatures emerge during expansion, offering a new way to detect this state.

Findings

Spin density modulations develop during expansion

Modulations are directly related to the FFLO state

Results provide evidence for the FFLO phase in 1D gases

Abstract

We study the expansion dynamics of a one dimensional polarized Fermi gas after sudden release from confinement using both the mean-field Bogoliubov-de Gennes and the numerically exact Time-Evolving Block Decimation methods. Our results show that experimentally observable spin density modulations directly related to the presence of a Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state develop during the expansion of the cloud, providing incontrovertible evidence of this long-sought state.