Expansion dynamics of the Fulde-Ferrell-Larkin-Ovchinnikov state

TL;DR

This paper studies the expansion dynamics of a spin-imbalanced Fermi gas in the FFLO state, revealing that the unpaired particles' expansion velocity directly indicates the FFLO momentum, offering a clear experimental signature.

Contribution

It demonstrates a novel method to identify the FFLO state through expansion dynamics, linking the unpaired cloud velocity to the FFLO momentum.

Findings

Unpaired particle expansion velocity correlates with FFLO momentum.

The dynamics decompose into independent expansions of paired and unpaired particles.

Provides a simple experimental signature for FFLO state detection.

Abstract

We consider a two-component Fermi gas in the presence of spin imbalance, modeling the system in terms of a one-dimensional attractive Hubbard Hamiltonian initially in the presence of a confining trap potential. With the aid of the time-evolving block decimation method, we investigate the dynamics of the initial state when the trap is switched off. We show that the dynamics of a gas initially in the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state is decomposed into the independent expansion of two fluids, namely the paired and the unpaired particles. In particular, the expansion velocity of the unpaired cloud is shown to be directly related to the FFLO momentum. This provides an unambiguous signature of the FFLO state in a remarkably simple way.