Expansion of 1D polarized superfluids: the Fulde-Ferrell-Larkin-Ovchinnikov state reveals itself.

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.