Nonequilibrium Mass Transport in the 1D Fermi-Hubbard Model

We report on the results of a combined experimental and numerical study of nonequilibrium dynamics of ultracold fermions in a 1d lattice induced by quenching the trapping potential to zero [1]. This leads to an expansion of the cloud in a homogeneous lattice under the influence of interactions. For initial states with a significant admixture of doublons in a sea of singlons, we observe a dynamical demixing of fast expanding singlons from doublons that remain in the center of the system. We interpret this as evidence for fermionic quantum distillation [2]. For initial product states of one fermion per site and random spin orientations, we study the asymptotic expansion velocity. Compared to bosons [3], these velocities depend only very weakly on the interaction strength. We explain this observation by the fact that the Pauli principle significantly limits the amount of interaction energy that can be generated for fermions as compared to bosons.

[1] S. Scherg et al., PRL 121, 130402 (2018)
[2] F. Heidrich-Meisner et al., PRA 80, 041603 (2009)
[3] J. P. Ronzheimer et al., PRL 110, 205301 (2013)