Non-Equilibrium Mass Transport in the 1D Fermi-Hubbard Model

TL;DR

This paper studies how fermions expand in a 1D optical lattice, revealing dynamical phase separation and quantum distillation effects, with experimental and numerical insights into non-equilibrium mass transport.

Contribution

It provides new experimental and numerical evidence of dynamical phase separation and quantum distillation in the 1D Fermi-Hubbard model during sudden expansion.

Findings

Observation of phase separation between singlons and doublons.

Reduced interaction dependence of expansion speed for initial states without doublons.

Explanation of expansion dynamics based on interaction energy produced in the quench.

Abstract

We experimentally and numerically investigate the sudden expansion of fermions in a homogeneous one-dimensional optical lattice. For initial states with an appreciable amount of doublons, we observe a dynamical phase separation between rapidly expanding singlons and slow doublons remaining in the trap center, realizing the key aspect of fermionic quantum distillation in the strongly-interacting limit. For initial states without doublons, we find a reduced interaction dependence of the asymptotic expansion speed compared to bosons, which is explained by the interaction energy produced in the quench.