A proposal for realising quantum scars in the tilted 1D Fermi-Hubbard model

TL;DR

This paper demonstrates the existence of quantum many-body scars in a tilted 1D Fermi-Hubbard model, revealing a novel mechanism and highlighting the system's potential for studying ergodicity breaking phenomena.

Contribution

It introduces a new instance of quantum many-body scars in the Fermi-Hubbard model and uncovers a unique mechanism involving a weakly connected subgraph.

Findings

Quantum scars observed at $U\approx \Delta \gg J$ and $ u=1$

Scarring phenomenology similar to Rydberg chains

Distinct mechanism involving a free spin-1 paramagnet subgraph

Abstract

Motivated by recent observations of ergodicity breaking due to Hilbert space fragmentation in 1D Fermi-Hubbard chains with a tilted potential [Scherg et al., arXiv:2010.12965], we show that the same system also hosts quantum many-body scars in a regime $U\approx \Delta \gg J$ at electronic filling factor $\nu=1$. We numerically demonstrate that the scarring phenomenology in this model is similar to other known realisations such as Rydberg atom chains, including persistent dynamical revivals and ergodicity-breaking many-body eigenstates. At the same time, we show that the mechanism of scarring in the Fermi-Hubbard model is different from other examples in the literature: the scars originate from a subgraph, representing a free spin-1 paramagnet, which is weakly connected to the rest of the Hamiltonian's adjacency graph. Our work demonstrates that correlated fermions in tilted optical lattices provide a platform for understanding the interplay of many-body scarring and other forms of ergodicity breaking, such as localisation and Hilbert space fragmentation.