Quantum-disentangled liquid in the half-filled Hubbard model

TL;DR

This paper explores the existence of quantum disentangled liquid states in the half-filled Hubbard model, showing that certain eigenstates display non-thermal entanglement properties in one and higher dimensions.

Contribution

It demonstrates the presence of QDL states in the Hubbard model using integrability and strong coupling methods, highlighting their atypical entropy characteristics.

Findings

QDL states exist at finite energy densities in 1D Hubbard model.

Thermal states at large U exhibit a weaker QDL property.

QDL behavior extends to higher dimensions in the Hubbard model.

Abstract

We investigate the existence of quantum disentangled liquid (QDL) states in the half-filled Hubbard model on bipartite lattices. In the one dimensional case we employ a combination of integrability and strong coupling expansion methods to argue that there are indeed finite energy-density eigenstates that exhibit QDL behaviour in the sense of J. Stat. Mech. P10010 (2014). The states exhibiting the QDL property are atypical in the sense that while their entropy density is non-zero, it is smaller than that of thermal states at the same energy density. We argue that for U >> t these latter thermal states exhibit a weaker form of the QDL property, which carries over to the higher dimensional case.