Partial breakdown of quantum thermalization in a Hubbard-like model

TL;DR

This paper investigates the breakdown of quantum thermalization in a one-dimensional Hubbard-like model, revealing a potential new non-thermal phase called quantum disentangled liquid with unique entanglement properties.

Contribution

It demonstrates the emergence of a quantum disentangled liquid phase in a clean, disorder-free system through partial measurements affecting entanglement scaling.

Findings

Entanglement entropy transitions from volume to area law after partial measurement.

The model exhibits properties consistent with a quantum disentangled liquid.

Implications for the foundations of quantum statistical mechanics.

Abstract

We study the possible breakdown of quantum thermalization in a model of itinerant electrons on a one-dimensional chain without disorder, with both spin and charge degrees of freedom. The eigenstates of this model exhibit peculiar properties in the entanglement entropy, the apparent scaling of which is modified from a "volume law" to an "area law" after performing a partial, site-wise measurement on the system. These properties and others suggest that this model realizes a new, non-thermal phase of matter, known as a quantum disentangled liquid (QDL). The putative existence of this phase has striking implications for the foundations of quantum statistical mechanics.