Inherent quantum resources in stationary spin chains

TL;DR

This paper reveals that stationary eigenstates of certain spin chains inherently contain many-body Bell correlations, which are robust against disorder and can vary discretely with magnetization, challenging the notion that such correlations only arise dynamically.

Contribution

It demonstrates that many-body Bell correlations are intrinsic to eigenstates of specific spin models, not just generated through dynamical protocols.

Findings

Eigenstates of the Lipkin-Meshkov-Glick model exhibit many-body Bell correlations.

Bell correlations can take quantized, discontinuous values with changing magnetization.

These correlations persist despite the presence of disorder.

Abstract

The standard way to generate many-body quantum correlations is via a dynamical protocol: an initial product state is transformed by interactions that generate non-classical correlations at later times. Here, we show that many-body Bell correlations are inherently present in the eigenstates of a variety of spin-1/2 chains. In particular, we show that the eigenstates and thermal states of the collective Lipkin-Meshkov-Glick model possess many-body Bell correlations. We demonstrate that the Bell correlations can take on quantized values that change discontinuously with variations in the total magnetization. Finally, we show that these many-body Bell correlations persist even in the presence of both diagonal and off-diagonal disorder.