Hysteretic squashed entanglement in many-body quantum systems

TL;DR

This paper introduces hysteretic squashed entanglement, a new measure for quantifying genuine quantum correlations in many-body systems, demonstrating its effectiveness in detecting topological entanglement and criticality.

Contribution

The paper proposes a novel entanglement measure, hysteretic squashed entanglement, with desirable properties and demonstrates its application in analyzing quantum correlations in many-body systems.

Findings

$T_{sq}$ effectively detects genuine quantum correlations.

$T_{sq}$ can quantify topological entanglement entropy in mixed states.

Application to transverse-field Ising model shows robustness of $T_{sq}$.

Abstract

Entanglement in many-body quantum systems is distributed across spatial regions, where its structure often dictates the information-processing capabilities of the state. Yet, characterizing the entanglement structure, especially for mixed states, remains a challenge. In this work, we propose hysteretic squashed entanglement $T_{sq}$, a conditional entanglement monotone that measures the genuine quantum correlations between two subregions, conditioned on a third region, in a many-body quantum state. $T_{sq}$ is upper bounded by the convex-roof extension of quantum conditional mutual information and exhibits several desirable properties like monogamy, convexity, asymptotic continuity, faithfulness, and additivity for tensor-product states. We study the conditional entanglement generation in a one-dimensional transverse-field Ising model under quench, where we show that $T_{sq}$ effectively squashes classical contributions and can detect genuine quantum correlations across both adjacent and long-range subsystems. We elucidate the utility of this measure as a robust quantifier of topological entanglement entropy for mixed states. This opens new operational resource-theoretic avenues for probing topological order and criticality.