Long-range multipartite entanglement close to a first order quantum phase transition

TL;DR

This paper investigates the structure of quantum correlations in strongly correlated spin systems, revealing long-range multipartite entanglement near phase transitions using analytical entanglement witnesses.

Contribution

It introduces a new analytical family of entanglement witnesses for detecting genuine multipartite entanglement in many-body systems.

Findings

Long-range multipartite entanglement appears near critical points.

Symmetry breaking correlates with the presence of multipartite entanglement.

The method is model-independent and applicable to various spin systems.

Abstract

We provide insight in the quantum correlations structure present in strongly correlated systems beyond the standard framework of bipartite entanglement. To this aim we first exploit rotationally invariant states as a test bed to detect genuine tripartite entanglement beyond the nearest-neighbor in spin-1/2 models. Then we construct in a closed analytical form a family of entanglement witnesses which provides a sufficient condition to determine if a state of a many-body system formed by an arbitrary number of spin-1/2 particles possesses genuine tripartite entanglement, independently of the details of the model. We illustrate our method by analyzing in detail the anisotropic XXZ spin chain close to its phase transitions, where we demonstrate the presence of long range multipartite entanglement near the critical point and the breaking of the symmetries associated to the quantum phase transition.