Symmetry breaking effects upon bipartite and multipartite entanglement in the XY model

TL;DR

This paper investigates how spontaneous symmetry breaking influences bipartite and multipartite entanglement in the ground state of the 1D XY model, revealing multipartite entanglement as a key indicator of quantum phase transitions.

Contribution

It explicitly accounts for spontaneous symmetry breaking to analyze its effects on entanglement near quantum critical points in the XY model.

Findings

Multipartite entanglement is affected by symmetry breaking near the critical point.

Bipartite entanglement is enhanced deep in the ferromagnetic phase but not near the critical point.

Multipartite entanglement better indicates long-range correlations in quantum phase transitions.

Abstract

We analyze the bipartite and multipartite entanglement for the ground state of the one-dimensional XY model in a transverse magnetic field in the thermodynamical limit. We explicitly take into account the spontaneous symmetry breaking in order to explore the relation between entanglement and quantum phase transitions. As a result we show that while both bipartite and multipartite entanglement can be enhanced by spontaneous symmetry breaking deep into the ferromagnetic phase, only the latter is affected by it in the vicinity of the critical point. This result adds to the evidence that multipartite, and not bipartite, entanglement is the fundamental indicator of long range correlations in quantum phase transitions.