Quantum phase transitions in fully connected spin models: an entanglement perspective

TL;DR

This paper investigates quantum phase transitions in fully connected spin models by analyzing ground-state entanglement measures, revealing that discontinuous transitions typically cause abrupt changes in entanglement, with some exceptions.

Contribution

It provides a detailed analysis of entanglement behavior across different types of quantum phase transitions in fully connected spin models, highlighting new insights into entanglement dynamics.

Findings

Discontinuous transitions often cause jumps in entanglement measures.

Some models show continuous entanglement changes despite phase transitions.

Different entanglement measures exhibit similar qualitative behaviors.

Abstract

We consider a set of fully connected spins models that display first- or second-order transitions and for which we compute the ground-state entanglement in the thermodynamical limit. We analyze several entanglement measures (concurrence, R\'enyi entropy, and negativity), and show that, in general, discontinuous transitions lead to a jump of these quantities at the transition point. Interestingly, we also find examples where this is not the case.