Entanglement in a first order quantum phase transition

TL;DR

This paper investigates the entanglement properties of a spin system undergoing a first order quantum phase transition, revealing a sudden change in entanglement at the critical point.

Contribution

It provides a detailed analysis of entanglement behavior across a first order quantum phase transition in an antiferromagnetic spin system.

Findings

Entanglement exhibits a discontinuous jump at the transition point.

The spectrum analysis confirms the nature of the phase transition.

Ground state properties are significantly affected by the transition.

Abstract

The phase diagram of spins 1/2 embedded in a magnetic field mutually interacting antiferromagnetically is determined. Contrary to the ferromagnetic case where a second order quantum phase transition occurs, a first order transition is obtained at zero field. The spectrum is computed for a large number of spins and allows one to study the ground state entanglement properties which displays a jump of its concurrence at the critical point.