Entanglement in the 1D extended anisotropic Heisenberg model

TL;DR

This paper investigates how quantum entanglement, measured by concurrence, changes during phase transitions in a 1D extended anisotropic Heisenberg model using exact numerical methods.

Contribution

It provides the first detailed analysis of entanglement behavior across quantum phase transitions in this specific spin model.

Findings

Quantum phase transitions are accompanied by qualitative changes in entanglement.

Entanglement measures can signal different phases in the model.

Finite-size scaling confirms the robustness of entanglement changes.

Abstract

We present a study of entanglement in the case of the 1D extended anisotropic Heisenberg model. We investigate two quantum phase transitions (QPTs) within the previously found ergodicity phase diagram [E. Plekhanov, A. Avella, and F. Mancini Phys. Rev. B \textbf{74}, 115120 (2006)]. Our calculations are done by means of the numerically exact Lanczos method at T=0, followed by a finite-size scaling. As a measure of entanglement we use the concurrence for two spins out of the system. We conclude from our studies that these QPTs are accompanied by a qualitative entanglement change.