Nonlocal Correlation in Heisenberg Spin Models

TL;DR

This paper explores nonlocal quantum correlations in Heisenberg spin models, demonstrating that measurement-induced nonlocality and geometric quantum discord are equivalent and can exist without entanglement, influenced by spin interactions and magnetic fields.

Contribution

It reveals the equivalence of two nonlocal correlation measures and identifies conditions for non-entanglement-based nonlocality in Heisenberg spin systems.

Findings

Measurement-induced nonlocality and geometric quantum discord are identical.

Nonlocal correlation can exist without entanglement in the system.

External magnetic fields reduce non-classical correlations.

Abstract

In this paper we investigate the nonlocal correlation (beyond entanglement) captured by measurement induced nonlocality and geometric quantum discord for a pair of interacting spin-1/2 particles at thermal equilibrium. It is shown that both the measures are identical in measuring the correlation. We show the possibility of nonlocal correlation between the spins without entanglement, which ceases to exist only for the maximal mixture of product bases. We also observe that while interaction between the spins is responsible for the enhancement of correlation, this non-classicality decreases with the intervention of external magnetic field.