Herring-Flicker coupling and thermal quantum correlations in bipartite system

TL;DR

This paper investigates how thermal quantum correlations, including quantum discord and entanglement, behave in a bipartite system with Herring-Flicker coupling under external magnetic fields, revealing long-lasting discord even when entanglement vanishes.

Contribution

It introduces the study of quantum correlations in a bipartite system with Herring-Flicker coupling, highlighting the long-term behavior of quantum discord compared to entanglement.

Findings

Quantum discord persists longer than entanglement over coupling distance R.

Entanglement can vanish while quantum discord remains.

Quantum correlations can be tuned via distance, temperature, and magnetic field.

Abstract

In this letter we study thermal quantum correlations as quantum discord and entanglement in bipartite system imposed by external magnetic field with Herring-Flicker coupling ie. $J(R)=1.642 e^{-2 R} R^{5/2}+O(R^{2}e^{-2R})$. The Herring-Flicker coupling strength is the function of $R$, which is the distance between spins and systems carry XXX Heisenberg interaction. By tuning the coupling distance $R$, temperature and magnetic field quantum correlations can be scaled in the bipartite system. We find the long sustainable behaviour of quantum discord in comparison to entanglement over the coupling distance $R$. We also investigate the situations, where entanglement totally dies but quantum discord exist in the system. The present findings in the letter may be useful for designing quantum wires, data bus, solid state gates and quantum processors.