Asymmetry of bipartite quantum discord

TL;DR

This paper investigates the asymmetry of quantum discord in a two-spin system with dipole-dipole interaction, showing that temperature influences the degree of asymmetry, which is negligible at high temperatures but significant at lower temperatures.

Contribution

It provides a detailed analysis of how quantum discord asymmetry depends on temperature and magnetic field in a specific two-spin model, highlighting conditions for its significance.

Findings

Quantum discord asymmetry is negligible at high temperatures.

Asymmetry becomes significant as temperature decreases.

Dependence of discord asymmetry on Larmour frequencies is demonstrated.

Abstract

It is known from the analysis of the density matrix for bipartite systems that the quantum discord (as a measure of quantum correlations) depends on the particular subsystem chosen for the projective measurements. We study asymmetry of the discord in a simple physical model of two spin-1/2 particles with the dipole-dipole interaction governed by the XY Hamiltonian in the inhomogeneous magnetic field. The dependence of the above discord asymmetry on the Larmour frequencies at both T=0 (the ground state) and $T>0$ has been investigated. It is demonstrated, in particular, that the asymmetry is negligible for high temperatures but it may become significant with the decrease in temperature.