Quantum correlations in a system of nuclear s=1/2 spins in a strong magnetic field

TL;DR

This paper investigates quantum correlations, including entanglement and discord, in a system of nuclear spin-1/2 particles within a nanopore, revealing temperature-dependent behaviors and dynamic flickering of quantum discord.

Contribution

It provides analytical expressions for concurrence in centrosymmetric states and explores the dynamics of quantum discord, including geometric discord, in a novel physical system.

Findings

Quantum entanglement depends on temperature and number of spins.

Quantum discord exhibits flickering behavior and can vanish periodically.

Analytic formula for concurrence in centrosymmetric density matrices is derived.

Abstract

Entanglement and quantum discord for a pair of nuclear spins $s=1/2$ in a nanopore filled with a gas of spin-carrying molecules (atoms) are studied. The correlation functions describing dynamics of dipolar coupled spins in a nanopore are found. The dependence of spin-pair entanglement on the temperature and the number of spins is obtained from the reduced density matrix, which is centrosymmetric (CS). An analytic expression for the concurrence is obtained for an arbitrary CS density matrix. It is shown that the quantum discord as a measure of quantum correlations attains a significant value at low temperatures. It is shown also that the discord in the considered model has "flickering" character and disappears periodically in the course of the time evolution of the system. The geometric discord is studied for arbitrary $4\times 4$ CS density matrices.