Quantum discord in the central spin model

TL;DR

This paper analytically investigates the dynamics of quantum discord in a central spin model during free induction decay and spin echo, revealing how quantum correlations evolve and depend on experimental conditions.

Contribution

It provides analytical formulas for quantum discord evolution in the central spin model under high-temperature approximation, covering both FID and spin echo scenarios.

Findings

Quantum discord exhibits different time dependences in FID and spin echo.

Discord in spin echo strongly depends on time at short times.

Quantum discord tends to zero with decreasing magnetic field in spin echo.

Abstract

The quantum properties of dynamic correlations in a system of an electron spin surrounded by nuclear spins under the conditions of free induction decay (FID) and spin echo have been studied. Analytical results for the time evolution of mutual information, classical part of correlations, and quantum part characterized by quantum discord have been obtained within the central spin model in the high-temperature approximation. The same formulas describe the quantum discord in both the FID and the spin echo although the forms of the dependences are different because of difference in the parameters entering into the formulas. Discord of the spin echo compared with the FID has a strong dependence on time at short times, and it tends to zero with decreasing of the magnetic field, whereas in the case of the FID it reaches a plateau.