Influence of an external magnetic field on the decoherence of a central spin coupled to an antiferromagnetic environment

TL;DR

This study investigates how an external magnetic field influences the decoherence of a central spin in an antiferromagnetic environment, revealing that decoherence peaks at the spin-flop transition and is affected by temperature.

Contribution

It provides a detailed analysis of the magnetic field's impact on decoherence dynamics using the spin wave approximation, highlighting the critical point effects.

Findings

Decoherence factor shows Gaussian decay influenced by magnetic field strength.

Decoherence peaks at the spin-flop transition point.

Environmental temperature also affects decoherence behavior.

Abstract

Using the spin wave approximation, we study the decoherence dynamics of a central spin coupled to an antiferromagnetic environment under the application of an external global magnetic field. The external magnetic field affects the decoherence process through its effect on the antiferromagnetic environment. It is shown explicitly that the decoherence factor which displays a Gaussian decay with time depends on the strength of the external magnetic field and the crystal anisotropy field in the antiferromagnetic environment. When the values of the external magnetic field is increased to the critical field point at which the spin-flop transition (a first-order quantum phase transition) happens in the antiferromagnetic environment, the decoherence of the central spin reaches its highest point. This result is consistent with several recent quantum phase transition witness studies. The influences of the environmental temperature on the decoherence behavior of the central spin are also investigated.