Spin decoherence due to Fluctuating Fields

TL;DR

This paper provides an analytical study of spin decoherence caused by various types of magnetic field fluctuations, showing how deterministic fields can suppress decoherence and offering insights into noise effects on spin dynamics.

Contribution

It presents exact analytical solutions for spin expectation values under different noise models, revealing how deterministic fields can control decoherence.

Findings

Decoherence is caused by magnetic field fluctuations.

Deterministic magnetic fields can suppress spin decoherence.

Analytical solutions are derived for Gaussian white, colored, and telegraph noise.

Abstract

The dynamics of a spin in the presence of a deterministic and a fluctuating magnetic field is solved for analytically to obtain the averaged value of the spin as a function of time for various kinds of fluctuations (noise). Specifically, analytic results are obtained for the time dependence of the expectation value of the spin, averaged over fluctuations, for Gaussian white noise and Guassian colored noise, as well as non-Gaussian telegraph noise. Fluctuations cause the decay of the average spin vector (decoherence). For noise with finite temporal correlation time, a deterministic component of the field can suppress decoherence of the spin component along the field. Hence, decoherence can be manipulated by controlling the deterministic magnetic field. A simple universal physical picture emerges which explains the mechanism of the suppression of the decay.