Universal dynamics of quantum spin decoherence in a spin bath

TL;DR

This paper reveals that the decoherence dynamics of a localized electron in a nuclear spin bath follow a universal pattern, depending on a single initial state parameter, applicable even for small systems and aiding experimental comparisons.

Contribution

It establishes the universal behavior of spin decoherence dynamics in arbitrary nuclear spin baths, dependent on a single initial condition parameter, regardless of system size.

Findings

Universal spin relaxation and dephasing behaviors identified.

Dynamics depend on a single initial state parameter.

Numerical results support theoretical predictions.

Abstract

We systematically investigate the universal spin decoherence dynamics of a localized electron in an arbitrary nuclear spin bath, which can be even far away from equilibrium due to the weak nuclear-lattice interaction. We show that the electron spin relaxation dynamics (as well as spin pure dephasing and Hahn echo decay) can {\it always} have a universal behavior as long as the initial state is composed of a sufficiently large amount of spin eigenstates. For a given system, the pattern of the universal dynamics depends on the complicated initial condition only via a {\it single} parameter, which measures the amount of phase coherence between different spin eigenstates in the initial state. Our results apply even when the number of the involved nuclei is not large, and therefore provide a solid foundation in the comparison of theoretical/numerical results with the experimental measurement. As an example, we also show numerical results for systems of noninteracting spin bath in zero magnetic field regime, and discuss the features of universal decoherent dynamics.