Numerical modeling of the central spin problem using the spin coherent states P-representation

TL;DR

This paper introduces an efficient mean-field P-representation method to model the non-perturbative decoherence of a central spin caused by a large spin bath, enabling predictions of long-time decoherence dynamics.

Contribution

The work develops a novel P-representation based mean-field approach for simulating large quantum spin systems, capturing non-perturbative decoherence effects.

Findings

Successfully modeled systems with up to 16,000 bath spins

Predicted slow long-time decoherence behavior

Applicable to both longitudinal and transversal relaxation

Abstract

In this work, we consider decoherence of a central spin by a spin bath. In order to study the non-perturbative decoherence regimes, we develop an efficient mean-field-based method for modeling the spin-bath decoherence, based on the P-representation of the central spin density matrix. The method can be applied to longitudinal and transversal relaxation at different external fields. In particular, by modeling large-size quantum systems (up to 16000 bath spins), we make controlled predictions for the slow long-time decoherence of the central spin.