Short-Time Decoherence for General System-Environment Interactions

TL;DR

This paper develops a short-time approximation method to evaluate the initial decoherence in quantum systems with general non-Hermitian interactions, especially relevant at low temperatures and for quantum computing applications.

Contribution

It introduces a novel short-time decoherence approximation for general system-environment interactions involving non-Hermitian operators, complementing existing Markovian approaches.

Findings

Applicable to low-temperature quantum systems

Detailed analysis of spin-boson coupling via $\sigma_-$

Provides a framework for evaluating decoherence onset

Abstract

Short time approximation is developed for system-environmental bath mode interactions involving a general non-Hermitian system operator $\Lambda$, and its conjugate, $\Lambda^\dagger$, in order to evaluate onset of decoherence at low temperatures in quantum systems interacting with environment. The developed approach is complementary to Markovian approximations and appropriate for evaluation of quantum computing schemes. Example of a spin system coupled to a bosonic heat bath via $\Lambda \propto \sigma_-$ is worked out in detail.