Effect of initial system-environment correlations with spin environments

TL;DR

This paper investigates how initial correlations between a quantum system and its spin environment influence the system's dynamics, especially under strong coupling and low temperatures, revealing their significant role in single and two-qubit entanglement evolution.

Contribution

It provides an exact solution to a spin system model, highlighting the importance of initial correlations in open quantum system dynamics under various conditions.

Findings

Initial correlations can significantly affect system dynamics at strong coupling.

The impact of initial correlations varies with temperature and coupling strength.

Correlations influence entanglement dynamics between two spins.

Abstract

Understanding the dynamics of open quantum systems is a highly important task for the implementation of emerging quantum technologies. To make the problem tractable theoretically, it is common to neglect initial system-environment correlations. However, this assumption is questionable in situations where the system is interacting strongly with the environment. In particular, the system state preparation can then influence the dynamics of the system via the system-environment correlations. To gain insight into the effect of these correlations, we solve an exactly solvable model of a quantum spin interacting with a spin environment both with and without initial correlations for arbitrary system-environment coupling strengths. We show that the effect of the system state preparation may or may not be significant in the strong system-environment coupling regime at low temperatures. We also study the dynamics of the entanglement between two spins interacting with a common spin environment with and without initial system-environment correlations to demonstrate that the correlations can play a significant role in the dynamics of two-qubit systems as well.