Detecting Initial System-Environment Correlations in Open Systems

TL;DR

This paper presents a method to detect initial correlations between a quantum system and its environment by measuring only the system, leveraging known interaction causes, which helps in error correction for open quantum systems.

Contribution

It introduces a technique to identify system-environment correlations using system measurements alone, assuming known interaction dynamics, applicable to realistic experimental conditions.

Findings

Detection is possible with known interaction causes.

Bounds are provided for certifying correlations.

Applicable to realistic experimental states.

Abstract

Correlations between a system and its environment lead to errors in an open quantum system. Detecting those correlations would be valuable for avoiding and/or correcting those errors. Here we show that we can detect correlations by only measuring the system itself if we know the cause of the interaction between the two, for example in the case of a dipole-dipole interaction. We investigate the unitary $U$ which is associated with the exchange Hamiltonian and examine the ability to detect initial correlations between a system and its environment for various types of initial states. The states we select are motivated by realistic experimental conditions and we provide bounds for when we can state with certainty that there are initial system-environment correlations given experimental data.