Detecting nonclassical system-environment correlations by local operations

TL;DR

This paper presents a local operation-based method to detect nonclassical correlations in open quantum systems, using a witness derived from the Hilbert-Schmidt distance that relates to quantum discord and concurrence.

Contribution

It introduces a novel local dephasing map approach to identify quantum correlations, providing an experimentally accessible witness and linking it to quantum discord and concurrence.

Findings

The witness effectively detects nonclassical correlations.

Expectation value relates to quantum discord and concurrence.

Method applies to generic complex quantum systems.

Abstract

We develop a general strategy for the detection of nonclassical system-environment correlations in the initial states of an open quantum system. The method employs a dephasing map which operates locally on the open system and leads to an experimentally accessible witness for genuine quantum correlations, measuring the Hilbert-Schmidt distance between pairs of open system states. We further derive the expectation value of the witness for various random matrix ensembles modeling generic features of complex quantum systems. This expectation value is shown to be proportional to a measure for the quantum discord which reduces to the concurrence for pure initial states.