Operational Discord Measure for Gaussian States with Gaussian Measurements

TL;DR

This paper introduces the operational Gaussian discord (OGD), a measure of nonclassical correlations in bipartite Gaussian states based on Gaussian measurements, with applications in quantum information protocols.

Contribution

It defines a new operational measure of quantum correlations for Gaussian states and demonstrates its significance in quantum information extraction tasks.

Findings

OGD can be explicitly calculated for standard form Gaussian states.

OGD provides operational insights into nonclassical correlations.

The measure is relevant for quantum protocols involving Gaussian states.

Abstract

We introduce an operational discord-type measure for quantifying nonclassical correlations in bipartite Gaussian states based on using Gaussian measurements. We refer to this measure as operational Gaussian discord (OGD). It is defined as the difference between the entropies of two conditional probability distributions associated to one subsystem, which are obtained by performing optimal local and joint Gaussian measurements. We demonstrate the operational significance of this measure in terms of a Gaussian quantum protocol for extracting maximal information about an encoded classical signal. As examples, we calculate OGD for several Gaussian states in the standard form.