Generalized information theoretic measure to discern the quantumness of correlations

TL;DR

This paper introduces a new measure of quantum correlations in bipartite states that accounts for measurement schemes, effectively distinguishing quantum from classical correlations and serving as an upper bound to entanglement.

Contribution

It proposes a generalized information-theoretic measure of quantumness that aligns with previous measures in special cases and accurately vanishes for separable states.

Findings

Quantumness measure coincides with previous measures in special cases.

It vanishes for all separable states.

Serves as an upper bound to the relative entropy of entanglement.

Abstract

A novel measure, quantumness of correlations is introduced here for bipartite states, by incorporating the required measurement scheme crucial in defining any such quantity. Quantumness coincides with the previously proposed measures in special cases and it vanishes for separable states - a feature not captured by the measures proposed earlier. It is found that an optimal generalized measurement on one of the parts leaves the overall state in its closest separable form, which shares the same marginal for the other part, implying that quantumness is non-zero for all entangled bipartite states and it serves as an upper bound to the relative entropy of entanglement.