Generalized entropic measures of quantum correlations

TL;DR

This paper introduces a unified framework for quantifying quantum correlations in bipartite systems using generalized entropic functions, capturing both entanglement and other non-classical correlations.

Contribution

It proposes a new measure based on generalized entropies and majorization, extending quantum correlation quantification beyond entanglement and quantum discord.

Findings

The measure reduces to generalized entanglement entropy for pure states.

It can detect non-classical correlations in separable mixed states.

Comparison with entanglement monotones demonstrates the measure's effectiveness.

Abstract

We propose a general measure of non-classical correlations for bipartite systems based on generalized entropic functions and majorization properties. Defined as the minimum information loss due to a local measurement, in the case of pure states it reduces to the generalized entanglement entropy, i.e., the generalized entropy of the reduced state. However, in the case of mixed states it can be non-zero in separable states, vanishing just for states diagonal in a general product basis, like the Quantum Discord. Simple quadratic measures of quantum correlations arise as a particular case of the present formalism. The minimum information loss due to a joint local measurement is also discussed. The evaluation of these measures in a few simple relevant cases is as well provided, together with comparison with the corresponding entanglement monotones.