On correlations and mutual entropy in quantum composed systems

TL;DR

This paper investigates classical and quantum correlations using entropy-based measures, revealing that separable states can sometimes exhibit stronger correlations than entangled states, challenging common assumptions.

Contribution

It introduces an entropy-based correlation measure and demonstrates that separable states can have stronger correlations than entangled states, contrary to expectations.

Findings

Separable states can possess stronger correlations than entangled states.

Entropy-based measures can quantify correlations in quantum systems.

The study challenges the assumption that entanglement always correlates with stronger correlations.

Abstract

We study the correlations of classical and quantum systems from the information theoretical points of view. We analyze a simple measure of correlations based on entropy (such measure was already investigated as the degree of entanglement by Belavkin, Matsuoka and Ohya). Contrary to naive expectation, it is shown that separable state might possesses stronger correlation than an entangled state.