Unified View of Quantum and Classical Correlations

TL;DR

This paper presents a unified framework for quantifying quantum and classical correlations in quantum states using relative entropy, introducing new definitions and applicable methods for multipartite systems.

Contribution

It introduces a unified approach to separate and quantify all correlations in quantum states, including entanglement, dissonance, and classical correlations, applicable to multipartite systems.

Findings

Dissonance can be present in pure multipartite states

Additivity relations between different correlations are investigated

All correlations can be analyzed on an equal footing using relative entropy

Abstract

We discuss the problem of the separation of total correlations in a given quantum state into entanglement, dissonance, and classical correlations using the concept of relative entropy as a distance measure of correlations. This allows us to put all correlations on an equal footing. Entanglement and dissonance, whose definition is introduced here, jointly belong to what is known as quantum discord. Our methods are completely applicable for multipartite systems of arbitrary dimensions. We investigate additivity relations between different correlations and show that dissonance may be present in pure multipartite states.