Unified view of quantum and classical correlations

Phys Rev Lett. 2010 Feb 26;104(8):080501. doi: 10.1103/PhysRevLett.104.080501. Epub 2010 Feb 22.

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.