Genuine quantum and classical correlations in multipartite systems
  Generalizing the quantifiers used to classify correlations in bipartite systems, we define genuine total, quantum, and classical correlations in multipartite systems. The measure we give is based on the use of relative entropy to quantify the "distance" between two density matrices. Moreover, we show that, for pure states of three qubits, both quantum and classical bipartite correlations obey a ladder ordering law fixed by two-body mutual informations, or, equivalently, by one-qubit entropies. 
Gian Luca Giorgi, Bruno Bellomo, Fernando Galve, Roberta Zambrini
quant-ph