Correlation measures in bipartite states and entanglement   irreversibility
  We derive quantitative relations among several naturally defined measures of classical and nonclassical correlations in a bipartite quantum state. We also obtain an upper bound of entanglement irreversibility and a sufficient condition for reversible entanglement. The additivity of entanglement of formation is directly related to the additivity of quantum discord as well as a certain measure of classical correlation. 
Shengjun Wu
quant-ph math-ph math.MP