On correlations and mutual entropy in quantum composed systems
  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. 
Yuji Hirota, Dariusz Chru\'sci\'nski, Takashi Matsuoka and Masanori   Ohya
quant-ph