Bounds for Entanglement via an Extension of Strong Subadditivity of   Entropy
  We prove lower bounds for the entanglement of formation and the squashed entanglement for any a bipartite density matrix in terms of the conditional entropy of the bipartite state with respect to either of its partial traces, and prove that these bounds are sharp by constructing a new class of states whose entanglements can be computed, and for which the bounds are saturated. 
Eric A. Carlen and Elliott H. Lieb
quant-ph math-ph math.MP math.OA