Bounds for Entanglement via an Extension of Strong Subadditivity of Entropy

Abstract

Let ρ 12 be a bipartite density matrix. We prove lower bounds for the entanglement of formation E f(ρ 12) and the squashed entanglement E sq(ρ 12) in terms of the conditional entropy S 12 - S 1 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. © 2012 The Author(s).