Characterization of separable states and entanglement witnesses
Document type:
Zeitschriftenaufsatz
Author(s):
Lewenstein, M.; Kraus, B.; Horodecki, P.; Cirac, J. I.
Abstract:
We provide a canonical form of mixed states in bipartite quantum systems in terms of a convex combination of a separable state and a so-called edge state. We construct entanglement witnesses for all edge states, which allows us to introduce a canonical form of nondecomposable entanglement witnesses and the corresponding positive maps. We also present a nontrivial necessary condition for entanglement witnesses and positive maps to be extremal.