The structural study of entanglement in multipartite systems is hindered by the lack of necessary and sufficient operational criteria able to discriminate among the various entanglement properties of a given mixed state. Here, we pursue a different route to the study of multipartite entanglement based on the closeness of a multipartite state to the set of separable ones. In particular, we analyze multipartite diagonal symmetric N-qubit states and provide the analytical expression for their best separable approximation (BSA, [Phys. Rev. Lett. 80, 2261 (1998)PRLTAO0031-900710.1103/PhysRevLett.80.2261]), that is, their unique convex decomposition into a separable part and an entangled part, with maximal weight of the separable part. © 2014 American Physical Society.
|Journal||Physical Review A - Atomic, Molecular, and Optical Physics|
|Publication status||Published - 15 May 2014|