%0 Journal Article
%J Physical Review A
%D 2014
%T Best separable approximation of multipartite diagonal symmetric states
%A Quesada, Ruben
%A Sanpera, Anna
%X 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)]), that is, their unique convex decomposition into a separable part and an entangled part, with maximal weight of the separable part.
%B Physical Review A
%V 89
%8 5/2014
%N 5
%! Phys. Rev. A
%R 10.1103/PhysRevA.89.052319