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Accueil du site > Séminaires > Séminaires 2010 > Entanglement of mixed three-qubit states with GHZ and W state components

Mardi 23 novembre — 14:00

Entanglement of mixed three-qubit states with GHZ and W state components

Jens Siewert (Université de Bilbao)

par Pierre Pujol - 23 novembre 2010

Characterizing entanglement of multipartite mixed states is a fundamental issue in quantum information for which there is no general theory yet. We have investigated the entanglement properties of mixed three-qubit states composed of a GHZ state and a W state orthogonal to the former. In particular we have found the convex roofs for the three-tangle, and we have analyzed the Coffman-Kundu-Wootters inequality for this family of mixed states. The results reveal intriguing differences compared to the properties of two-qubit mixed states. In particular we find that, the well-known monogamy of entanglement can be lifted for mixed states. Moreover, we have found an analytical criterion to decide whether or not an arbitrary rank-2 N-qubit state contains finite k-tangle (measured by a given polynomial invariant).