Darmstadt 2008 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 41: Quanteninformation (Konzepte und Methoden III)
Q 41.4: Vortrag
Donnerstag, 13. März 2008, 14:45–15:00, 1B
Three-tangle for mixtures of generalized GHZ and generalized W states — •Christopher Eltschka1, Andreas Osterloh2, and Jens Siewert1 — 1Institut für theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany — 2Institut für theoretische Physik, Leibnitz Universität Hannover, D-30167 Hannover, Germany
The occurrence of entanglement in multipartite systems is one of the most important and distinctive features in quantum theory. While mixed state entanglement of two qubits is already well understood, for three qubits even for the simplest case of rank-2 mixed states, no general solution is known.
We give analytic expressions for the three-tangle and corresponding optimal decompositions for a class of mixed states consisting of a generalized GHZ and an orthogonal generalized W state. We derive a characteristiic structure of the three-tangle function which is independend of the choice of the generalized GHZ and W states to be mixed. Especially we identify the “zero simplex” of all states inside the corresponding Bloch sphere with zero three-tangle.
Moreover, as a special case we obtain a general solution for a family of states consisting of a generalized GHZ state and an orthogonal product state. For that case, we provide an analytic solution for all mixed states inside the Bloch sphere defined by those two states.