Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 35: Poster 2
Q 35.36: Poster
Wednesday, March 14, 2012, 16:30–19:00, Poster.I+II
Optimized witnesses for Dicke- and W-states — •Marcel Bergmann1, Bastian Jungnitsch2, and Otfried Gühne1 — 1Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Straße 3, D-57068 Siegen — 2Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21A, A-6020 Innsbruck
Multiparticle entanglement is an important subject in quantum information theory. Recently, the number of particles that can be entangled experimentally using polarized photons or ion traps has been significantly enlarged. Due to this fact, criteria to decide the question whether a given multiparticle state is entangled or not have to be improved.
Our approach to this problem uses the notion of PPT mixtures [1] which form an approximation to the set of biseparable states. With this method, entanglement witnesses can be obtained in a natural manner via linear semidefinite programming. In our contribution, we will present analytical results for witnesses for W-states and Dicke states. This allows to overcome the limitations of convex optimization.
[1] B. Jungnitsch et al., Phys. Rev. Lett. 106, 190502 (2011).