Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

Q: Fachverband Quantenoptik und Photonik

Q 11: Quantum Information: Concepts and Methods II

Q 11.1: Vortrag

Montag, 8. März 2010, 16:30–16:45, E 214

Practical methods for witnessing genuine multi-qubit entanglement in the vicinity of symmetric states — •Geza Toth^1,2,3, Witlef Wieczorek^4,5, Roland Krischek^4,5, Nikolai Kiesel^4,5,6, Patrick Michelberger^4,5, and Harald Weinfurter^4,5 — ¹Theoretical Physics, The University of the Basque Country, E-48080 Bilbao, Spain — ²IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao, Spain — ³Research Institute for Solid State Physics and Optics, H-1525 Budapest, Hungary — ⁴Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany — ⁵Fakultät für Physik, Ludwig-Maximilians-Universität, D-80799 Garching, Germany — ⁶Institute for Quantum Optics and Quantum Information (IQOQI), A-1090 Vienna, Austria

We present general numerical methods to construct witness operators for entanglement detection and for the estimation of the fidelity. Our methods are applied to detecting entanglement in the vicinity of a six-qubit Dicke state with three excitations and also to further entangled symmetric states. All our witnesses are designed to keep the measurement effort small thus they are useful in many-qubit experiments. We present also general results on the efficient local decomposition of permutationally invariant operators, which makes it possible to measure projectors to symmetric states efficiently.