Frankfurt 2006 – wissenschaftliches Programm

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SYSA: Quantum state analysis and estimation

SYSA 1: Quantum state analysis and estimation I

SYSA 1.2: Hauptvortrag

Dienstag, 14. März 2006, 11:00–11:30, HVI

Improved entanglement witnesses — •Otfried Gühne1, Wolfgang Dür1,2, Norbert Lütkenhaus3, and Geza Toth41Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, A-6020 Innsbruck — 2Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck — 3Quantum Information Theory Group, Institut für Theoretische Physik I, und Max-Planck Research Group, Institute of Optics, Information and Photonics, Universität Erlangen-Nürnberg, D-91058 Erlangen — 4Max-Planck-Institut für Quantenoptik, D-85748 Garching

Due to the rapid development of experimental techniques multiparticle entangled states of several ions or photons are now available. To confirm the success of an experiment, the analysis of the state has to verify that genuine multipartite entanglement was indeed produced. Entanglement witnesses are one of the most powerful tools for this task. These are linear inequalities for mean values of certain observables, where violation indicates entanglement.

In this talk we present several ideas to improve witnesses for special experimental situations. This can be done in several directions: First, one can reduce the required measurements, minimizing the experimentalists effort. Then, one can use new types of witnesses, which are more robust against noise. Also, one may apply local operations on the state, which do not change the entanglement properties. Finally, one may use nonlinear entanglement witnesses. We will also explain recent experiments, where some of these ideas have been used.

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DPG-Physik > DPG-Verhandlungen > 2006 > Frankfurt