Düsseldorf 2007 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 25: Quanteninformation (Verschränkung und Dekohärenz II)
Q 25.2: Talk
Tuesday, March 20, 2007, 14:30–14:45, 5L
Estimating entanglement measures in experiments — •Otfried Gühne1, Michael Reimpell2, and Reinhard Werner2 — 1Institut für Quantenoptik und Quanteninformation, A-6020 Innsbruck — 2Institut für Mathematische Physik, Technische Universität Braunschweig, D-38106 Braunschweig
The characterization of entanglement in experiments is an important problem in quantum information science. In this talk we present a method to estimate entanglement measures in experiments. We show how a lower bound on a generic entanglement measure can be derived from the measured expectation values of any finite collection of entanglement witnesses. Hence witness measurements are given a quantitative meaning without the need of further experimental data. We apply our results to a recent multi-photon experiment [M. Bourennane et al., Phys. Rev. Lett. 92, 087902 (2004)], giving bounds on the entanglement of formation and the geometric measure of entanglement in this experiment.