title: Estimating entanglement measures in experiments.
abstract: 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 multiphoton experiment [M. Bourennane, Phys. Rev. Lett. 92, 087902 (2004)], giving bounds on the entanglement of formation and the geometric measure of entanglement in this experiment.
authors.affiliation: Institut für Quantenoptik und Quanteninformation, Osterreichische Akademie der Wissenschaften, A-6020 Innsbruck, Austria.
authors.forename: O
authors.initials: O
authors.lastname: Gühne
authors.forename: M
authors.initials: M
authors.lastname: Reimpell
authors.forename: R F
authors.initials: RF
authors.lastname: Werner