Hamburg 2009 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 64: Quanteneffekte: Verschränkung
Q 64.1: Talk
Friday, March 6, 2009, 14:00–14:15, VMP 6 HS-D
Violation of local realism with freedom of choice — •Thomas Scheidl1,2, Rupert Ursin1,2, Johannes Kofler1,2, Sven Ramelow1,2, Xiaosong Ma1,2, Thomas Herbst1,2, Lothar Ratschbacher1,2, Alessandro Fedrizzi1,2, Nathan Langford1,2, Thomas Jennewein1,2, and Anton Zeilinger1,2 — 1Faculty for Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria — 2Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
The predictions of quantum mechanics can be in striking contradiction with local realism if entanglement exists between distant systems. Bell's theorem shows that local realistic theories place a strong restriction on observable correlations between different systems in experiments, giving rise to Bell's inequality. This allows an experimental test of whether nature itself agrees with local realism or quantum mechanics. To derive his inequality, Bell made three assumptions: realism, locality, and freedom of choice. In experimental Bell test, there may be "loopholes" which allow observed violations to still be explained by local realistic theories. Many Bell tests so far have closed individual loopholes, specifically the locality loophole and the fair-sampling loophole. However, the loophole related to Bell's freedom-of-choice assumption was not yet addressed experimentally. Here we report an experiment using entangled photons, which for the first time closes this loophole and simultaneously closes the locality loophole. It is also the first to close two of the three crucial loopholes at the same time.