Hannover 2010 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 22: Quantum Effects: Entanglement and Decoherence II

Q 22.2: Talk

Wednesday, March 10, 2010, 10:45–11:00, A 310

Bell*s inequalities can be violated due to a trivial experimental loophole. Nonlocality is still unproven — •Karl Otto Greulich — Fritz Lipmann Institut Jena

Usually, optical experiments on the violation of Bell*s inequalities are theoretically explained with an atom as light source which emits two entangled photons. The experimental verification is, however, completely different. In essentially all real experiments, a down-converting birefringent crystal, pumped by a laser, is used. Thereby it is assumed that one can work, by sharp attenuation and spatial selection, in the *single photon* limit. This approach is risky, since there is growing evidence that it is extremely difficult, if not impossible, to safely achieve such a single photon limit from a multi atom light source. If in this respect a minimal error occurs, Bell*s inequalities can be violated in a very trivial way. Since this loophole so far never has been considered, a safe proof of nonlocality is still elusive.