Alain Aspect, Jean Dalibard and Gérard Roger tested Bell inequalities using pairs of photons and rapidly changing polarization analyzers. An acousto-optical switch in each arm routed light toward one of two polarizers; switching near changed the effective setting on a timescale shorter than the photon transit time between the analyzers. The measured correlations violated the tested Bell inequality. These switches were driven at incommensurate frequencies, so their role should be distinguished from the independently randomized settings of later experiments.[ref]
A physicist researching quantum optics and the foundations of quantum mechanics.[ref]
Figure 1.
Portrait of Alain Aspect
. École polytechnique Université Paris-Saclay; Adem, existing portrait crop. CC BY-SA 2.0, via Wikimedia Commons. Source.

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Alain Aspect is a French physicist best known for his pioneering work in the field of quantum mechanics, particularly for his experiments involving entangled photons. His most famous experiments, conducted in the early 1980s, provided strong evidence for the violation of Bell's inequalities, which support the predictions of quantum mechanics over classical physics. Aspect's work has significant implications for the understanding of quantum entanglement and has contributed to the foundations of quantum information theory.
Alain Aspect by Ciro Santilli 40 Updated 2026-08-21
Video 1.
Alain Aspect in Quantum entanglement Documentary (1985)
Source. The moustache and broken English were already his trademarks back then!!! Also cool to get a glimpse of his lab, and good schematics of the experiment. TODO exact lab location? Documentary says in Paris, but where?