Who led the 1982 experiment that confirmed violation of Bell's inequalities?

Alain Aspect led the 1982 experiment that confirmed a violation of Bell's inequalities.

Working with Philippe Grangier, Gérard Roger, and Jean Dalibard in France, Aspect tested pairs of entangled photons whose polarization correlations were measured at different detector settings. The observed correlations exceeded the limits that any local hidden-variable theory could satisfy, matching quantum-mechanical predictions instead.

The 1982 work was especially important because the experiment rapidly switched polarizer settings while the photons were in flight. That arrangement addressed the locality concern: one detector could not communicate its setting to the other at light speed before the measurements were completed. Aspect's tests therefore became a landmark in the experimental study of quantum entanglement and the Einstein-Podolsky-Rosen debate.

A common mix-up is crediting John Bell, John Clauser, or Anton Zeilinger. Bell formulated the inequality, Clauser performed earlier pioneering tests, and Zeilinger later advanced and tested entanglement experiments. Aspect led the specific 1982 experiment referenced here and shared the 2022 Nobel Prize in Physics for foundational work on entangled photons.