The Aspect experiment tested Bell inequalities using entangled photons and found quantum correlations.
Alain Aspect and collaborators carried out a series of experiments in 1981 and 1982. Their setup used pairs of polarization-entangled photons and rapidly switched measurement settings while the photons were in flight. The measured correlations violated Bell inequalities, agreeing with quantum mechanics rather than local hidden-variable predictions.
The experiments improved on earlier tests by addressing important experimental limitations, especially the timing of analyzer settings. They did not prove that information travels faster than light, because the individual outcomes remain unpredictable and no controllable message is transmitted. Later Bell tests closed additional loopholes, but Aspect’s work was a landmark in experimental quantum foundations.