Alain Aspect
active c. 1947, Agen, France
French physicist who performed the first stringent Bell tests — proving quantum entanglement is real.
Aspect became famous through three experiments in 1981–82 at Orsay: using entangled photon pairs from a calcium cascade and — crucially — polarizer switches changed while photons were in flight, closing the 'locality loophole'. Clear violation of Bell's inequality ruled out local hidden variables. He later studied cold atoms and mentored quantum pioneers.
Nobel-winning work
Aspect's 1982 experiment violated the CHSH inequality by 5 standard deviations with measurement settings chosen after photons left the source — the first test of Bell's theorem near the 'ideal' conditions Einstein feared. The result confirms quantum mechanics cannot be completed by local hidden variables — paving the way for quantum cryptography and computing.
Workplaces: Université Paris-Saclay, Institut d'Optique
France