Illustration of the US physicist John Clauser (born 1942). Clauser is best known for his contributions to the foundations of quantum mechanics, in particular the Clauser-Horne-Shimony-Holt (CHSH) inequality relating to quantum entanglement. In 1972, with Stuart Freedman, he carried out the first experimental test of the CHSH-Bell's theorem predictions. This was the world's first observation of quantum entanglement, and was the first experimental observation of a violation of a Bell inequality. Clauser was awarded a share of the 2022 Nobel Prize in Physics for this work along with Alain Aspect and Anton Zeilinger.