John Clauser is a distinguished American theoretical and experimental physicist renowned for his pivotal contributions to the foundations of quantum mechanics. His groundbreaking work on the Clauser–Horne–Shimony–Holt inequality has significantly advanced the understanding of quantum entanglement. In recognition of his exceptional research, Clauser was awarded the 2022 Nobel Prize in Physics, alongside Alain Aspect and Anton Zeilinger, for their experiments with entangled photons that established the violation of Bell inequalities and pioneered quantum information science.

Clauser’s academic journey began with a Bachelor of Science in physics from the California Institute of Technology in 1964, followed by a Master of Arts and a Doctor of Philosophy from Columbia University. His early career included a postdoctoral position at the University of California, Berkeley, where he conducted the first experimental test of the CHSH-Bell’s theorem predictions in 1972. This landmark experiment marked the first observation of a violation of a Bell inequality, laying the groundwork for future explorations in quantum mechanics.

Throughout his career, Clauser has continued to push the boundaries of quantum physics. In 1974, he introduced the Clauser–Horne inequality, which provided critical constraints for local realistic theories. His work also included the first observation of sub-Poissonian statistics for light, demonstrating the particle-like nature of photons. Clauser’s commitment to advancing the field is further exemplified by his publication of the newsletter Epistemological Letters, aimed at discussing the philosophy of quantum mechanics.

In addition to the Nobel Prize, Clauser received the Wolf Prize in Physics in 2010, further solidifying his status as a leading figure in the scientific community. His contributions have not only enriched theoretical physics but have also paved the way for practical applications in quantum computing and secure communication technologies, marking him as a pivotal figure in the evolution of modern physics.