John Francis Clauser, PhD

John Clauser  received his B.S. in physics from the California Institute of Technology in 1964, his M.A. in physics in 1966 and Ph.D. in physics in 1969 from Columbia University. From 1969 to 1996 he worked at Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and the University of California, Berkeley. John was awarded the Wolf Prize in Physics in 2010, together with Alain Aspect and Anton Zeilinger for their observations of non-local quantum entanglement and experimental tests of Local Realism. In 1969, with Michael Horne, Abner Shimony, and Richard Holt, inspired by theoretical results by John Bell, he proposed the first test of local hidden variable theories, and provided the first experimentally testable CHSH-Bell's Theorem prediction for these theories -- the Clauser-Horne-Shimony-Holt (CHSH) inequality. In 1972, working with Stuart Freedman, he carried out the first experimental test of the CHSH inequality's prediction. This was the world's first observation of non-local quantum entanglement, and was the first experimental observation of a violation of a Bell inequality. In 1976 he carried out the world's second experimental test of the CHSH inequality prediction. In 1974, working with Michael Horne, he formulated the theory of Local Realism as a generalization of local hidden-variable theories, and first showed that a generalization of Bell's Theorem provides severe constraints for all Local Realistic theories of nature. That work introduced the Clauser–Horne (CH) inequality as the first fully general experimental requirement set by Local Realism. It has only recently (2013) been tested experimentally. He also introduced the "CH no-enhancement assumption", whereupon the CH inequality reduces to the CHSH inequality, and whereupon associated experimental tests also constrain Local Realism. In 1974 he made the first observation of sub-Poissonian statistics for light (via a violation of the Cauchy–Schwarz inequality for classical electromagnetic fields), and thereby first experimentally proved that photons can behave like localized particles and not like brief pulses of electromagnetic radiation. In 1987-1991 he proposed (and patented) atom interferometers as useful ultra-sensitive inertial and gravity sensors. In 1992, with Matthias Reinsch, he first deduced the number-theoretic properties of the fractional Talbot effect, and invented the Talbot-Lau interferometer. In 1990-1997, with Shifang Li, he first used Talbot-Lau interferometry to build an atom interferometer. In 1998 he invented and patented use of the Talbot-Lau interferometry for "Ultrahigh Resolution Interferometric X-ray Imaging". This invention, in turn, allows x-ray phase-contrast medical imaging of soft tissue.

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See, Public Broadcasting System - Nova, 2018, Einstein’s Quantum Riddle – excerpt: “Collecting Evidence for Quantum Entanglement | Einstein’s Quantum Riddle” (Use this resource to discover how physicist John Clauser developed an experiment to test John Stewart Bell's theory and how other scientists responded to its limitations in subsequent experiments.)”.

https://ca.pbslearningmedia.org/resource/nveqr-sci-evidence/collecting-evidence-for-quantum-entanglement-einsteins-quantum-riddle/