John Francis Clauser (cropped)

John Francis Clauser (/ˈklaʊzər/; born December 1, 1942) is an American theoretical and experimental physicist known for contributions to the foundations of quantum mechanics, in particular the Clauser–Horne–Shimony–Holt inequality.[1]

Clauser was awarded the 2022 Nobel Prize in Physics, jointly with Alain Aspect and Anton Zeilinger "for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science".[2]


Clauser was born in Pasadena, California. His father, Francis H. Clauser, was a professor of aeronautical engineering who founded and chaired the aeronautics department at Johns Hopkins University. He later served as the Clark Blanchard Millikan Professor of Engineering at the California Institute of Technology (Caltech).[3][4] His mother, Catharine McMillan, was the humanities librarian at Caltech and sister of 1951 Nobel Prize in Chemistry laureate Edwin McMillan.[5]

He received a bachelor of science in physics from Caltech in 1964, where he was a member of Dabney House.[6] He received a master of arts in physics in 1966 and a doctor of philosophy in physics in 1969 from Columbia University[1] under the direction of Patrick Thaddeus.[7][8]

From 1969 to 1997, he worked mainly at the University of California, Berkeley, Lawrence Berkeley National Laboratory, and Lawrence Livermore National Laboratory.[1] In 1972, working with Stuart Freedman, he carried out the first experimental test of the CHSH-Bell's theorem predictions. This was the first experimental observation of a violation of a Bell inequality.[9]

In 1974, working with Michael Horne, he first showed that a generalization of Bell's Theorem provides severe constraints for all local realistic theories of nature (a.k.a. objective local theories). That work introduced the Clauser–Horne (CH) inequality as the first fully general experimental requirement set by local realism. It 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. Also 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, for the first time, demonstrated an unambiguous particle-like character for photons. In 1976 he carried out the world's second experimental test of the CHSH-Bell's Theorem predictions.[10]

Clauser was awarded the Wolf Prize in Physics in 2010 together with Alain Aspect and Anton Zeilinger. The three were also jointly awarded the Nobel Prize in Physics in 2022.[11]
See also

Epistemological Letters


"John F. Clauser". American Institute of Physics.
"The Nobel Prize in Physics 2022". The Royal Swedish Academy of Sciences (Press release). October 4, 2022.
"Proving that Quantum Entanglement is Real". California Institute of Technology. September 20, 2022. Retrieved October 6, 2022.
"Dr. Francis H. Clauser". NAE Website. Retrieved October 6, 2022.
"Caltech Alum Wins Nobel Prize in Physics". California Institute of Technology. October 4, 2022. Retrieved October 6, 2022.
The Big T. Associated Students of the California Institute of Technology. 1963.
Clauser, John F. (1970). Measurement of the Cosmic Microwave Background by Optical Observations of Interstellar Molecules (Ph.D. thesis). Columbia University. OCLC 145659. ProQuest 302516464.
"Patrick Thaddeus (1932–2017)" (PDF). Biographical Memoirs. National Academy of Sciences. p. 12.
Freedman, Stuart J.; Clauser, John F. (April 3, 1972). "Experimental Test of Local Hidden-Variable Theories". Physical Review Letters. 28 (14): 938-941. Bibcode:1972PhRvL..28..938F. doi:10.1103/PhysRevLett.28.938. Retrieved October 5, 2022.
"Proving that Quantum Entanglement is Real". California Institute of Technology. September 20, 2022. Retrieved October 6, 2022.
"The Nobel Prize in Physics 2022". Retrieved October 4, 2022.

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