John Clarke (born 10 February 1942) is a British experimental physicist and Professor Emeritus at the University of California, Berkeley. He is known for his various works on measurement devices based on superconductivity. Steven Girvin has called Clarke "the godfather of superconducting electronics." In the 1980s, Clarke led a research team that included John M. Martinis and Michel Devoret. Their discoveries in macroscopic quantum phenomena using the Josephson effect earned them the Nobel Prize in Physics in 2025.
Education and career John Clarke was born on 10 February 1942 in Cambridge, England. He attended The Perse School, before embarking on a Natural Sciences degree at Christ's College, Cambridge. He graduated with a B.A. in Physics in 1964, and then studied for a Ph.D. in Physics in the Royal Society Mond Laboratory at the University of Cambridge. In 1965, Clarke became one of the first students to enter the newly founded Darwin College, Cambridge, and was the first president of the Darwin College students' association. While conducting his doctoral work under Brian Pippard, Clarke developed a very sensitive voltmeter, which he later called "SLUG" (Superconducting Low-inductance Undulatory Galvanometer). He obtained his doctorate in 1968. Clarke has said at various times that his work was influenced by Nobel laureate Brian Josephson, who predicted the Josephson effect in 1962 and was also a previous student of Pippard. After completing his doctorate, Clarke gained a postdoctoral research position at the University of California, Berkeley, and subsequently worked at Berkeley for his whole academic career, as Assistant Professor (1969), Associate Professor (1971), and as Professor of Physics (1973–2010). In 1969, Clarke also joined Lawrence Berkeley National Laboratory, eventually retiring as a faculty senior scientist in the Materials Sciences Division in 2010. Clarke's association with the University of Cambridge continued, after he moved to the United States. In 1972, he was elected a Fellow of Christ's College; in 1989, he was a visiting fellow at Clare Hall, Cambridge, and in 1998 was elected a by-fellow of Churchill College, Cambridge. Clarke was awarded a D.Sc. from the University of Cambridge in 2003. He was elected an Honorary Fellow of Christ's College in 1997, and of Darwin College in 2023.
Research Clarke's research focuses on superconductivity and superconducting electronics, particularly in the development and application of superconducting quantum interference devices (SQUIDs), which are ultrasensitive detectors of magnetic flux. In 1985, Clarke, John M. Martinis (his Ph.D. student), and Michel Devoret (a postdoctoral researcher at the time) demonstrated the quantum behaviour of a Josephson junction. They showed that at low temperature, a macroscopic electronic state associated with superconductors underwent quantum tunnelling at zero voltage. The same year, by sending microwave pulses of the system, the resonances showed quantised energy levels. This experiment was the first evidence of circuit quantum electrodynamics, that would become later the basis for superconducting quantum computing. The work, which was recognized with the Nobel Prize in Physics in 2025, was largely funded by the Office of Basic Energy Sciences in the United States Department of Energy.
Clarke has also worked in the application of SQUIDs configured as quantum-noise limited amplifiers to search for the axion, a possible component of dark matter.
Recognition Clarke obtained an Alfred P. Sloan fellowship (1970) and a Guggenheim Fellowship (1977).
Memberships
Awards
Works
Selected publications Tesche, Claudia D.; Clarke, John (1 November 1977). "dc SQUID: Noise and optimization". Journal of Low Temperature Physics. 29 (3): 301–331. Bibcode:1977JLTP...29..301T. doi:10.1007/BF00655097. ISSN 1573-7357. Clarke, John; Cleland, Andrew N.; Devoret, Michel H.; Esteve, Daniel; Martinis, John M. (26 February 1988). "Quantum Mechanics of a Macroscopic Variable: The Phase Difference of a Josephson Junction". Science. 239 (4843): 992–997. Bibcode:1988Sci...239..992C. doi:10.1126/science.239.4843.992. PMID 17815701. Clarke, J. (August 1989). "Principles and applications of SQUIDs". Proceedings of the IEEE. 77 (8): 1208–1223. Bibcode:1989IEEEP..77.1208C. doi:10.1109/5.34120. ISSN 1558-2256. McDermott, Robert; Trabesinger, Andreas H.; Muck, Michael; Hahn, Erwin L.; Pines, Alexander; Clarke, John (22 March 2002). "Liquid-state NMR and scalar couplings in microtesla magnetic fields". Science. 295 (5563): 2247–2249. Bibcode:2002Sci...295.2247M. doi:10.1126/science.1069280. ISSN 1095-9203. PMID 11910105. Clarke, John; Hatridge, Michael; Mössle, Michael (2007). "SQUID-detected magnetic resonance imaging in microtesla fields". Annual Review of Biomedical Engineering. 9: 389–413. doi:10.1146/annurev.bioeng.9.060906.152010. ISSN 1523-9829. PMID 17328671.
Books Srinath, S. (1 August 2006). Clarke, John (ed.). "A Review of: "The SQUID Handbook: Fundamentals and Technology of SQUIDS and SQUID Systems": John Clarke and Alex I. Braginski (editors), Vol. 1". Materials and Manufacturing Processes. 21 (5): 583. doi:10.1080/10426910500503706. ISSN 1042-6914.
Notes
References
External links John Clarke on Nobelprize.org
Further reading Clarke, John; Silver, Arnold; Braginski, A.I. (2012). "5. SQUIDS and Detectors". In Rogalla, Horst; Kes, Peter H. (eds.). 100 Years of Superconductivity. Boco Raton: Taylor & Francis. pp. 311–327. ISBN 978-1-4398-4948-4.
