John Clarke

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.

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. 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.

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 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 Year Organisation Type 1986 Royal Society Fellow 2017 American Philosophical Society Member

Awards Year Organisation Award Citation 1998 American Physical Society Joseph F. Keithley Award "For his experimental and theoretical studies of Superconducting Quantum Interference Devices (SQUIDs), advancing the state-of-the-art of measurement science by applying SQUIDs to many areas of both fundamental and applied physics such as high-Tc superconductor analyses, NMR amplifiers, and cryogenic comparators." 1999 National Academy of Sciences Comstock Prize in Physics "For his major contributions to the development of superconducting quantum interference devices (SQUIDS) and their use for scientific measurements, especially involving electricity, magnetism, and electromagnetic waves." 2004 Royal Society Hughes Medal "For his outstanding research, leading the world in the invention, building and development of innovative new Superconducting QUantum Interference Devices (SQUID), in their theory and in their application to a plethora of fundamental problems and their investigative tools." 2025 Royal Swedish Academy of Sciences Nobel Prize in Physics "For the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit."

Works Selected publications

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