John Clarke (physicist)

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—which was supervised by 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 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. == Awards and honours ==

Clarke obtained an Alfred P. Sloan fellowship (1970) and a Guggenheim Fellowship (1977). Clarke was elected a Fellow of the Royal Society in 1986. Comstock Prize in Physics in 1999, the Hughes Medal He was elected a Foreign Associate of the National Academy of Sciences in May 2012. He was elected to the American Philosophical Society in 2017. In 2021, the Micius Quantum Prize was jointly awarded to Clarke, Michel Devoret and Yasunobu Nakamura. Clarke, Michel Devoret, and John M. Martinis were jointly awarded the 2025 Nobel Prize in Physics "for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit". == Works ==

Selected publications • • • • • Books • == References ==