John Clarke, an emeritus professor of physics at the University of California, Berkeley, has been awarded the 2025 Nobel Prize in Physics. Clarke received the honor for his work on quantum tunneling, a phenomenon where particles move through barriers that would be impossible according to classical physics.
Clarke shares the prize with Michel H. Devoret and John M. Martinis, who were affiliated with UC Santa Barbara during their prize-winning research. The Nobel committee recognized the trio “for the discovery of macroscopic quantum mechanical tunneling and energy quantization in an electric circuit.”
Their experiments in the early 1980s involved demonstrating quantum tunneling using a simple electrical circuit containing a superconductor. This type of material allows electrical current to flow without resistance.
In a phone call with the Nobel committee during a press conference in Stockholm, Clarke expressed his surprise at receiving the award. “To put it mildly, it was the surprise of my life,” he said. That his work was Nobel Prize worthy “had not occurred to us in any way.”
Clarke acknowledged his colleagues’ significant contributions: “I was in principle the leader of the group, of course, but their contributions are just overwhelming.”
Following this research, Clarke developed an ultrasensitive detector known as a SQUID (superconducting quantum interference device). He has applied SQUIDs across various fields such as detecting NMR signals at ultralow frequencies, geophysics, nondestructive evaluation of materials, and biosensing.
Currently, Clarke is collaborating with the Axion Dark Matter Experiment (ADMX), for which he designed a low-noise superconducting quantum amplifier based on SQUIDs. ADMX is focused on searching for axions as potential dark matter candidates. The amplifiers he created have also been used to read out superconducting qubits for quantum computers.
Clarke’s accolades include being named a Fellow of the Royal Society of London and an Honorary Fellow at Christ’s College, Cambridge. He has received several awards such as the University of California’s Distinguished Teaching Award and technology honors including the Fritz London Memorial Award for low temperature physics and the National Academy of Sciences Comstock Prize in physics.
