October 8, 2025
‘Much-loved’ UW collaborator John Clarke wins the Nobel Prize in Physics
Gray Rybka (left), a UW professor of physics and Leslie Rosenberg (right), a UW professor emeritus of physics prepare to lower the Axion Dark Matter Experiment into the bore of a large superconducting magnet. This work was made possible by Nobel Laureate John Clarke’s contributions.Mary Levin/University of Washington
The Royal Swedish Academy of Sciences on Tuesday awarded the 2025 Nobel Prize in Physics jointly to John Clarke, Michel H. Devoret and John M. Martinis, “for the discovery of macroscopic quantum mechanical tunneling and energy quantization in an electric circuit.”
Clarke, a professor emeritus of physics at the University of California, Berkeley, collaborates with the Axion Dark Matter Experiment at the University of Washington. ADMX scans for evidence of dark matter from beneath the Seattle campus, in a cold dark box surrounded by a powerful magnetic field. The experiment is managed by the U.S. Department of Energy’s Fermi National Accelerator Laboratory and it hinges on technology designed by Clarke.
John Clarke, a professor emeritus of physics at the University of California, Berkeley, who on Tuesday won the 2025 Nobel Prize in Physics, along with two others.Darwin College
“I was elated upon hearing the news about John. Simply elated,” said Leslie Rosenberg, a UW professor emeritus of physics and lead scientist at ADMX.
The three laureates were recognized for experiments conducted in 1984 and 1985 that captured two quantum mechanical properties at the visible scale. Clarke’s brainchild, which caught Rosenberg’s attention 25 years ago, is a Superconducting Quantum Interference Device, or SQUID, which can make ultrasensitive measurements.
“John Clarke first got involved with ADMX around 2000,” Rosenberg recalled. “To this day, he remains a much-loved ADMX collaborator.”
The relationship began when ADMX organized a workshop at Lawrence Berkeley Laboratory to brainstorm solutions to a technical issue the researchers had encountered. The way the experiment searches for dark matter is akin to a radio searching for a station, but instead of music, it is looking for axions — the particles theorized to make up dark matter.
Detecting axions requires amplifying very, very quiet microwaves. At the time, the group only had access to noisy electronic amplifiers, which were drowning out the very signal they sought to capture. At the workshop, Clarke presented a SQUID amplifier as a potential solution.
“We considered all kinds of alternative technologies, but none fit the bill,” Rosenberg said. “The SQUID amplifiers were indeed the breakthrough we needed.”
The top of the ADMX experiment inside the magnet bore, featuring the maze of vacuum plumbing & systems, cryogenic plumbing & systems, gas plumbing & systems, sensor wiring, RF & microwave wiring, and magnet leads.Mark Stone/University of Washington
Clarke joined ADMX and brought the amplifiers with him. Gray Rybka, a UW professor of physics and co-spokesperson for ADMX, was a postdoc at the time.
“The SQUID amplifiers gave us the sensitivity necessary to do a search,” Rybka said. “We’ve been operating for years and years and have only explored a fraction of the space, but we couldn’t have even started without these amplifiers.”
ADMX is still using an iteration of Clarke’s original amplifier, improved upon by his students over the years. Still, the “big transition,” was moving to the SQUID amplifier, and that is just one example of how this technology can revolutionize an experiment.
“The laureates moved the field of particle physics from classical measurement to quantum sensing,” Rybka said. “It makes stuff that used to just be on the blackboard — quantum mechanics — experimentally accessible and even useful. In my opinion, you wouldn’t have modern quantum computers without the work done by this group.”
Tag(s): College of Arts & Sciences • Department of Physics • Gray Rybka • Leslie Rosenberg • Research Makes America