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Gray Rybka (left), a professor of physics at UW, and Leslie Rosenberg (right), a professor emeritus of physics at UW, prepare to position the Axion Dark Matter Experiment into the bore of a massive superconducting magnet. This endeavor was made feasible through the contributions of Nobel Laureate John Clarke.Mary Levin/University of Washington
The Royal Swedish Academy of Sciences awarded the 2025 Nobel Prize in Physics to John Clarke, Michel H. Devoret, and John M. Martinis on Tuesday, recognizing their work “for the discovery of macroscopic quantum mechanical tunneling and energy quantization in an electric circuit.”
Clarke, an emeritus professor of physics at the University of California, Berkeley, collaborates with the Axion Dark Matter Experiment at the UW. The ADMX seeks evidence of dark matter from beneath the Seattle campus, situated in a cold, dark box encased by a powerful magnetic field. This project is overseen by the U.S. Department of Energy’s Fermi National Accelerator Laboratory, utilizing technology crafted by Clarke.
John Clarke, an emeritus professor of physics at the University of California, Berkeley, who received the 2025 Nobel Prize in Physics on Tuesday, alongside two colleagues.Darwin College
“I was thrilled when I heard the news about John. Absolutely thrilled,” expressed Leslie Rosenberg, a professor emeritus of physics at UW and the lead scientist at ADMX.
The trio of laureates was honored for experiments performed in 1984 and 1985 that captured two properties of quantum mechanics at a visible scale. Clarke’s innovative approach, which interested Rosenberg 25 years ago, involves a Superconducting Quantum Interference Device, or SQUID, capable of ultra-sensitive measurements.
“John Clarke first engaged with ADMX around 2000,” recalled Rosenberg. “Even now, he remains a much-admired collaborator at ADMX.”
The partnership commenced when ADMX hosted a workshop at Lawrence Berkeley Laboratory to conceptualize solutions to a technical challenge faced by the researchers. The methodology by which the experiment investigates dark matter resembles a radio tuning in to a station, but instead of music, it seeks axions — the particles theorized to comprise dark matter.
Detecting axions necessitates amplifying exceedingly faint microwaves. During that time, the team had only access to noisy electronic amplifiers, which drowned out the very signals they aimed to capture. At the workshop, Clarke introduced a SQUID amplifier as a possible resolution.
“We examined various alternative technologies, yet none met our needs,” said Rosenberg. “The SQUID amplifiers were indeed the breakthrough we required.”
The upper section of the ADMX experiment situated inside the magnet bore, illustrating the intricate maze of vacuum systems, cryogenic systems, gas systems, sensor wiring, RF & microwave wiring, and magnet leads.Mark Stone/University of Washington
Clarke joined ADMX and brought the amplifiers along with him. Gray Rybka, a physics professor at UW and co-spokesperson for ADMX, was a postdoctoral researcher at that time.
“The SQUID amplifiers provided us the sensitivity essential to conduct a search,” Rybka noted. “We’ve been functioning for many years and have only examined a fraction of the area, but we couldn’t have even initiated without these amplifiers.”
ADMX continues to utilize an iteration of Clarke’s original amplifier, which has been refined by his students over time. Nevertheless, the “significant transition” was the adoption of the SQUID amplifier, exemplifying how this technology can transform an experiment.
“The laureates transitioned the field of particle physics from classic measurement to quantum sensing,” Rybka stated. “It makes concepts that were previously confined to theoretical discussion — quantum mechanics — experimentally feasible and even practical. In my view, modern quantum computers would not exist without the contributions made by this group.”
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