The Royal Swedish Academy of Sciences on October 7 awarded the 2025 Nobel Prizes in Physics to three US scientists, John Clarke, Michel H. Devoret, and John M. Martinis, for their groundbreaking work on quantum mechanical tunneling. The Academy announced that the trio would share the prize for “the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit.”
Their 1980s series of experiments demonstrated how quantum tunneling, the phenomenon where a particle passes through a potential energy barrier even if it doesn’t have enough energy to go over it, can be observed on a macroscopic scale.
During their experiments, the trio built an electronic circuit with two superconductors, components that can conduct a current without any electrical resistance. The system was large enough to be held in a hand and the superconductor components were separated by a thin-layer of non-conductive material. This setup was known as the Josephson junction. In their experiment, they showed that they could observe and manipulate a remarkable effect where every charged particle in the superconductor moves together, acting as one unified particle spread across the whole circuit.
In one famous experiment, the system began in a state where current flows without any voltage. It remained confined in this state, as though blocked by an invisible barrier. In this particular experiment, the system reveals its quantum nature by escaping this zero-voltage state through quantum tunnelling. This phenomenon directly confirmed that quantum mechanics governs not only microscopic particles but also macroscopic systems under the right conditions. The trio further showed that the system follows the rules of quantum mechanics: it is quantized, meaning it can take in or give off only specific, fixed amounts of energy.
The three recipients are all members of the University of California (UC) staff. They join a long line of UC staff and faculty who have won a total of 74 Nobel Prizes, including 23 in physics. Clarke is an emeritus professor of physics at the University of California Berkeley, Michel H. Devoret is a professor of physics at UC Santa Barbara and Yale University, and John M. Martinis is an emeritus professor of physics at UC Santa Barbara.
The Nobel Prize in Physics has been awarded since 1901 and is one of the most prestigious honours in science. When on call with the Nobel committee, Clarke said, “To put it mildly, it was the surprise of my life.” The trio’s work has laid the foundations for the development of quantum technologies, including quantum computing, sensors, and cryptography that will transform the world in the future. The Nobel Prize, totaling 11 million Swedish kronor (approximately $1.2 million), will be shared equally among the three.
