The Nobel Prize in physics returns to the trio behind quantum computer flea

The Nobel Prize in Physics 2025 has been awarded to John Clarke, Michel Devoret and John Martinis for their work to show how quantum particles can mysteriously cross matter, a process that has contributed to producing the superconductive quantum technology which constitutes the backbone of quantum computers today.

“I am completely stunned,” said Clarke to the Nobel Committee after learning that he had received the award. “It had never come to my mind that this could constitute the basis of a Nobel Prize.”

Quantum particles have a variety of strange behavior, such as their probabilistic nature and the fact that they can only have specific energy levels, rather than a continuum. This sometimes leads them to behave unexpectedly, like digging a tunnel through a apparently solid barrier. Such oddities were discovered by physicists like Erwin Schrödinger in the first decades that followed the start of quantum mechanics.

Even if the implications of these behaviors were clearly deep, underlying for example the theory of nuclear disintegration, scientists could only observe them in unique particles and simple systems. It was not clear if more complex systems, such as electronic circuits, previously only described by classical physics, were also subject to these rules. The quantum tunnel effects, for example, seem to disappear when examining systems on a large scale.

In 1985, Clarke, Martinis and Devoret, all based at the University of California in Berkeley, decided to change this situation. They measured the properties of the loaded particles moving in superconductive circuits called Josephson junctions, a device which earned the British physicist Brian Josephson the Nobel Prize in Physics in 1973. These junctions use wires with zero and separated electrical resistance.

The researchers showed that the particles moving through these junctions acted as a single particle and took distinct energy levels, a distinct quantum effect, and also recorded a tension that would be impossible without having crossed the insulating limit, a clear example of quantum tunnel.

This discovery, and its help to understand how to manipulate quantum systems superconducting similar to it, have revolutionized the field of quantum science, allowing other scientists to test precise quantum physics on silicon chips.

The superconducting quantum circuits also constitute the basis of the basic elements of quantum computers, the quantum bit, or qubit. Today’s most powerful quantum computers, built by companies like Google and IBM, use machines made up of hundreds of superconductive qubits, to which Clarke, Martinis and Devoret’s discoveries have led. “Our discovery, in a way, is the basis of quantum computer science,” said Clarke.

Martinis and Devoret both work for Google Quantum AI, which produced in 2019 the first superconductive quantum computer displaying a quantum advantage compared to a conventional machine. But Clarke told the Nobel Committee that it was not clear, at the time, what would be the influence of their 1985 research. “It had in no way come to mind that this discovery would have such an important impact.”