A Nobel for the quantum circuit

On 7 October, the Nobel Committee announced the 2025 Nobel Prize in Physics, and the award went to three physicists whose work is measured in a particular unit: the quantum circuit. John Clarke, Michel Devoret and John Martinis received the prize for the discovery of macroscopic quantum tunnelling and energy quantisation in an electric circuit, the body of experimental work that established that the strange rules of the quantum world, long confined to atoms and particles, operate in circuits large enough to be built, held and measured. The award recognises the physics on which the entire field of superconducting quantum computing is built.

The discovery at the centre of the prize is a matter of demonstrating the quantum in the engineered. Tunnelling, the passage of a particle through a barrier that classical physics says it cannot cross, and quantisation, the appearance of energy only in discrete steps, had been understood since the early years of quantum theory; the achievement of the laureates was to show both operating in a superconducting circuit, a device that behaves as a single quantum object despite being a manufactured piece of electrical engineering. The experiments were, in the committee’s description, among the first to make the quantum world’s peculiarities concrete in a system that a person could hold.

The consequences of the discovery were felt decades later, in the architecture of quantum computing. A superconducting circuit that obeys quantum rules is a qubit, the basic unit of a quantum computer, and the machines now being built by companies and laboratories around the world are the direct descendants of the circuits the laureates studied. The prize, awarded for work whose significance was not fully visible at the time, is a recognition of the long arc between a fundamental experiment and an engineering platform, and of the decades of patience that the arc requires.

The three laureates also represent the field’s particular sociology: the combination of the theorist’s clarity and the experimentalist’s stubbornness, spread across institutions and generations, that turns an idea into an instrument. Clarke’s early demonstrations, Devoret’s precise measurements, Martinis’ scaling of the circuits into working processors, each step built on the last, and the prize binds the sequence together into a single story of how a laboratory curiosity became the basis of an industry. The citations, spanning decades, are also a reminder of how long the route from a fundamental discovery to a recognised prize can be, and of how many of the field’s pioneers did the work long before the field had a name.

The Nobel week moves on, to chemistry, to literature, to peace, but the physics prize has set the tone: an award for the quantum circuit, for the discovery that the world’s smallest physics could be engineered into the world’s most useful devices. The quantum computers of the coming decades will carry the quiet signature of the work announced in October, and the circuit, the object the laureates made quantum, will be remembered as one of the places where the century’s physics met the century’s engineering.