The Nobel Prize in Physics 2025 was on Tuesday awarded to the American trio of John Clarke, Michel H. Devoret, and John M. Martinis for their experiments on a chip which revealed quantum physics in action.
The Royal Swedish Academy of Sciences, which awards the prize, according to a statement, said the recognition was “for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit”
The Physics laureates conducted experiments with an electrical circuit in which they demonstrated both quantum mechanical tunnelling and quantised energy levels in a system big enough to be held in the hand.
This helps answer a major question in physics, which asks the maximum size of a system that can demonstrate quantum mechanical effects.
Quantum mechanics allows a particle to move straight through a barrier, using a process called tunnelling. As soon as large numbers of particles are involved, quantum mechanical effects usually become insignificant.
According to the committee, the laureates’ experiments demonstrated that quantum mechanical properties can be made concrete on a macroscopic scale.
In 1984 and 1985, John Clarke, Michel H. Devoret and John M. Martinis conducted a series of experiments with an electronic circuit built of superconductors, components that can conduct a current with no electrical resistance.
In the circuit, the superconducting components were separated by a thin layer of non-conductive material, a setup known as a Josephson junction. By refining and measuring all the various properties of their circuit, they were able to control and explore the phenomena that arose when they passed a current through it.
Together, the charged particles moving through the superconductor comprised a system that behaved as if they were a single particle that filled the entire circuit.
This macroscopic particle-like system is initially in a state in which current flows without any voltage. The system is trapped in this state, as if behind a barrier that it cannot cross.
In the experiment, the system shows its quantum character by managing to escape the zero-voltage state through tunnelling. The system’s changed state is detected through the appearance of a voltage.
The committee added that the laureates could also demonstrate that the system behaves in the manner predicted by quantum mechanics – it is quantised, meaning that it only absorbs or emits specific amounts of energy.
“It is wonderful to be able to celebrate the way that century-old quantum mechanics continually offers new surprises. It is also enormously useful, as quantum mechanics is the foundation of all digital technology,” says Olle Eriksson, Chair of the Nobel Committee for Physics.
The Nobel committee added that this year’s candidates provided opportunities for developing the next generation of quantum technology, including quantum cryptography, quantum computers, and quantum sensors.
On Monday, the Nobel committee had awarded the prize in medicine to three scientists, two Americans and one Japanese.
On Wednesday, the prize will awarded in Chemistry followed by literature on Thursday, peace of Friday, and economics next week Monday.