New Delhi, Oct 7 (UNI) Nobel Prize for Physics 2025 has been awarded to three US physicists for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit, the Nobel Committee announced today.

The three are John Clarke of the University of California, Berkeley, Michel H. Devoret of Yale University, New Haven, and University of California, and John M. Martinis of the University of California, the Royal Swedish Academy of Sciences said in a statement.

''Their experiments on a chip revealed quantum physics in action,'' the statement said.

A major question in physics is the maximum size of a system that can demonstrate quantum mechanical effects. This year's Nobel Prize 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.

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. 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.

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.