John Clarke, Michel Devoret and John Martinis

Three physicists who in 1984–85 at the University of California, Berkeley asked whether quantum mechanics holds for something macroscopic, a superconducting circuit containing billions of electrons.

They found that the whole circuit could tunnel out of a stable state through a barrier, like a single particle, and that its energies were quantised. The result is the scientific foundation of superconducting qubits. Martinis later led the group at Google that in 2019 reported 'quantum supremacy' with the 53-qubit Sycamore chip, a random-circuit task they estimated would take a supercomputer thousands of years; other researchers argued that classical methods could do it much faster. Devoret and others at Google Quantum AI continued the work, and in 2024 the 105-qubit Willow chip showed logical error rates falling as the error-correcting code (a surface code) grew, the first clear sign of operating below the threshold.

They received the 2025 Nobel Prize in Physics for the discovery of macroscopic quantum tunnelling and energy quantisation in an electric circuit. It is both a milestone of the quantum story and a reminder that Schrödinger's cat was a challenge to ask where the quantum world ends. These experiments suggest that, at least for circuits, it does not.