Topic: Macroscopic quantum tunnelling

Michel Devoret retraces the experimental discovery of macroscopic quantum tunnelling and quantised energy levels in superconducting electrical circuits. The lecture explains how Josephson circuits became controllable quantum systems and how these experiments opened a route from observing quantum behaviour in a macroscopic device to engineering artificial atoms. He connects this foundational work, recognised by the 2025 Nobel Prize in Physics shared with John Clarke and John Martinis, to the development of superconducting qubits and present approaches to quantum computing. The account links th

John Clarke, Michel H. Devoret and John M. Martinis trace the discovery that a macroscopic electrical circuit can display quantum tunnelling and discrete energy levels. Clarke connects early superconducting measuring devices with experiments on current-biased Josephson junctions. Microwave-induced resonances and the crossover from thermal activation to temperature-independent escape provide tests of quantum behaviour. Devoret explains how superconducting circuits became controllable artificial atoms, with Josephson elements enabling engineered energy spectra, qubits and quantum-limited amplif