The 2025 physics Nobel Prize: Launching the era of superconducting quantum electrical circuits

About this event

This event is a ~1h advanced seminar from Prof Daniel Estève in the Stückelberg auditorium. The event is followed by an aperitif.

Abstract

Who and why? In their pioneering work carried out at Berkeley in the mid1980s, the laureates, John Clarke John Martinis and Michel Devoret, first demonstrated that a collective electrical variable, namely the phase difference across a Josephson junction, obeys the rules of quantum mechanics, an issue raised by A.J Leggett. They measured the so-called macroscopic quantum tunneling rate of the junction out of its zero-voltage state, and they demonstrated that the phase has well defined quantum states between which transitions can be induced by applying a resonant microwave signal. These results triggered a huge activity in the field of superconducting quantum circuits for first making quantum bits, and later quantum processors and quantum sensors. I will review some of the main results obtained in this area, and noticeably those of our Quantronics group at CEA Saclay.