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Harvard Physics Colloquium Monday, October 2, 2023 Lecture in Jefferson 250 @ 4:30 PM ***** Michel Devoret, Frederick W. Beinecke Professor of Applied Physics, Yale University ERROR CORRECTION OF A LOGICAL QUANTUM BIT BEYOND THE BREAK-EVEN POINT The accuracy of logical operations on quantum bits (qubits) must be improved for quantum computers to surpass classical ones in useful tasks. To that effect, quantum information
needs to be made robust to noise that affects the underlying physical system. Rather than suppressing noise, quantum error correction aims at preventing it from causing logical errors. This approach derives from the reasonable assumption that noise is local:
it does not act in a coordinated way on different parts of the physical system. Therefore, if a logical qubit is correctly encoded non-locally in the larger Hilbert space of a composite system, it is possible, during a limited time, to detect and correct noise-induced
evolution before it corrupts the encoded information. We will present an experiment based on a superconducting cavity and a transmon synthetic atom – the latter employed here as an auxiliary non-linear element [1] – that implements autonomous
error correction, incorporating novel primitive operations [2] and feedback control based on reinforcement learning [3]. Recently, we have stabilized in real-time a logical qubit manifold spanned by the so-called Gottesman-Kitaev-Preskill grid states, reaching
a correction efficiency such that the lifetime of the encoded information was prolonged by more than a factor of two beyond the lifetime of the physical qubits composing our system [4]. [1] Campagne-Ibarcq, Eickbusch, Touzard,
et al., Nature 584, 368-372 (2020). [2] Eickbusch
et al., Nature Physics 18, 1464 (2022). [3] Sivak
et al., Phys. Rev. X 12, 011059 (2022). [4] Sivak
et al., Nature 616, 50-55 (2023). Michel Devoret graduated with an electrical engineer diploma in 1975 from the Ecole Nationale Supérieure des Télécommunications in Paris and with an MSc in atomic and
molecular physics in 1976 from the University of Paris. He then did his PhD research on the NMR of solid hydrogen at very low temperatures in the laboratory of Prof. Anatole Abragam at CEA Saclay. Working as a post-doc in the group of Prof. John Clarke at
Berkeley, he demonstrated in 1984 with John Martinis that Josephson circuits exhibited quantum energy levels, the basis of today’s superconducting qubits. Back at Saclay, he founded his own research group on mesoscopic superconductivity and single charge effects.
In 2002, he moved to Yale University where his group developed new quantum devices like quantum limited amplifiers and the fluxonium qubit. Recently, his group concentrated on the physics of quantum jumps and the error correction of a logical qubit. Michel
is a member of the National Academy of Sciences and the recipient of several prizes, including the Ampère Prize of the French Academy of Sciences, the John Bell Prize and the Fritz London Memorial Prize. Zoom Details Please click the link below to join the webinar: Passcode: 506586 Or One tap mobile : +19294362866,,97336664192# US (New York) Or Telephone: Passcode: 506586 ***** Events Coordinator O: (617) 495-9801 |