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Controlling the charge dispersion of a nearly-open superconducting island

ORAL

Abstract

Isolation from the environment determines the extent to which charge is confined on an island, which manifests experimentally through Coulomb oscillations such as charge dispersion. In superconducting circuits, the link to the environment has typically been formed from tunnel junctions. If instead a transparent ballistic junction forms the link between the superconducting island and the environment, Coulomb oscillations are predicted to suppress far more rapidly than for tunnel junctions due to imaginary-time Landau-Zener tunneling. Here we investigate the charge dispersion of a nanowire transmon hosting a quantum dot in the junction. We observe rapid suppression of the charge dispersion consistent with the scaling law resulting from diabatic transitions between Andreev bound states. We also observe greatly improved qubit coherence times at the point of highest charge dispersion suppression. Our observations further our fundamental understanding of charging effects in superconductors and suggests novel approaches for building charge-insensitive qubits.

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Presenters

  • Arno Bargerbos

    QuTech, Delft University of Technology, Delft University of Technology

Authors

  • Arno Bargerbos

    QuTech, Delft University of Technology, Delft University of Technology

  • Willemijn Uilhoorn

    QuTech and Kavli Institute of Nanoscience, Delft University of Technology, QuTech, Delft University of Technology

  • Bernard Van Heck

    Microsoft Quantum Lab Delft, Delft University of Technology, 2600 GA Delft, The Netherlands, Microsoft, Quantum Lab Delft, Microsoft, Microsoft Quantum Lab Delft

  • Chung-Kai Yang

    Quantum Lab Delft, Microsoft, Microsoft Corp

  • Peter Krogstrup

    Microsoft Quantum Materials Lab and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Kanalvej 7, 2800 Kongens Lyngby, Denmark, Microsoft, Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen and Microsoft Quantum Materials Lab Copenhagen, Quantum Materials Lab Copenhagen, Microsoft, Center for Quantum Devices and Microsoft Quantum Lab–Copenhagen, Center for Quantum Devices and Microsoft Quantum Lab Copenhagen, Niels Bohr Institute, University of Copenhagen, Microsoft Corp

  • Leo P Kouwenhoven

    Dept. of Physics, Technical University, Delft, The Netherlands, Microsoft Quantum Lab Delft, Microsoft Quantum Lab Delft, Delft University of Technology, Microsoft Corp Delft, Quantum Lab Delft, Microsoft, Delft University of Technology, QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Microsoft Corp

  • Gijs De Lange

    Microsoft Quantum Lab Delft, 2628 CJ, Delft, The Netherlands, Quantum Lab Delft, Microsoft, Applied Physics, Yale University, QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Microsoft Corp

  • Angela Kou

    Quantum Lab Delft, Microsoft, Microsoft Corp