On-chip microwave spectroscopy of an InAs nanowire Cooper-pair transistor

ORAL

Abstract

Controlling both the charging and the Josephson energies of superconducting islands is a crucial requirement for the operation and readout of prospective Majorana-based topological qubits. Here, we present the study of Cooper-pair transistors (CPTs) fabricated from InAs nanowires with superconducting Al shell, a promising platform for the physical realization of topological qubits. By utilizing on-chip microwave spectroscopy, we are able to induce excitations between energy levels of the CPT in a parity conserving manner. We map both the charge- and the photon-like excitations of the system, and show that it is possible to tune the CPT from a Coulomb-blockaded to a transmon-like regime by adjusting the system parameters. The quantum system is exhaustively modeled, allowing us to extract the effective charging and Josephson energies of the CPT. In addition, we study the ground state charge occupation of the CPT and attribute the observed temperature dependence of the even-odd parity structure to the presence of a sub-gap state on the superconducting island.

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Presenters

  • Dominique Laroche

    QuTech, Delft University of Technology

Authors

  • Dominique Laroche

    QuTech, Delft University of Technology

  • Alexander Proutski

    QuTech, Delft University of Technology

  • Bas van 't Hooft

    QuTech, Delft University of Technology

  • Jesper Nygård

    Niels Bohr Institute, Center for Quantum Devices, Center for Quantum Devices and Station-Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Center for Quantum Devices and Station Q Copenhagen, University of Copenhagen, Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute

  • Peter Krogstrup

    Niels Bohr Institute, University of Copenhagen, Center for Quantum Devices and Station Q Copenhagen, University of Copenhagen, Center for Quantum Devices, Center for Quantum Devices, Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Center for Quantum Devices and Microsoft Quantum Lab Copenhagen, Niels Bohr Institute, University of Copenhagen

  • Leo P Kouwenhoven

    Microsoft Station Q at Delft University of Technology, Microsoft Quantum Delft, Qutech, Delft University of Technology, QuTech, Delft University of Technology, Station Q Delft, Microsoft, Microsoft Station Q Delft, Microsoft Station-Q at Delft University of Technology, Microsoft Station Q Delft, Delft University of Technology

  • Attila Geresdi

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