Microwave Sensing of Andreev Bound States in a Gate-Defined Superconducting Quantum Point Contact

ORAL

Abstract

Andreev bound states (ABSs) are coherent superpositions of electrons and holes bound at a junction between two superconductors. Hybrid superconductor-semiconductor junctions allow exquisite control over the number and energy of ABSs using capacitively-coupled gate electrodes. Here we use circuit quantum electrodynamics (cQED) to monitor ABSs in a quantum point contact defined by surface gates over a proximitized two-dimensional electron gas. We infer the ABS structure by comparing a microphysical model of the junction to fits of the cavity frequency as a function of phase difference and gate voltage. Close to pinch-off, we identify features consistent with the presence of a single ABS and describe the Andreev-cavity interaction using a dispersive Jaynes-Cummings model. By fitting the weak Andreev-cavity coupling, we extract ~GHz decoherence consistent with charge noise and the transmission dispersion associated with a single localized state.

*MSCA No. 750777, EP/L020963/1, Microsoft Project Q.

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Publication: Chidambaram et al., arXiv:2102.05206v1 (2021)

Presenters

  • Malcolm R Connolly

    • Imperial College London

Authors

  • Malcolm R Connolly

    • Imperial College London

  • Vivek Chidambaram

    • University of Oxford

  • Anders Kringh?j

    • Niels Bohr Inst

  • Lucas Casparis

    • NBI, Microsoft Quantum Lab

  • Ferdinand Kuemmeth

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Denmark & QDevil ApS, Denmark
    • Niels Bohr Inst

  • Tiantian Wang

    • Purdue University

  • Candice Thomas

    • Purdue University
    • Purdue University, Microsoft Quantum Materials Lab-Purdue, West Lafayette, Indiana 47907, USA
    • CEA

  • Sergei Gronin

    • Purdue University, Microsoft Quantum Materials Lab-Purdue, West Lafayette, Indiana 47907, USA
    • Microsoft Quantum Materials Lab-Purdue
    • Purdue University

  • Geoffrey C Gardner

    • Purdue University

  • Michael J Manfra

    • Department of Physics and Astronomy, Birck Nanotechnology Center, and Microsoft Quantum Lab Purdue, Purdue University
    • Purdue University
    • Purdue University, West Lafayette, Indiana 47907, USA

  • Karl D Petersson

    • Niels Bohr Inst