High-fidelity controlled-Z gate with maximal intermediate leakage operating at the speed limit in a superconducting quantum processor

ORAL

Abstract

Simple tuneup of high-fidelity two-qubit gates is essential for the scaling of quantum processors. Here, we introduce the sudden variant (SNZ) of the Net Zero scheme realizing high-fidelity, repeatable controlled-Z (CZ) gates by baseband flux control of transmon frequency. SNZ achieves CZ gates at the speed limit of transverse coupling between computational and non-computational states by maximizing intermediate leakage. Beyond speed, the key advantage of SNZ over fast-adiabatic approaches is tuneup simplicity, owing to the regular structure of conditional phase and leakage as a function of two control parameters. We realize SNZ CZ gates in a multi-transmon processor, reaching 99.87±0.27% fidelity with 0.15 ± 0.02% leakage. We use numerical simulations with experimental input parameters to dissect the error budget and compare SNZ to conventional NZ , finding SNZ to outperform. SNZ is compatible with scalable schemes for quantum error correction and adaptable to arbitrary conditional-phase gates useful in NISQ applications.

*Research funded by IARPA (U.S. Army Research Office Grant No. W911NF-16-1-0071) and by Intel Corporation.

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Presenters

  • Hany Ali

    • Delft University of Technology

Authors

  • Hany Ali

    • Delft University of Technology

  • Victor Negirneac

    • Delft University of Technology
    • Qblox

  • Nandini Muthusubramanian

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

  • Francesco Battistel

    • Delft University of Technology
    • QuTech, Delft University of Technology

  • Ramiro Sagastizabal

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

  • Miguel S Moreira

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

  • Jorge Marques

    • Delft University of Technology

  • Wouter Vlothuizen

    • Delft University of Technology
    • TNO

  • Marc Beekman

    • Delft University of Technology

  • Nadia Haider

    • Delft University of Technology
    • Netherlands Organization for Scientific Research (TNO)
    • Netherlands Organisation for Applied Scientific Research (TNO)

  • Alessandro Bruno

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

  • Leonardo DiCarlo

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