Variability metrics in Josephson Junction fabrication for Quantum Computing circuits

ORAL

Abstract

Multi-qubit gates depend on the relative frequencies of the qubits. To reliably build multi-qubit devices therefore requires careful fabrication of Josephson junctions in order to precisely set their critical currents. The Ambegaokar-Baratoff relation between tunnel conductance and critical current implies a correlation between qubit frequency spread and tunnel junction resistance spread. Here we discuss measurement of large numbers of tunnel junctions to assess these resistance spreads, which can exceed 5{\%} of mean resistance. With the goal of minimizing these spreads, we investigate process parameters such as lithographic junction area, evaporation and masking scheme, oxidation conditions, and substrate choice, as well as test environment, design and setup. In addition, trends of junction resistance with temperature are compared with theoretical models for further insights into process and test variability.

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Authors

  • Sami Rosenblatt

    • IBM T. J. Watson Research Center

  • Jared Hertzberg

    • IBM T. J. Watson Research Center

  • Markus Brink

    • IBM T. J. Watson Research Center

  • Jerry Chow

    • IBM T. J. Watson Research Center

  • Jay Gambetta

    • IBM T. J. Watson Research Center

  • Zhaoqi Leng

    • Princeton University

  • Andrew Houck

    • Princeton University

  • J.J. Nelson

    • Syracuse University

  • Britton Plourde

    • Syracuse University

  • Xian Wu

    • National Institute of Standards and Technology, Boulder, CO

  • Russell Lake

    • National Institute of Standards and Technology, Boulder, CO

  • Jeff Shainline

    • National Institute of Standards and Technology, Boulder, CO

  • David Pappas

    • National Institute of Standards and Technology, Boulder, CO

  • Umeshkumar Patel

    • University of Wisconsin, Madison

  • Robert McDermott

    • University of Wisconsin, Madison