Epitaxial Josephson junctions for superconducting qubits made by wafer-bonding

ORAL

Abstract

State-of-the-art transmons most often utilize Al/AlO x /Al Josephson junctions (JJs) even though the
amorphous AlO x is known to be defective and lossy. A scalable process to realize epitaxial JJs with low
loss barrier dielectrics could improve qubit performance beyond state-of-the-art; however, challenges in
materials integration have not yet been overcome. In this work, a wafer-bonding technique is used to
realize epitaxial JJ structures utilizing conventional semiconductors for the JJ dielectric. Semiconductors
and epitaxial superconductors are grown by molecular beam epitaxy on III-V semiconductor substrates
and bonded to low-loss substrates. Selective etching is used to remove the III-V substrate followed by
surface cleaning and superconductor regrowth, resulting in epitaxial Al/Semiconductor/Al tri-layers on
low loss substrates.

*Laboratory of Physical Sciences, University of MD

–

Presenters

  • Anthony P McFadden

    • UCSB
    • Dept. of Electrical Engineering, Univ. of California, Santa Barbara, CA, USA
    • University of California, Santa Barbara
    • Univ of California, Santa Barbara

Authors

  • Anthony P McFadden

    • UCSB
    • Dept. of Electrical Engineering, Univ. of California, Santa Barbara, CA, USA
    • University of California, Santa Barbara
    • Univ of California, Santa Barbara

  • Corey Rae McRae

    • NIST Boulder / CU Boulder
    • NIST
    • National Institute of Standard and Technology Boulder
    • National Institute of Standards and Technology Boulder

  • RUICHEN ZHAO

    • National Institute of Standards and Technology Boulder
    • NIST
    • University of New South Wales

  • David Pappas

    • NIST Boulder
    • National Institute of Standards and Technology Boulder
    • NIST
    • National Institute of Standards and Technology
    • National Institute of Standard and Technology Boulder
    • National Institute of Standards and Technology - Boulder

  • Chris J Palmstrom

    • Materials Department, University of California, Santa Barbara
    • UCSB
    • Departments of Electrical and Computer Engineering and Materials, University of California, Santa Barbara
    • Dept. of Electrical Engineering, Univ. of California, Santa Barbara, CA, USA
    • Univ. of California, Santa Barbara
    • Electrical and Computer Engineering Department, University of California, Santa Barbara
    • University of California, Santa Barbara
    • IEE, UC Santa Barbara
    • University of California Santa Barbara
    • Univ of California, Santa Barbara
    • Electrical and Computer Engineering, University of California Santa Barbara
    • Materials and Electrical & Comp. Eng, University of California, Santa Barbara