Using Atomic Layer Deposition for Josephson Junction Quantum Bits

ORAL

Abstract

Ultrathin dielectric tunneling barriers are critical to Josephson junction (JJ) based superconducting quantum bits (qubits). However, the prevailing technique of thermally oxidizing aluminum via oxygen diffusion produces problematic point defects, such as oxygen vacancies, which are believed to be a primary source of the two-level fluctuators that contribute to the decoherence of the qubits. Atomic Layer Deposition (ALD) of aluminum oxide (Al$_{2}$O$_{3})$ is a promising alternative to resolve the issue of oxygen vacancies in the Al$_{2}$O$_{3\, }$tunneling barrier, and its self-limiting growth mechanism provides atomic-scale precision in tunneling barrier thickness control. ALD has been implemented in a high-vacuum magnetron sputtering system for \textit{in situ} deposition of ALD-Al$_{2}$O$_{3}$ tunneling barriers in superconductor-insulator-superconductor (SIS) JJs. The modifications made to the Al surface during ALD were explored with ellipsometry and atomic force microscopy, and ALD-Al$_{2}$O$_{3}$ barriers were grown on Nb to form Nb/Al2O3/Nb JJs. Preliminary low temperature measurements of current-voltage characteristics of the Josephson junctions made from these trilayers confirmed the integrity of the ALD-Al$_{2}$O$_{3}$ barrier layer.

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Authors

  • Alan Elliot

    University of Kansas Dept. of Physics \& Astronomy

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa

  • Jatinder Kumar

    Harvard U., Baker University, Bejing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Northrop Grumman, Baltimore, MD, University of Kansas Dept. of Physics \& Astronomy, Kansas State University, Department of Chemistry, College of Materials Science \& Engineering, Sichuan University, China, Illinois State University, Mullard Space Science Laboratory, University College of London, Holmbury St. Mary, United Kingdom, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, United States, Weizmann Institute of Science, Rehovot, Israel, Monmouth College, Missouri State University, Birla Institute of Technology and Science, University of Illinois at Urbana Champaign, Ames Laboratory. Department of Physics and Astronomy, Iowa State University, Siena College, \'Ecole Polytechnique F\'ed\'erale de Lausanne, Switzerland, Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Kansas State University, Purdue University, Princeton University, Oklahoma State University, University of Chicago, University of Iowa, University of Kansas, University of Kansas and University of Iowa