Suppression of 1/f Flux Noise in Superconducting Quantum Circuits

ORAL

Abstract

Low frequency 1/f magnetic flux noise is a dominant contributor to dephasing in superconducting quantum circuits. It is believed that the noise is due to a high density of unpaired magnetic defect states at the surface of the superconducting thin films. We have performed X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) experiments that point to adsorbed molecular oxygen as the dominant source of magnetism in these films. By improving the vacuum environment of our superconducting devices, we have achieved a significant reduction in surface magnetic susceptibility and 1/f flux noise power spectral density. These results open the door to realization of superconducting qubits with improved dephasing times.

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Authors

  • Pradeep Kumar

    University of Wisconsin, Madison

  • John Freeland

    Advanced Photon Source, Argonne National Lab, Argonne, IL, Advanced Photon Source, Argonne National Laboratory, Argonne National Lab, Argonne National Laboratory, APS, Argonne National Laboratory

  • Clare Yu

    Department of Physics and Astronomy, University of California, Irvine, CA

  • Ruqian Wu

    Department of Physics and Astronomy, University of California, Irvine, CA, Dept. of Physics and Astronomy, University of California, UCI, Department of Physics and Astronomy, University of California, Department of Physics and Astronomy, University of California, Irvine, Dept. of Physics and Astronomy, Univ. of California

  • Zhe Wang

    State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China

  • Hui Wang

    Department of Physics and Astronomy, University of California, Irvine, CA

  • Chuntai Shi

    Department of Physics and Astronomy, University of California, Irvine, CA

  • David Pappas

    National Institute of Standards and Technology, Boulder, CO, NIST-Boulder

  • R. F. McDermott

    University of Wisconsin, Madison, University of Wisconsin--Madison, University of Wisconsin