Measurements of dc SQUID backaction noise in the MHz range

ORAL

Abstract

DC SQUIDs are a well established and sensitive technology to probe magnetic flux and current signals in the MHz range. Despite their widespread use, there is a lack of measurements of DC SQUID backaction noise, as well as of correlations between imprecision and backaction, in this frequency range which are an important factor for axion searches like DMRadio. In this talk, I will present measurements of DC SQUID backaction noise and imprecision/backaction correlations at MHz frequencies. This is done by means of coupling a high Q resonator in a dilution refrigerator to a DC SQUID via a tunable transformer. The tunable transformer allows in situ variation of the SQUID-resonator coupling strength and hence allows probing the strength of the backaction noise sourced by the amplifier. I will outline the design of the experiment and present noise data with both tuned coupling and temperature. I will also discuss implications for experiments that use DC SQUIDs such as lumped element axion searches.

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Presenters

  • Jyotirmai Singh

    • Stanford University

Authors

  • Jyotirmai Singh

    • Stanford University

  • Christina Bell

    • Stanford University

  • Victoria Ankel

    • Stanford University

  • Chelsea L Bartram

    • Stanford University / SLAC National Accelerator Laboratory
    • SLAC National Accelerator Laboratory

  • Hsiao-Mei Cho

    • SLAC National Accelerator Laboratory

  • Jason Young Ho Corbin

    • Stanford University

  • Ameya Kunder

    • Stanford University

  • Nicholas M Rapidis

    • Stanford University

  • Chiara P Salemi

    • Stanford University
    • UC Berkeley/LBNL

  • Maria Simanovskaia

    • Stanford University

  • Elizabeth C van Assendelft

    • Stanford University

  • Dean Wright

    • Stanford University

  • Kent D Irwin

    • Stanford University