Microwave amplifier based on an inline dc SQUID

ORAL

Abstract

The dc SQUID can be used as a sensitive, low-noise microwave amplifier if the signal to be amplified is suitably coupled to the SQUID. We have designed and fabricated microwave amplifiers based on inline dc SQUIDs, where the SQUID loop is formed from a thin ($\sim$ 100 nm) dielectric layer separating the base and counterelectrode wiring traces. The SQUID is embedded in a microstrip transmission line resonator at a current anti-node, and signal current is injected directly into the SQUID loop. With this design we have achieved gain greater than 20 dB at a frequency of 8.5 GHz. We provide a theoretical analysis of amplifier noise temperature, bandwidth, and gain, and describe measurements of amplifier noise temperature. We discuss application of these devices to the readout of superconducting quantum circuits.

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Authors

  • David Hover

    • University of Wisconsin

  • Y.-F. Chen

    • University of Wisconsin

  • Leon Maher

    • University of Wisconsin

  • Guilhem Ribeill

    • University of Wisconsin

  • Shao-Jiang Zhu

    • University of Wisconsin

  • Steve Sendelbach

    • University of Wisconsin

  • Robert McDermott

    • University of Wisconsin--Madison
    • UW-Madison Department of Physics
    • University of Wisconsin