Analytical Calculation of Gain and Noise of DC Squid Microwave Amplifier

ORAL

Abstract

The dc SQUID microwave amplifier, based on Josephson junctions, is employed in a wide spectrum of applications ranging from dark matter detection to the readout of superconducting qubits. A crucial advantage offered by this device is the separation of input and output channels, unlike conventional Josephson parametric amplifiers, so that it does not require a nonreciprocal device such as a circulator for its operation. The mechanism underlying the directional gain in the SQUID microwave amplifier, however, has so far remained elusive. We present a first principles, analytical calculation, based on scattering theory, of a practical SQUID amplifier which elucidates the underlying nonlinear mode mixing responsible for the directional operation of the device. The gain and quantum noise characteristics of a SQUID operated as a microwave voltage amplifier are discussed. Work supported by IARPA and ARO (AK, MHD and JC) and NSF (AK and MHD).

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Authors

  • Archana Kamal

    Yale University, Applied Physics, Yale University, Departments of Physics and Applied Physics, Yale University, Applied Physics - Yale University

  • Michel Devoret

    Yale University, Applied Physics, Yale University, Applied Physics Department Yale University, Department of Applied Physics, Yale University, Departments of Physics and Applied Physics, Yale University, Applied Physics - Yale University, Yale University, Dept. of Applied Physics, Applied Physics Dept. Yale University

  • John Clarke

    University of California, Berkeley, UC Berkeley, Department of Physics, University of California, Berkeley