Stabilizing a SQUID-based amplifier in high magnetic fields

ORAL

Abstract

dc SQUID-based circuits, when connected to sources exposed to strong magnetic fields, are often unstable in their fluxed-locked mode. We present a low noise SQUID-based current amplifier, which is unconditionally stable with a source exposed to magnetic fields up to 10 T.
Stability is achieved by inserting a four-pole low-pass filter between the source and the current
amplifier. With this circuit, we demonstrate Johnson noise measurements below 1 K for source
impedances in the kΩ range subjected to strong magnetic fields. We also discuss preliminary
high-resolution thermal transport data in a two-dimensional electron gas confined in GaAs/AlGaAs.

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Presenters

  • Vidhi Shingla

    Purdue University

Authors

  • Vidhi Shingla

    Purdue University

  • Ethan Kleinbaum

    Electrical Engineering, Princeton University

  • Loren Pfeiffer

    Electrical Engineering, Princeton University, Princeton University, Princeton Univ, Department of Electrical Engineering, Princeton University, PRISM, Princeton University, Physics, Princeton University, Electrical Engineering, Princeton

  • Kenneth West

    Electrical Engineering, Princeton University, Princeton University, Princeton Univ, Department of Electrical Engineering, Princeton University, PRISM, Princeton University, Physics, University of Pittsburgh, Electrical Engineering, Princeton

  • Gabor Csathy

    Purdue University