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    Rights statement: Copyright 2020 American Institute of Physics. The following article appeared in Journal of Applied Physics, 127, 2020 and may be found at https://doi.org/10.1063/5.0005886 This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

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Sensitive radio-frequency read-out of quantum dots using an ultra-low-noise SQUID amplifier

Research output: Contribution to journalJournal article

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  • F J Schupp
  • F. Vigneau
  • Yutian Wen
  • A Mavalankar
  • J. P. Griffiths
  • G. A. C. Jones
  • I. Farrer
  • David Ritchie
  • C. G. Smith
  • L. C. Camenzind
  • L. Yu
  • Dominik Zumbühl
  • G. Andrew D. Briggs
  • Edward Laird
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Article number244503
<mark>Journal publication date</mark>29/06/2020
<mark>Journal</mark>Journal of Applied Physics
Volume127
Number of pages9
Publication StatusPublished
<mark>Original language</mark>English

Abstract

Fault-tolerant spin-based quantum computers will require fast and accurate qubit readout. This can be achieved using radio-frequency reflectometry given sufficient sensitivity to the change in quantum capacitance associated with the qubit states. Here, we demonstrate a 23-fold improvement in capacitance sensitivity by supplementing a cryogenic semiconductor amplifier with a SQUID preamplifier. The SQUID amplifier operates at a frequency near 200 MHz and achieves a noise temperature below 600 mK when integrated into a reflectometry circuit, which is within a factor 120 of the quantum limit. It enables a record sensitivity to capacitance of 0.07 aF/ \sqrt{Hz}. The setup is used to acquire charge stability diagrams of a gate-defined double quantum dot in a short time with a signal-to-noise ration of about 38 in 1 μs of integration time.

Bibliographic note

Copyright 2020 American Institute of Physics. The following article appeared in Journal of Applied Physics, 127, 2020 and may be found at https://doi.org/10.1063/5.0005886 This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.