Fault-tolerant spin-based quantum computers will require fast and accurate qubit read out. This can be achieved using radiofrequency 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 . 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 of integration time.
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Sensitive radiofrequency readout of quantum dots using an ultra-low-noise SQUID amplifier
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28 June 2020
Research Article|
June 29 2020
Sensitive radiofrequency readout of quantum dots using an ultra-low-noise SQUID amplifier
F. J. Schupp
;
F. J. Schupp
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
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F. Vigneau
;
F. Vigneau
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
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Y. Wen
;
Y. Wen
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
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A. Mavalankar;
A. Mavalankar
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
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J. Griffiths;
J. Griffiths
2
Cavendish Laboratory
, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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G. A. C. Jones;
G. A. C. Jones
2
Cavendish Laboratory
, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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I. Farrer
;
I. Farrer
2
Cavendish Laboratory
, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
3
Department of Electronic and Electrical Engineering, University of Sheffield
, Sheffield S1 3JD, United Kingdom
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D. A. Ritchie
;
D. A. Ritchie
2
Cavendish Laboratory
, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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C. G. Smith;
C. G. Smith
2
Cavendish Laboratory
, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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L. C. Camenzind;
L. C. Camenzind
4
Department of Physics, University of Basel
, 4056 Basel, Switzerland
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L. Yu;
L. Yu
4
Department of Physics, University of Basel
, 4056 Basel, Switzerland
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D. M. Zumbühl
;
D. M. Zumbühl
4
Department of Physics, University of Basel
, 4056 Basel, Switzerland
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G. A. D. Briggs
;
G. A. D. Briggs
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
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N. Ares
;
N. Ares
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
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E. A. Laird
E. A. Laird
a)
1
Department of Materials, University of Oxford
, 16 Parks Road, Oxford OX1 3PH, United Kingdom
5
Department of Physics, University of Lancaster
, Lancaster LA1 4YB, United Kingdom
a)Author to whom correspondence should be addressed: e.a.laird@lancaster.ac.uk
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a)Author to whom correspondence should be addressed: e.a.laird@lancaster.ac.uk
J. Appl. Phys. 127, 244503 (2020)
Article history
Received:
February 25 2020
Accepted:
June 14 2020
Connected Content
Citation
F. J. Schupp, F. Vigneau, Y. Wen, A. Mavalankar, J. Griffiths, G. A. C. Jones, I. Farrer, D. A. Ritchie, C. G. Smith, L. C. Camenzind, L. Yu, D. M. Zumbühl, G. A. D. Briggs, N. Ares, E. A. Laird; Sensitive radiofrequency readout of quantum dots using an ultra-low-noise SQUID amplifier. J. Appl. Phys. 28 June 2020; 127 (24): 244503. https://doi.org/10.1063/5.0005886
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