Sensitive Radio-Frequency Measurements of a Quantum Dot by Tuning to Perfect Impedance Matching

N. Ares, F. J. Schupp, A. Mavalankar, G. Rogers, J. Griffiths, G. A. C. Jones, I. Farrer, D. A. Ritchie, C. G. Smith, A. Cottet, G. A. D. Briggs, and E. A. Laird
Phys. Rev. Applied 5, 034011 – Published 24 March 2016
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Abstract

Electrical readout of spin qubits requires fast and sensitive measurements, which are hindered by poor impedance matching to the device. We demonstrate perfect impedance matching in a radio-frequency readout circuit, using voltage-tunable varactors to cancel out parasitic capacitances. An optimized capacitance sensitivity of 1.6aF/Hz is achieved at a maximum source-drain bias of 170μV root-mean-square and with a bandwidth of 18 MHz. Coulomb blockade in a quantum-dot is measured in both conductance and capacitance, and the two contributions are found to be proportional as expected from a quasistatic tunneling model. We benchmark our results against the requirements for single-shot qubit readout using quantum capacitance, a goal that has so far been elusive.

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  • Received 30 November 2015

DOI:https://doi.org/10.1103/PhysRevApplied.5.034011

© 2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

N. Ares1, F. J. Schupp1, A. Mavalankar1, G. Rogers1, J. Griffiths2, G. A. C. Jones2, I. Farrer2, D. A. Ritchie2, C. G. Smith2, A. Cottet3, G. A. D. Briggs1, and E. A. Laird1

  • 1Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
  • 2Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
  • 3Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France

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Vol. 5, Iss. 3 — March 2016

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