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

Ares, N and Schupp, F J and Mavalankar, A and Rogers, G and Griffiths, J P and Jones, G A C and Farrer, I and Ritchie, D. A. and Smith, C G and Cottet, A and Briggs, G A D and Laird, E A (2016) Sensitive Radio-Frequency Measurements of a Quantum Dot by Tuning to Perfect Impedance Matching. Physical Review Applied, 5. ISSN 2331-7019

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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 1.6  aF/√Hz is achieved at a maximum source-drain bias of 170−μV 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.

Item Type: Journal Article
Journal or Publication Title: Physical Review Applied
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/3100
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 124385
Deposited By: ep_importer_pure
Deposited On: 04 Apr 2018 15:34
Refereed?: Yes
Published?: Published
Last Modified: 23 Oct 2019 06:24
URI: https://eprints.lancs.ac.uk/id/eprint/124385

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