Rapid gate-based spin read-out in silicon using an on-chip resonator

Silicon spin qubits are one of the leading platforms for quantum computation1,2. As with any qubit implementation, a crucial requirement is the ability to measure individual quantum states

rapidly and with high fidelity. Since the signal from a single electron spin is minute, the different spin states are converted to different charge states3,4. Charge detection, so far, has

mostly relied on external electrometers5,6,7, which hinders scaling to two-dimensional spin qubit arrays2,8,9. Alternatively, gate-based dispersive read-out based on off-chip lumped element

resonators has been demonstrated10,11,12,13, but integration times of 0.2–2 ms were required to achieve single-shot read-out14,15,16. Here, we connect an on-chip superconducting resonant

circuit to two of the gates that confine electrons in a double quantum dot. Measurement of the power transmitted through a feedline coupled to the resonator probes the charge susceptibility,

distinguishing whether or not an electron can oscillate between the dots in response to the probe power. With this approach, we achieve a signal-to-noise ratio of about six within an

integration time of only 1 μs. Using Pauli’s exclusion principle for spin-to-charge conversion, we demonstrate single-shot read-out of a two-electron spin state with an average fidelity of

>98% in 6 μs. This result may form the basis of frequency-multiplexed read-out in dense spin qubit systems without external electrometers, therefore simplifying the system architecture.

The data reported in this paper are archived at https://doi.org/10.4121/uuid:8df1a6fa-9230-400f-a790-1b7714b1aad5.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Zwanenburg, F. A. et al. Silicon quantum electronics. Rev. Mod. Phys. 85, 961 (2013).

The authors thank T.F. Watson, J.P. Dehollain, P. Harvey-Collard, U.C. Mendes, B. Hensen and other members of the spin qubit team at QuTech for useful discussions, L.P. Kouwenhoven and his

team for access to NbTiN films, and P. Eendebak and L. Blom for software support. This research was undertaken thanks in part to funding from the European Research Council (ERC Synergy

Quantum Computer Lab), the Netherlands Organisation for Scientific Research (NWO/OCW) as part of the Frontiers of Nanoscience (NanoFront) programme and Intel Corporation.

QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands

Guoji Zheng, Nodar Samkharadze, Marc L. Noordam, Nima Kalhor, Giordano Scappucci & Lieven M. K. Vandersypen

QuTech and Netherlands Organization for Applied Scientific Research (TNO), Delft, The Netherlands

G.Z., N.S. and L.M.K.V. conceived and planned the experiments. G.Z. and M.L.N. carried out the experiments. A.S. grew the heterostructure with G.S.’s supervision. N.S. designed and

fabricated the device. D.B. and N.K. contributed to sample fabrication. G.Z., M.L.N. and L.M.K.V. analysed the results. G.Z. and L.M.K.V. wrote the manuscript with input from all co-authors.

L.M.K.V. supervised the project.

Peer review information: Nature Nanotechnology thanks Hongwen Jiang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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