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Electrical control of a solid-state flying qubit

Nature Nanotechnology volume 7, pages 247–251 (2012)Cite this article

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Abstract

Solid-state approaches to quantum information technology are attractive because they are scalable. The coherent transport of quantum information over large distances is a requirement for any practical quantum computer and has been demonstrated by coupling super-conducting qubits to photons1. Single electrons have also been transferred between distant quantum dots in times shorter than their spin coherence time2,3. However, until now, there have been no demonstrations of scalable ‘flying qubit’ architectures—systems in which it is possible to perform quantum operations on qubits while they are being coherently transferred—in solid-state systems. These architectures allow for control over qubit separation and for non-local entanglement, which makes them more amenable to integration and scaling than static qubit approaches. Here, we report the transport and manipulation of qubits over distances of 6 µm within 40 ps, in an Aharonov–Bohm ring connected to two-channel wires that have a tunable tunnel coupling between channels. The flying qubit state is defined by the presence of a travelling electron in either channel of the wire, and can be controlled without a magnetic field. Our device has shorter quantum gates (<1 µm), longer coherence lengths (∼86 µm at 70 mK) and higher operating frequencies (∼100 GHz) than other solid-state implementations of flying qubits4,5.

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Figure 1: Device image and observed conventional AB oscillation.
Figure 2: Demonstration of Rx operation.
Figure 3: Demonstration of Rz operation.
Figure 4: Evaluation of coherence length lϕ.

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Acknowledgements

The authors thank B. Halperin for discussions. M.Y. acknowledges financial support from a Grant-in-Aid for Young Scientists A (no. 20684011). S. Takada acknowledges support from JSPS Research Fellowships for Young Scientists. S.Tarucha acknowledges financial support from Grants-in-Aid for Scientific Research S (no. 19104007) and B (no. 18340081), a MEXT Project for Developing Innovation Systems, MEXT KAKENHHI ‘Quantum Cybernetics’ and JST Strategic International Cooperative Program, Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST). A.D.W. acknowledges expert help from PD D. Reuter and support of the DFG SPP1285 and BMBF QuaHLRep 01BQ1035. C.B. acknowledges financial support from CNRS (DREI)–JSPS (nos PRC 424 and L08519).

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Authors and Affiliations

  1. Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan

    Michihisa Yamamoto, Shintaro Takada, Christopher Bäuerle, Kenta Watanabe & Seigo Tarucha

  2. ERATO-JST, Kawaguchi-shi, Saitama, 331-0012, Japan

    Michihisa Yamamoto

  3. Institut Néel – CNRS and Université Joseph Fourier, Grenoble, 38042, France

    Christopher Bäuerle

  4. Chair of Applied Solid-State Physics, Ruhr-Universität Bochum, Bochum, D-44780, Germany

    Andreas D. Wieck

  5. ICORP (International Cooperative Research Project) Quantum Spin Information Project, Atsugi-shi, Kanagawa, 243-0198, Japan

    Seigo Tarucha

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  1. Michihisa Yamamoto
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Contributions

M.Y. conceived the experiments, performed part of the experiments, interpreted the data and wrote the manuscript with C.B. and S. Tarucha. S. Takada fabricated the samples and conducted measurements and analysis. C.B. contributed to the experimental set-up and interpretation of the data. K.W. performed the experiments on decoherence with S. Takada. S. Takada, K.W. and C.B. carried out the high visibility measurements in Grenoble as presented in the Supplementary Information. A.D.W. provided the high-mobility heterostructures. S. Tarucha directed the research. All authors discussed the results and the manuscript extensively.

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Correspondence to Michihisa Yamamoto.

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Yamamoto, M., Takada, S., Bäuerle, C. et al. Electrical control of a solid-state flying qubit. Nature Nanotech 7, 247–251 (2012). https://doi.org/10.1038/nnano.2012.28

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