High-fidelity two-qubit gates for semiconductor quantum-dot spin qubits

• Project/Area Number: 17K14078
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Nanostructural physics
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Takeda Kenta 国立研究開発法人理化学研究所, 創発物性科学研究センター, 研究員 (80755877)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2017: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
• Keywords: 量子ドット / 量子ビット / 量子情報 / 量子コンピュータ

Outline of Final Research Achievements

Recent technical advances have enabled high-fidelity single-qubit gates (fidelity > 99.9%) for semiconductor quantum-dot spin qubits. In addition, to perform universal quantum operations, a two-qubit entangling gate is necessary. In this study, we perform implementation and characterization of two-spin control using a double-quantum-dot spin qubit. In order to control the two-spin state, it is necessary to utilize the exchange interaction between two spins. Unlike the single spin state that is only sensitive to the magnetic noise, the exchange interaction is sensitive to the electrical charge noise commonly present in the semiconductor material. Therefore, we designed our device and control scheme so that the exchange interaction becomes less sensitive to the charge noise in order to implement a high-fidelity spin control. We perform a randomized benchmarking measurement to evaluate the control fidelity of the singlet-triplet spin states and obtain a control fidelity of 99.6 %.

Academic Significance and Societal Importance of the Research Achievements

量子コンピュータは、量子力学的重ね合わせ状態を用いた超並列計算を可能とする次世代のコンピュータである。量子コンピュータの基本単位である量子ビットの物理的実装のために様々な系が研究されている。シリコンを用いた量子ドットは、半導体製造技術を適用した集積可能性から、有力な量子ビット系として考えられている。本研究では、２つのシリコン量子ドット中に閉じ込めた２電子状態を用いた量子ビットを実装した。量子ドットのパラメータを最適化することで、電気的雑音が量子ビットの情報保持時間（コヒーレンス時間）に与える影響を小さくし、十分高精度に量子ビットの操作が可能となることを示した。

Research Products

• [Journal Article] Resonantly Driven Singlet-Triplet Spin Qubit in Silicon (2020)
  • Author(s): Takeda K.、Noiri A.、Yoneda J.、Nakajima T.、Tarucha S.
  • Journal Title: Physical Review Letters Volume: 124 Issue: 11 Pages: 1-5
  • DOI: 10.1103/physrevlett.124.117701
  • Peer Reviewed
• [Journal Article] Quantum non-demolition readout of an electron spin in silicon (2020)
  • Author(s): Yoneda J.、Takeda K.、Noiri A.、Nakajima T.、Li S.、Kamioka J.、Kodera T.、Tarucha S.
  • Journal Title: Nature Communications Volume: 11 Issue: 1 Pages: 1-7
  • DOI: 10.1038/s41467-020-14818-8
  • Peer Reviewed / Open Access
• [Journal Article] Radio-Frequency-Detected Fast Charge Sensing in Undoped Silicon Quantum Dots (2020)
  • Author(s): Noiri Akito、Takeda Kenta、Yoneda Jun、Nakajima Takashi、Kodera Tetsuo、Tarucha Seigo
  • Journal Title: Nano Letters Volume: 20 Issue: 2 Pages: 947-952
  • DOI: 10.1021/acs.nanolett.9b03847
  • Peer Reviewed
• [Journal Article] Optimized electrical control of a Si/SiGe spin qubit in the presence of an induced frequency shift (2018)
  • Author(s): K. Takeda, J. Yoneda, T. Otsuka, T. Nakajima, M. R. Delbecq, G. Allison, Y. Hoshi, N. Usami, K. M. Itoh, S. Oda, T. Kodera and S. Tarucha
  • Journal Title: npj Quantum Information Volume: 4 Issue: 1 Pages: 54-54
  • DOI: 10.1038/s41534-018-0105-z
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9% (2018)
  • Author(s): Jun Yoneda, Kenta Takeda, Tomohiro Otsuka, Takashi Nakajima, Matthieu R. Delbecq, Giles Allison, Takumu Honda, Tetsuo Kodera, Shunri Oda, Yusuke Hoshi, Noritaka Usami, Kohei M. Itoh, and Seigo Tarucha
  • Journal Title: Nature Nanotechnology Volume: 13 Issue: 2 Pages: 102-106
  • DOI: 10.1038/s41565-017-0014-x
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Coherent manipulation of three-spin state in a Si/SiGe triple quantum dot (2020)
  • Author(s): K. Takeda, A. Noiri, T. Nakajima, J. Yoneda, T. Kobayashi, and S. Tarucha
  • Organizer: APS March meeting 2020
• [Presentation] High-fidelity resonant operation of a Si-based singlet-triplet qubit (2019)
  • Author(s): K. Takeda, A. Noiri, T. Nakajima, J. Yoneda, S. Li, and S. Tarucha
  • Organizer: Silicon quantum electronics workshop 2019
  • Int'l Joint Research
• [Presentation] Control fidelities in isotopically natural and enriched silicon quantum dot qubits (2018)
  • Author(s): K. Takeda, J. Yoneda, T. Otsuka, T. Nakajima, M. R. Delbecq1, 4 G. Allison1, A. Noiri, Y. Hoshi, N. Usami, K. M. Itoh, S. Oda, T. Kodera and S. Tarucha
  • Organizer: 2018 International Conference on Solid State Devices and Materials
  • Int'l Joint Research
• [Presentation] Control fidelities in isotopically natural and enriched silicon quantum dot qubits (2018)
  • Author(s): K. Takeda, J. Yoneda, T. Otsuka, T. Nakajima, M. R. Delbecq1, 4 G. Allison1, A. Noiri, Y. Hoshi, N. Usami, K. M. Itoh, S. Oda, T. Kodera and S. Tarucha
  • Organizer: 8TH SUMMER SCHOOL ON SEMICONDUCTOR/SUPERCONDUCTOR QUANTUM COHERENCE EFFECT AND QUANTUM INFORMATION
• [Presentation] Microwave induced frequency shift and its quadrature compensation for Si/SiGe spin qubits (2018)
  • Author(s): Kenta Takeda, Jun Yoneda, Tomohiro Otsuka, Takashi Nakajima, Matthieu R. Delbecq, Giles Allison, Jun Kamioka, Takumu Honda, Tetsuo Kodera, Shunri Oda, Yusuke Hoshi, Noritaka Usami, Kohei M. Itoh, and Seigo Tarucha
  • Organizer: International Workshop on Silicon Quantum Electronics
  • Int'l Joint Research
• [Presentation] シリコン量子ドットにおける２スピン同時検出 (2018)
  • Author(s): 米田淳、武田健太、野入亮人、中島峻、大塚朋廣、Sen Li、小寺哲夫、樽茶清悟
  • Organizer: 日本物理学会