Semiconductor Quantum Information Device Research Team

Principal Investigator

PI Name Seigo Tarucha
Degree D.Eng.
Title Team Leader
Brief Resume
1978Staff Member at the Basic Research Laboratories of Nippon Tel. & Tel. Corp.
1985Senior Researcher at the Basic Research Laboratories of Nippon Tel. & Tel. Corp.
1986Visiting Scientist, Max-Planck-Institute FKF (Stuttgart, Germany)(-1987)
1989Principal Researcher at the Basic Research Laboratories of Nippon Tel. & Tel. Corp.
1990Group Leader, Research Group on Electron Transport in Low-Dimensional Semiconductor Structures, NTT Basic Research Laboratories(-1998)
1994Distinguished Scientist, NTT Basic Research Laboratories (-1998)
1995Visiting Professor, Technical University of Delft (The Netherlands)
1998Professor, Department of Physics, University of Tokyo (-2004)
2004Professor, Department of Applied Physics, University of Tokyo (-2018)
2012Visiting Professor, Institut Néel CNRS, université Joseph Fourier (France)
2013Division Director, Quantum Information Electronics Division, RIKEN Center for Emergent Matter Science (-present)
2013Group Director, Quantum Functional System Research Group, RIKEN Center for Emergent Matter Science (-present)
2018Deputy Director, RIKEN Center for Emergent Matter Science (-present)
2019Guest Professor, Department of Physics, Tokyo University of Science (-present)
2020Team Leader, Semiconductor Quantum Information Device Research Team, RIKEN Center for Emergent Matter Science (-present)


We perform research and development of electron (or hole) spin based quantum computing with silicon quantum dots. Study on silicon quantum computing has been motivated by advantages of compatibility with existing semiconductor device integration technology and capability of high-temperature (> 1 Kelvin) operation. We demonstrate that manipulation of quantum coherence and entanglement of silicon spin qubits in semiconductor nanostructures and superconducting nano-scale junctions is useful as elemental technology of information processing and develop relevant quantum logic calculation methods, advanced quantum architectures, qubit devices having compatibility with integration technology.

Research Fields

Physics, Engineering


Quantum computer
Quantum dots
Quantum devices
Spin control


Realization of high-accuracy two-spin exchange operation for spin qubits in silicon

Silicon quantum computer which utilizes electron spin in quantum dots is expected to suit implementation of large-scale quantum computer, because it has the huge head start of being able to operate at high temperature (>1K) and apply the semiconductor manufacturing techniques used for conventional electronics.

To execute quantum computing it is necessary to operate not only single qubits but also two qubits. To date high-accuracy qubit operation has been demonstrated for single spins but not yet for two spins. This is because of influences from electrical noise arising from charge impurities. 

We have realized high-accuracy two-spin operation using a qubit that employs the spins of two electrons (| > and | >) in a silicon double quantum dot (Fig. A). We have developed a new method to minimize the influence from the electrical noise and achieved spin exchange operation with 99.6% accuracy, the highest ever reported (Fig. B).

Fig. A Electron micrograph of the Si triple quantum dot device. The double quantum dot in red and blue is used for experiment.
Fig. B Rabi oscillation measured for the exchange of the two two-spin states, |↑↓> and |↓↑>.


Seigo Tarucha

Team Leader tarucha[at] R


  1. K. Takeda, A. Noiri, J. Yoneda, T. Nakajima, and S. Tarucha

    Resonantly Driven Singlet-Triplet Spin Qubit in Silicon

    Phys. Rev. Lett. 124, 117701 (2020)
  2. A. Noiri, K. Takeda, J. Yoneda, T. Nakajima, T. Kodera, and S. Tarucha

    Radio-Frequency-Detected Fast Charge Sensing in Undoped Silicon Quantum Dots

    Nano Lett. 20, 947 (2020)
  3. J. Yoneda, K. Takeda, T. Otsuka, T. Nakajima, M. R. Delbecq, G. Allison, T. Honda, T. Kodera, S. Oda, Y. Hoshi, N. Usami, K. M. Itoh, and S. Tarucha

    A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%

    Nat. Nanotechnol. 13, 102 (2018)
  4. T. Nakajima, M. R. Delbecq, T. Otsuka, P. Stano, S. Amaha, J. Yoneda, A. Noiri, K. Kawasaki, K. Takeda, G. Allison, A. Ludwig, A. D. Wieck, D. Loss, and S. Tarucha

    Robust Single-Shot Spin Measurement with 99.5% Fidelity in a Quantum Dot Array

    Phys. Rev. Lett. 119, 017701 (2017)
  5. K. Takeda, J. Kamioka, T. Otsuka, J. Yoneda, T. Nakajima, M. R. Delbecq, S. Amaha, G. Allison, T. Kodera, S. Oda, and S. Tarucha

    A fault-tolerant addressable spin qubit in a natural silicon quantum dot

    Sci. Adv. 2, 1600694 (2016)


2-1 Hirosawa, Wako, Saitama 351-0198 Japan