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RIKEN Center for Emergent Matter Science Quantum Information Theory Research Team

Team Leader: Keisuke Fujii (Ph.D. (Eng.))

Research Summary

Keisuke Fujii (Ph.D. (Eng.))

We focus on quantum software engineering science, which is necessary for the realization of quantum computers. We will develop basic technologies to exploit the performance of quantum computers on a scale that is now being realized or will be realized in the next few years, as well as applications of them to fundamental physics, quantum chemistry, and quantum machine learning, and we will work on quantum computer architectures, quantum error correction, and optimization of quantum circuits to realize large scale fault-tolerant quantum computers. We are also interested in interdisciplinary fields between quantum information science and fundamental physics, quantum chemistry, machine learning, and high-performance computing.

Main Research Fields

  • Mathematical & Physical Sciences

Related Research Fields

  • Informatics
  • Atomic/Molecular/Quantum electronics
  • Theory of informatics
  • Mathematical physics/ Fundamental condensed matter physics


  • Quantum computing
  • Quantum information science
  • Quantum machine learning
  • Quantum many-body system

Selected Publications

Papers with an asterisk(*) are based on research conducted outside of RIKEN.

  • 1. *K. Mitarai, M. Negoro, M. Kitagawa, and K. Fujii.:
    "Quantum Circuit Learning"
    Phys. Rev. A, 98, 032309 (2018)
  • 2. *K. Fujii and K. Nakajima.:
    "Harnessing Disordered-Ensemble Quantum Dynamics for Machine Learning"
    Phys. Rev. Applied, 8, 24030 (2017)
  • 3. *K. Fujii, M. Negoro, N. Imoto, and M. Kitagawa.:
    "Measurement-Free Topological Protection Using Dissipative Feedback"
    Phys. Rev. X, 4, 041039 (2014)
  • 4. *K. Fujii, Y. Nakata, M. Ohzeki, M. Murao.:
    "Measurement-Based Quantum Computation on Symmetry Breaking Thermal States"
    Phys. Rev. Lett., 110, 120502 (2013)
  • 5. *K. Fujii and Y. Tokunaga.:
    "Fault-Tolerant Topological One-Way Quantum Computation with Probabilistic Two-Qubit Gates"
    Phys. Rev. Lett., 105, 250503 (2010)

Related Links

Lab Members

Principal investigator

Keisuke Fujii
Team Leader


Position Deadline
Seeking a Research Scientist or Senior Research Scientist or Postdoctoral Researcher (W20244) Open until filled

Contact Information

Bioscience Building(S01)
2-1 Hirosawa,
Wako-shi, Saitama
Email: keisuke.fujii.ay [at] riken.jp