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RIKEN Center for Advanced Photonics Space-Time Engineering Research Team

Team Leader: Hidetoshi Katori (D.Eng.)

Research Summary

Hidetoshi  Katori(D.Eng.)

Clocks have served as a tool to share time, based on universal periodic phenomena; humankind relied upon the rotation of the earth from antiquity. The radiation from an atom provides us with far more accurate periodicity. The state-of-the-art atomic clocks sense the relativistic space-time curved by gravity, which reveal the difficulty of sharing time with others. Moreover, such clocks may be used to investigate the constancy of fundamental constants, where the foundation of the atomic clocks is anchored.

Optical lattice clocks raised the possibility of ultra-stable and accurate timekeeping by applying the "magic wavelength" protocol on optical lattices. Since the proposal of the scheme in 2001, the optical lattice clocks are being developed by more than 20 groups in the world, and the clocks are surpassing the uncertainty of the current SI second, becoming one of the most promising candidates for the future redefinition of the second.

Our team develops highly precise and transportable optical lattice clocks capable of long time operation by introducing advanced techniques in the field of atomic physics and quantum optics; we thus explore applications of "space-time engineering" that fully utilize the novel time resource provided by such clocks. For example, a transportable ultraprecise atomic clock, which may be taken out into the field, will function as a gravitational potential meter. We experimentally investigate the impact of such relativistic geodesy as a newer role for clocks in the future.

Main Research Fields

  • Interdisciplinary Science & Engineering

Related Research Fields

  • Engineering


  • Quantum electronics
  • Atomic clock
  • Quantum metrology
  • Optical lattice clock
  • Relativistic geodesy

Selected Publications

  • 1.Tetsushi Takano, Masao Takamoto, Ichiro Ushijima, Noriaki Ohmae, Tomoya Akatsuka, Atsushi Yamaguchi, Yuki Kuroishi, Hiroshi Munekane, Basara Miyahara, and Hidetoshi Katori:
    "Geopotential measurements with synchronously linked optical lattice clocks"
    Nat. Photonics. 10, 662 (2016).
  • 2.Nils Nemitz, Takuya Ohkubo, Masao Takamoto, Ichiro Ushijima, Manoj Das, Noriaki Ohmae and Hidetoshi Katori:
    "Frequency ratio of Yb and Sr clocks with 5×10-17 uncertainty at 150 seconds averaging time"
    Nat. Photonics. 10, 258-261 (2016).
  • 3.Kazuhiro Yamanaka, Noriaki Ohmae, Ichiro Ushijima, Masao Takamoto, and Hidetoshi Katori:
    "Frequency Ratio of199Hg and87Sr Optical Lattice Clocks beyond the SI Limit"
    Phys. Rev. Lett. 114,230801 (2015).
  • 4.Ushijima, I., Takamoto, M., Das, M., Ohkubo, T. and Katori, H.:
    "Cryogenic optical lattice clocks"
    Nat. Photonics, doi:410.1038/nphoton.2015.5 (2015).
  • 5.Hidetoshi Katori:
    "Optical lattice clocks and quantum metrology"
    Nat. Photonics. 5, 203-210 (2011)
  • 6.Masao Takamoto, Tetsushi Takano, and Hidetoshi Katori:
    "Frequency comparison of optical lattice clocks beyond the Dick limit"
    Nat. Photonics. 5, 288-292 (2011)
  • 7.M. Takamoto, H. Katori, S. I. Marmo, V. D. Ovsiannikov, and V. G. Pal'chikov:
    "Prospects for Optical Clocks with a Blue-Detuned Lattice"
    Phys. Rev. Lett. 102, 063002 (2009)
  • 8.Tomoya Akatsuka, Masao Takamoto, and Hidetoshi Katori:
    "Optical lattice clocks with non-interacting bosons and fermions"
    Nat. Phys. 4, 954-959 (2008)
  • 9.M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori:
    "An optical lattice clock"
    Nature 435, 321-324 (2005)
  • 10.Hidetoshi Katori, Masao Takamoto, V. G. Pal'chikov, and V. D. Ovsiannikov:
    "Ultrastable Optical Clock with Neutral Atoms in an Engineered Light Shift Trap"
    Phys. Rev. Lett. 91, 173005 (2003)

Recent Research Results

Related Links

Lab Members

Principal investigator

Hidetoshi Katori
Team Leader

Core members

Masao Takamoto
Senior Research Scientist
Noriaki Ohmae
Research Scientist
Atsushi Yamaguchi
Research Scientist
Shoichi Okaba
Special Postdoctoral Researcher
Andrew George Hinton
Special Postdoctoral Researcher
Akiko Gomyo
Visiting Scientist

Contact Information

Cooperation Center, W421
2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Email: hkatori [at] riken.jp