Centers & Labs

RIKEN Center for Advanced Photonics

Space-Time Engineering Research Team

Team Leader: Hidetoshi Katori (D.Eng.)
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 Field

Interdisciplinary science and engineering

Related Research Fields


Research Subjects

  • Development of optical lattice clocks with superb precision
  • Investigation of the constancy of fundamental constants using atomic clocks
  • Development of gravitational potential meter using high precision clocks
  • Exploratory research on relativistic geodesy

Selected Publications

  1. Ushijima, I., Takamoto, M., Das, M., Ohkubo, T. and Katori, H.:
    "Cryogenic optical lattice clocks"
    Nature Photonics, doi:410.1038/nphoton.2015.5 (2015).
  2. Hidetoshi Katori:
    "Optical lattice clocks and quantum metrology"
    Nature Photon 5, 203-210 (2011)
  3. Masao Takamoto, Tetsushi Takano, and Hidetoshi Katori:
    "Frequency comparison of optical lattice clocks beyond the Dick limit"
    Nature Photon. 5, 288-292 (2011)
  4. H. Katori, K. Hashiguchi, E. Yu. Il'inova, V. D. Ovsiannikov:
    "Magic Wavelength to Make Optical Lattice Clocks Insensitive to Atomic Motion"
    Phys. Rev. Lett. 103, 153004 (2009)
  5. 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)
  6. Tomoya Akatsuka, Masao Takamoto, and Hidetoshi Katori:
    " Optical lattice clocks with non-interacting bosons and fermions "
    Nat. Phys. 4, 954-959 (2008)
  7. H. Hachisu, K. Miyagishi, S. G. Porsev, A. Derevianko, V. D. Ovsiannikov, V. G. Pal'chikov, M. Takamoto, and H. Katori:
    "Trapping of Neutral Mercury Atoms and Prospects for Optical Lattice Clocks"
    Phys. Rev. Lett. 100, 053001 (2008)
  8. M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori:
    "An optical lattice clock"
    Nature 435, 321-324 (2005)
  9. Masao Takamoto and Hidetoshi Katori,
    "Spectroscopy of the 1S0-3P0 Clock Transition of 87Sr in an Optical Lattice"
    Phys. Rev. Lett. 91, 223001 (2003)
  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)

Lab Members

Principal Investigator

Hidetoshi Katori
Team Leader

Core Members

Masao Takamoto
Senior Research Scientist
Nils Nemitz
Research Scientist
Atsushi Yamaguchi
Research Scientist
Ichiro Ushijima
Postdoctoral Researcher
Manoj Das
Postdoctoral Researcher
Shoichi Okaba
Special Postdoctoral Researcher

Contact information

Cooperation Center, W421
2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Email: hkatori [at]

Related links

Recent research results