A step forward to miniaturizing “optical lattice clocks” Technique allowing high-precision portable clocks will open up new applications

July 11, 2014

A research group led by University of Tokyo Graduate School of Engineering Professor Hidetori Katori (Senior Researcher, RIKEN) has succeeded in high-precision spectroscopy of strontium atoms trapped inside a hollow-core photonic crystal fiber. This important achievement is a fundamental technique required for the miniaturization of quantum measuring devices.

© 2014Hidetoshi Katori.
Atoms lose coherence via interactions with each other and the walls of their environment, which degrades the performance of quantum metrology with atomic systems. As a route to minimize such effects, researchers used an optical lattice guided in a kagome-lattice hollow-core photonic crystal fiber to confine atoms without interacting with the fiber wall.

Currently, optical lattice clocks are being extensively studied all over the world as a leading candidate for the future “redefinition of the second.” The development of miniaturized and portable clocks are essential for their practical application. The research group confined laser-cooled strontium atoms inside a hollow-core fiber, and succeeded in high-precision spectroscopy of the trapped atoms. By trapping atoms in an optical lattice tuned to the magic wavelength inside the hollow-core fiber, the researchers prevented the equally-spaced atoms from colliding with each other and with the walls of the fiber, removing any interaction between atoms and without causing frequency shift due to the lattice confinement. Consequently, the researchers were able to observe the natural-linewidth-limited atomic spectrum inside the fiber.

These experiments demonstrate that use of a hollow-core fiber allows an increase the optical density of atoms while reducing atomic interactions. This technique will find broad applications in miniaturizing platforms for quantum metrology, including optical lattice clocks.

Press release

Press release (Japanese, JST)


Shoichi Okaba, Tetsushi Takano, Fetah Benabid, Tom Bradley, Luca Vincetti,Zakhar Maizelis, Valery Yampol’skii, Franco Nori & Hidetoshi Katori,
“Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre”,
Nature Communications Online Edition: 2014/6/17 (Japan time), doi: 10.1038/ncomms5096.
Article link (Publication, UTokyo Repository)


Graduate School of Engineering

Department of Applied Physics, Graduate School of Engineering

Katori Laboratory, Department of Applied Physics, Graduate School of Engineering

ERATO KATORI Innovative Space-Time Project

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