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JST Press Release

June 17, 2014
Japan Science and Technology Agency (JST)
5-3, Yonbancho, Chiyoda-ku, Tokyo 102-8666
URL http://www.jst.go.jp/EN/index.html

A step forward to miniaturizing “optical lattice clocks”
A technique allowing high-precision portable-clocks will open up clocks’ new applications in the future.

As part of the JST Targeted Basic Research Program, Research group of the University of Tokyo has succeeded in high-precision spectroscopy of strontium atoms trapped inside a hollow-core photonic crystal fiber. This is an important achievement toward miniaturization of quantum devices.

Currently, optical lattice clocks have been extensively studied all over the world as a leading candidate for the future "redefinition of the second." For their practical use, miniaturized portable clocks are pursued. The research group confined laser-cooled strontium atoms inside a hollow-core fiber, and has succeeded in high-precision spectroscopy. By trapping atoms in an optical lattice tuned to the magic condition inside the hollow-core fiber, the researchers prevent atoms from colliding each other and with fiber walls, without causing frequency shift due to the lattice confinement.

Consequently, they observed natural-linewidth-limited atomic spectrum inside the fiber. Their experiments demonstrate that use of a hollow-core fiber allows to increase the optical density of atoms while reducing atomic interactions. The technique will find broad applications in miniaturizing platforms for quantum metrology, including optical lattice clocks.


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 use an optical lattice guided in a kagome-lattice hollow-core photonic crystal fiber to confine atoms without interacting with the fiber wall.

Researcher Information

The Exploratory Research for Advanced Technology (ERATO)
“Katori Innovative Space-Time Project”

Journal Information

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, 2014
doi: 10.1038/ncomms5096


[About Research]
Hidetoshi Katori Ph.D.,
Professor, Department of Applied Physics, Graduate School of Engineering,
The University of Tokyo
Chief Scientist, Quantum Metrology Laboratory, Advanced Science Institute, RIKEN
HP: http://www.jst.go.jp/erato/katori/erato_en/index.html

[About Program]
Department of Research Project, Japan Science and Technology Agency (JST),


JST, an integrated organization of science and technology in Japan, establishes an infrastructure for the entire process from the creation of knowledge to the return to the society. For more information, visit http://www.jst.go.jp/EN/