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.