activity
20142025
most citedSearch for ultralight dark matter from long-term frequency comparisons of optical and microwave atomic clocks

68 citations · 305 across the 14 of their papers we have counts for

collaborators

14 papers

physics.atom-ph2025★ 2 cited

Improved absolute frequency measurement of Yb at NMIJ with uncertainty below

Takumi Kobayashi, Akiko Nishiyama, Kazumoto Hosaka +6

We report improved absolute frequency measurement of the SP transition of Yb at National Metrology Institute of Japan (NMIJ) by comparing the $^{171}…

physics.atom-ph2024★ 9 cited

Generation of a precise time scale assisted by a near-continuously operating optical lattice clock

Takumi Kobayashi, Daisuke Akamatsu, Kazumoto Hosaka +8

We report on a reduced time variation of a time scale with respect to Coordinated Universal Time (UTC) by steering a hydrogen-maser-based time scale with a near-continuously operat…

physics.atom-ph2024★ 6 cited

Isotope-shift analysis with the transition in ytterbium

Akio Kawasaki, Takumi Kobayashi, Akiko Nishiyama +2

Measurements of isotope shifts have recently been attracting considerable attention due to their potentials in searching for new forces. We report on the isotope shifts of the $4f^…

physics.atom-ph2023★ 6 cited

Observation of the clock transition at 431 nm in Yb

Akio Kawasaki, Takumi Kobayashi, Akiko Nishiyama +2

We report on the observation of the transition at 431 nm in Yb by depleting atoms in a magneto-optical trap formed by the $6s^{2…

physics.atom-ph2022★ 68 cited

Search for ultralight dark matter from long-term frequency comparisons of optical and microwave atomic clocks

Takumi Kobayashi, Akifumi Takamizawa, Daisuke Akamatsu +8

We search for ultralight scalar dark matter candidates that induce oscillations of the fine structure constant, the electron and quark masses, and the quantum chromodynamics energy…

eess.SP2020★ 8 cited

Potential for improving the local realization of coordinated universal time with a convolutional neural network

Takehiko Tanabe, Jiaxing Ye, Tomonari Suzuyama +3

The time difference between coordinated universal time (UTC) and a hydrogen maser, which is a master oscillator for the local realization of UTC at the National Metrology Institute…