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Your search keyword '"Ryuichi Ichikawa"' showing total 5 results
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5 results on '"Ryuichi Ichikawa"'

1. Geodetic measurements and quantitative evaluation for reduced gravitational redshift uncertainty of NICT optical frequency standards

Author

Ryuichi, Ichikawa, primary, Hidekazu, Hachisu, additional, Mamoru, Sekido, additional, Tetsuya, Ido, additional, Yoshifumi, Hiraoka, additional, Eiichirou, Harima, additional, Shuntaro, Fukaya, additional, Koji, Matsuo, additional, Masahiro, Nakashima, additional, Yuichi, Aoyama, additional, Akihisa, Hattori, additional, and Yoichi, Fukuda, additional

Published
2023
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2. Intercontinental Comparison of Lattice Clocks Using a Broadband VLBI Technique

Author

Filippo Levi, Claudio Bortolotti, Ryuichi Ichikawa, Marco Pizzocaro, Mamoru Sekido, Federico Perini, G. Cerretto, M. Tsusumi, Filippo Bregolin, Eiji Kawai, Giuseppe Maccaferri, Tetsuya Ido, Davide Calonico, H. Ishijima, Hideki Ujihara, Monia Negusini, Nils Nemitz, Alberto Mura, Roberto Ricci, H. Hachisu, K. Takefuji, Piero Barbieri, Cecilia Clivati, Mauro Roma, ITA, and JPN

Subjects
Physics, Optical fiber, 010504 meteorology & atmospheric sciences, Clock signal, business.industry, 01 natural sciences, Frequency difference, law.invention, Radio observatory, Optics, law, Lattice (order), 0103 physical sciences, Broadband, Very-long-baseline interferometry, Optical clock, business, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

We performed a frequency comparison of lattice clocks in Tokyo and Torino for the first time using broadband VLBI technique. Two portable antennas with 2.4 m diameters were installed at NICT Koganei headquarters and INAF Medicina Radio Observatory, close to Bologna, Italy, realizing a VLBI network together with Kashima large-aperture antenna of 34 m diameter. The clock signal at INAF was evaluated by INRIM using an optical fiber link between Medicina and Torino. The fractional frequency difference that VLBI evaluated was consistent with the difference between two HM frequencies which were separately calibrated by a Sr lattice clock at NICT and a Yb lattice clock at INRIM.

Published
2019

3. Adaptive sampling, terahertz dual comb spectroscopy using unstabilized dual lasers

Author

Yi-Da Hsieh, Takeshi Yasui, Tatsuya Mizuguchi, Kaoru Minoshima, Takuma Matsumoto, Hajime Inaba, and Ryuichi Ichikawa

Subjects
Materials science, Optical fiber, business.industry, Terahertz radiation, Laser, Terahertz spectroscopy and technology, law.invention, Optics, law, Fiber laser, Femtosecond, Optoelectronics, Radio frequency, Spectroscopy, business
Abstract

Terahertz (THz) dual comb spectroscopy (DCS) is a promising method for high-accuracy, high-resolution, broadband THz spectroscopy. In this paper, we have demonstrated adaptive-sampling THz-DCS, allowing the use of unstabilized dual femtosecond lasers.

Published
2015
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5. Precise frequency transfer experiments using VLBI and other techniques

Author

Ryuichi, Ichikawa, primary, Hiroshi, Takiguchi, additional, Moritaka, Kimura, additional, Atsutoshi, Ishii, additional, Thomas, Hobiger, additional, Yasuhiro, Koyama, additional, Tetsuro, Kondo, additional, Yasuhiro, Takahashi, additional, Shigeru, Tsuchiya, additional, Fumimaru, Nakagawa, additional, Maho, Nakamura, additional, Ryo, Tabuchi, additional, Shinichi, Hama, additional, Tadahiro, Gotoh, additional, Miho, Fujieda, additional, Masanori, Aida, additional, Tingyu, Li, additional, and Jun, Amagai, additional

Published
2011
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