| 研究課題/領域番号 |
21H04476
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| 研究機関 | 国立天文台 |
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研究代表者 |
LEONARDI MATTEO 国立天文台, 重力波プロジェクト, 特別客員研究員 (90816448)
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| 研究分担者 |
麻生 洋一 国立天文台, 重力波プロジェクト, 准教授 (10568174)
Zhao Yuhang 東京大学, 宇宙線研究所, 特任研究員 (70897834)
道村 唯太 東京大学, 大学院理学系研究科(理学部), 客員共同研究員 (80747006)
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| 研究期間 (年度) |
2021-04-05 – 2024-03-31
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| キーワード | quantum noise / gravitational wave / KAGRA / filter cavity / freq. dep. squeezing |
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| 研究実績の概要 |
In FY2021 and FY2022 a lot of work has been devoted to improve the stability of the filter cavity. The first approach which was tested was the use of a so called bichromatic control scheme which aims to control the length, alignment and incident beam pointing degrees of freedom via a second harmonic beam produced from a field at the same frequency of the squeezed field. The study lasted for the majority of FY2021 and was successfully concluded in FY2022. A paper on Physical Review D was published on it. With this control, a factor of 6 improvement on the filter cavity detuning was achieved, bringing this parameter within the requirement for implementation in KAGRA. The second approach tested in FY2022 was proposed earlier by our group with a theoretical study. In this scheme the coherent control sidebands are used to provide the error signal for the filter cavity length. Such scheme was experimentally demonstrated and proved to improve the lock of the filter cavity with respect to the results obtained in the PRL of 2020 published by the group. The results of this demonstration have also been published in Physical Review D.
Finally, mainly in FY2022, several steps have been performed to reduce the impact of optical losses. In particular, the new low losses Faraday isolator has been characterized and the new low loss Optical Parametric Oscillator has been realized and characterized. The new low losses component will allow for a better characterization of scattering losses which will in turn lead to better understanding the role of polishing specs in the filter cavity system.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
The aging of TAMA electronics requested a small adjustment of schedule to refurbish the failing parts. Unfortunately, mainly due to the
difficulties in procurement of components due to the ending of the Covid pandemic as well as the rampaging Russo-Ukrainian war, created some
delays.
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| 今後の研究の推進方策 |
The activity in FY2023 will start by finalizing the scattering light characterization and installation of new low losses components (in-vacuum FI and OPO). This activities will give insight in the source of phase noise and finally define the requirements for substrates and coatings. This items will be procured after this finalization. In parallel the design of new generation suspension will be done and the fabrication of such suspensions will be performed. The characterization of the first prototype of the new suspension is planned in the second half of FY2023. Finally, due to the aging of current control electronics, several components are planned to be replaced or improved along the course of the year.
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