重力波検出器ＫＡＧＲＡの感度向上のための周波数依存スクイージング技術の開発

2019 年度 実績報告書

• 研究課題/領域番号: 18F18024
• 研究機関: 国立天文台
• 研究代表者: フラミニオ ラファエレ 国立天文台, 重力波プロジェクト, 特任教授 (10723108)
• 研究分担者: CAPOCASA ELEONORA 国立天文台, 重力波プロジェクト, 外国人特別研究員
• 研究期間 (年度): 2018-10-12 – 2021-03-31
• キーワード: gravitational waves / squeezing

研究実績の概要

The activity of the past FY was firstly focused on the improvement of the two main components of the experiment (the frequency independent squeezing source and the filter cavity) and later to the coupling of the squeezing into the cavity to produce frequency dependent squeezing.
Thanks to an intense noise hunting activity, the performances of the frequency independent squeezing source have been improved and it is now able to produce 6dB of squeezing starting from 10 Hz. A set of custom analog servos for the control of different loops of the setup has been realized and deployed. Thank to this system we are now able to bring the setup on its working state in few seconds.
For what concerned the suspended filter cavity, we completed the transition to the new KAGRA-style digital control system and we implemented an automatic alignment technique using a signal generated by dithering the angular position of the cavity mirrors.
After that we worked on the coupling of the squeezed beam into the cavity and in January we were finally able to obtain the first measurement of frequency dependent squeezing, with rotation angle below 100 Hz. We measured a squeezing level of ~3.5 dB above the rotation frequency and a squeezing level of at least 1 dB at the rotation frequency and below.
The paper reporting these results has been accepted by Phys. Rev. Lett. on 23rd March 2020.

現在までの達成度 (区分)

1: 当初の計画以上に進展している

理由

This year the results obtained by Eleonora were excellent. Thanks to her valuable conribution we were able to realize the first measurement of frequency dependent squeezing in the frequency band of interest for gravitational wave detectors. This results has been published on Phisical Review Letters and it was hilighted on Physics APS, Physics and Photonics News and Nature.

今後の研究の推進方策

This future activity will be mainly dedicated on the improvement of the system performances through two main actions:
1) Reduction of optical losses in the system by the replacing some critical optical components of the setup (OPO, Faraday Isolator, etc.).
2) Improvement of filter cavity stability by implementing an automatic alignment system where the error signals for the control are provided by quadrant photodiodes.
We also plan to test an alternative control technique for the filter cavity, that we have been studying recently.
We will continue to work on the design for a filter cavity to be implemented in a future upgrade of KAGRA.

研究成果

• [国際共同研究] CNRS/APC/CNRS/LAPP(フランス)
  • 国名: フランス
  • 外国機関名: CNRS/APC/CNRS/LAPP
• [国際共同研究] NIKHEF(オランダ)
  • 国名: オランダ
  • 外国機関名: NIKHEF
• [国際共同研究] National Tsing Hua University(中国)
  • 国名: 中国
  • 外国機関名: National Tsing Hua University
• [雑誌論文] First cryogenic test operation of underground km-scale gravitational-wave observatory KAGRA (2019)
  • 著者名/発表者名: T Akutsu, M Ando, K Arai, Y Arai, S Araki, A Araya, N Aritomi, H Asada, Y Aso, S Atsuta, K Awai, S Bae, L Baiotti, M A Barton, K Cannon, E Capocasa, C-S Chen, T-W Chiu, K Cho, Y-K Chu, K Craig, W Creus, K Doi, K Eda, Y Enomoto, R Flaminio, et al.
  • 雑誌名: Classical and Quantum Gravity 巻: 36 ページ: 165008
  • DOI: 10.1088/1361-6382/ab28a9
  • 査読あり / 国際共著
• [雑誌論文] Vibration isolation system with a compact damping system for power recycling mirrors of KAGRA (2019)
  • 著者名/発表者名: Y Akiyama, T Akutsu, M Ando, K Arai, Y Arai, S Araki, A Araya, N Aritomi, H Asada, Y Aso, S Bae, L Baiotti, M A Barton, K Cannon, E Capocasa, C-S Chen, T-W Chiu, K Cho, Y-K Chu, K Craig, V Dattilo, K Doi, Y Enomoto, R Flaminio, et al.
  • 雑誌名: Classical and Quantum Gravity 巻: 36 ページ: 095015
  • DOI: 10.1088/1361-6382/ab0fcb
  • 査読あり / 国際共著
• [学会発表] Enhancing the sensitivity of gravitational wave detectors using squeezed vacuum states of light (2019)
  • 著者名/発表者名: Eleonora Capocasa
  • 学会等名: Seminar at LAPP, Annecy, France
  • 招待講演
• [学会発表] Quantum noise in interferometric gravitational wave detectors (2019)
  • 著者名/発表者名: Eleonora Capocasa
  • 学会等名: Seminar at the Wuhan University, China
  • 招待講演
• [学会発表] Status of the frequency dependent squeezing experiment at TAMA (2019)
  • 著者名/発表者名: Eleonora Capocasa
  • 学会等名: GWDAW 2019, Isola d'Elba, Italy