2019 Fiscal Year Annual Research Report
Development of frequency dependent squeezing technique for sensitivity improvement of gravitational wave detector KAGRA
| Project/Area Number |
18F18024
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
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)
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| Co-Investigator(Kenkyū-buntansha) |
CAPOCASA ELEONORA 国立天文台, 重力波プロジェクト, 外国人特別研究員
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| Project Period (FY) |
2018-10-12 – 2021-03-31
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| Keywords | gravitational waves / squeezing |
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| Outline of Annual Research Achievements |
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.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
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.
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| Strategy for Future Research Activity |
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.
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[Journal Article] First cryogenic test operation of underground km-scale gravitational-wave observatory KAGRA2019
Author(s)
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.
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Journal Title
Classical and Quantum Gravity
Volume: 36
Pages: 165008
DOI
Peer Reviewed / Int'l Joint Research
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[Journal Article] Vibration isolation system with a compact damping system for power recycling mirrors of KAGRA2019
Author(s)
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.
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Journal Title
Classical and Quantum Gravity
Volume: 36
Pages: 095015
DOI
Peer Reviewed / Int'l Joint Research
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