2019 Fiscal Year Annual Research Report
Broadband quantum noise reduction via EPR squeezing
| Project/Area Number |
18H01235
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
LEONARDI MATTEO 国立天文台, 重力波プロジェクト, 助教 (90816448)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | quantum optics / gravitational wave / frequency dep. squeezing / filter cavity / KAGRA |
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| Outline of Annual Research Achievements |
In FY2019 a major achievement was obtained: the first measurement of frequency dependent squeezing. This result is crucial, not only because it was the first time in the world that a frequency dependent squeezing was measured with rotation below 100Hz, but also since this technology is meant to be implemented in current GW detector and our experiment is a full scale prototype which will give valuable information to the GW community. The relevance of this result is highlighted by the fact that it was published on PRL and was among the editor suggested and highlighted topics.
This achievement was obtained in three steps: the first is the improvement of the frequency independent squeezed source. The first FIS was obtained in FY2018 and after that, a large amount of time was allocated to characterize such FIS and understand the main limitation and degradation processes. All these problems were addressed and we can produce now about 6dB of FIS down to 10Hz. The second step is the implementation of the digital system (DGS). In FY2018 we had the failure of the old TAMA DGS and we started replacing it with a KAGRA compatible one. Thanks to the help from KAGRA people, we could install and operate the new DGS and now most of the experiment can be operated remotely. The third and last step was the optimization of the injection of FIS into the filter cavity and the detection with homodyne detector. This step took several months of alignment since, due to the lack of an automatic alignment system, the optimal alignment condition drifts on minute basis.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
With the successful measurement of frequency dependent squeezing, the project is entering the final phase. At this stage most of the components have been installed (the only missing are the second homodyne detector and a working automatic alignment system) and commissioned. There are still several individual component that, even if their performances are acceptable, could perform better. The possibility of such improvements will be analyzed and eventually addressed.
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| Strategy for Future Research Activity |
After the achievement of FY2019, several improvements point were identified. The main one is the installation of an automatic alignment system for the filter cavity. This will allow for longer operational time of the experiment, allowing for better characterization of the FC itself as well as many other part of the system. Another improvement point we want to address are the Faraday isolator optical losses as well as the FC residual length noise. To address the latter one, a novel locking scheme is envisaged. The final step will be the installation of the second homodyne detector (which is an identical copy of the current one, therefore no problem in operating it is expected) and the measurement of EPR squeezing.
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