Optimization of Quantum Noise in Space Gravitational-Wave Antenna DECIGO with Optical-Spring Quantum Locking Considering Mixture of Vacuum Fluctuations in Homodyne Detection
Kenji Tsuji,
Tomohiro Ishikawa,
Kentaro Komori,
Koji Nagano,
Yutaro Enomoto,
Yuta Michimura,
Kurumi Umemura,
Ryuma Shimizu,
Bin Wu,
Shoki Iwaguchi,
Yuki Kawasaki,
Akira Furusawa,
Seiji Kawamura
Affiliations
Kenji Tsuji
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Tomohiro Ishikawa
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Kentaro Komori
Research Center for the Early Universe (RESCEU), School of Science, University of Tokyo, Tokyo 113-0033, Tokyo, Japan
Koji Nagano
LQUOM, Inc., Tokiwadai, Hodogaya, Yokohama 240-8501, Kanagawa, Japan
Yutaro Enomoto
Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Tokyo, Japan
Yuta Michimura
Research Center for the Early Universe (RESCEU), School of Science, University of Tokyo, Tokyo 113-0033, Tokyo, Japan
Kurumi Umemura
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Ryuma Shimizu
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Bin Wu
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Shoki Iwaguchi
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Yuki Kawasaki
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Akira Furusawa
Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Tokyo, Japan
Seiji Kawamura
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Aichi, Japan
Quantum locking using optical spring and homodyne detection has been devised to reduce the quantum noise that limits the sensitivity of the DECIGO, a space-based gravitational-wave antenna in the frequency band around 0.1 Hz for the detection of primordial gravitational waves. The reduction in the upper limit of energy density ΩGW from 2×10−15 to 1×10−16, as inferred from recent observations, necessitates improved sensitivity in the DECIGO to meet its primary science goals. To accurately evaluate the effectiveness of this method, this paper considers a detection mechanism that takes into account the influence of vacuum fluctuations on homodyne detection. In addition, an advanced signal processing method is devised to efficiently utilize signals from each photodetector, and design parameters for this configuration are optimized for the quantum noise. Our results show that this method is effective in reducing quantum noise, despite the detrimental impact of vacuum fluctuations on its sensitivity.
