First-step experiment in developing optical-spring quantum locking for DECIGO: sensitivity optimization for simulated quantum noise by completing the square
General Relativity and Quantum Cosmology2023-02-01v1Quantum Physics
DECi-hertz Interferometer Gravitational Wave Observatory (DECIGO) is a future mission for a space-borne laser interferometer. DECIGO has 1,000-km-long arm cavities mainly to detect the primordial gravitational waves (PGW) at lower frequencies around 0.1 Hz. Observations in the electromagnetic spectrum have lowered the bounds on the upper limit of PGW energy density (Ωgw∼10−15→10−16). As a result, DECIGO's target sensitivity, which is mainly limited by quantum noise, needs further improvement. To maximize the feasibility of detection while constrained by DECIGO's large diffraction loss, a quantum locking technique with an optical spring was theoretically proposed to improve the signal-to-noise ratio of the PGW. In this paper, we experimentally verify one key element of the optical-spring quantum locking: sensitivity optimization by completing the square of multiple detector outputs. This experiment is operated on a simplified tabletop optical setup with classical noise simulating quantum noise. We succeed in getting the best of the sensitivities with two different laser powers by the square completion method.
@article{arxiv.2211.12683,
title = {First-step experiment in developing optical-spring quantum locking for DECIGO: sensitivity optimization for simulated quantum noise by completing the square},
author = {Tomohiro Ishikawa and Yuki Kawasaki and Kenji Tsuji and Rika Yamada and Izumi Watanabe and Bin Wu and Shoki Iwaguchi and Ryuma Shimizu and Kurumi Umemura and Koji Nagano and Yutaro Enomoto and Kentaro Komori and Yuta Michimura and Akira Furusawa and Seiji Kawamura},
journal= {arXiv preprint arXiv:2211.12683},
year = {2023}
}