Quantum-Noise Reduction to improve Gravitational-Wave Detectors
Detection of gravitational waves by the Virgo detector requires exquisite control of all noise sources. In particular, a world-leading short-term frequency stability of the laser circulating in the interferometer on the mHz range is required for Virgo’s performance target [1].
The CALVA experiment at IJCLab is designed to study quantum states of light to improve Virgo’s performance. In particular, we are testing a method based on a Fabry-Perot cavity (filter cavity) for producing frequency-dependent squeezed states of light, which hold great promise for the future of gravitational-wave detectors [2]. This test requires excellent control of the laser frequency, at a level that would be compatible with Virgo’s performance. For this, we will use the ultra-stable frequency reference from the research infrastructure REFIMEVE, of which IJCLab is a member, and which is already available in the laboratory [3]. Because our laser has a different wavelength from the REFIMEVE signal (1064 nm vs. 1542 nm), an optical frequency comb is needed to transfer the stability of the ultra-stable signal to our laser.
The recent acquisition of an optical frequency comb by our team will enable a stability in the Hz range, improving our current stability by 3 orders of magnitude. This will help keep the CALVA experiment suitable for upcoming generations of gravitational-wave detectors, such as the Einstein Telescope project, not only in terms of performance, but also in terms of adaptability of the operating wavelength.
[1] F. Bondu, P. Fritschel, C. N. Man, and A. Brillet, Opt. Lett. 21, 582-584 (1996).
[2] C. M. Caves, Phys. Rev. D, 23:1693-1708 (1981).
[3] E. Cantin, M. Tønnes, R. L. Targat, A. Amy-Klein, O. Lopez, et P.-E. Pottie, New J. Phys. 23 (2021)