Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2506.02222 · Physical review. D/Physical review. D.

Performance of multiple filter-cavity schemes for frequency-dependent squeezing in gravitational-wave detectors

J. Ding, E. Capocasa, I. -L. Ahrend, Fangfei Liu, Yang Zhao, M. Barsuglia

Published Oct 28, 2025• 4 citations
arXivHTMLPDF

Abstract

Gravitational-wave detectors use state-of-the-art quantum technologies to reduce the noise induced by vacuum fluctuations, via injection of squeezed states of light. Future detectors, such as Einstein Telescope, may require the use of two filter cavities or a three-mirror coupled filter cavity to achieve a complex rotation of the squeezing ellipse, in order to reduce the quantum noise over the whole detector bandwidth. In this work, we compare the theoretical feasibility and performances of these two optical layouts and their resilience with respect to different degradation sources (optical losses, mismatching, locking precision), analytically and numerically. We extend previous analysis on squeezing degradation and find that the coupled cavity scheme provides similar or better performances than the two-cavity option, in terms of resilience with respect to imperfections and optical losses. We further highlight the role of mode-mismatch phases in limiting squeezing. Finally, we propose a possible two-step implementation scheme for Einstein Telescope using a single filter cavity that can be possibly upgraded into a coupled filter cavity.

DOI
10.1103/4s4d-9mb4

Related papers

Frequency-Dependent Squeezed Vacuum Source for Broadband Quantum Noise Reduction in Advanced Gravitational-Wave Detectors

Yang Zhao, N. Aritomi, E. Capocasa +20 more

The astrophysical reach of current and future ground-based gravitational-wave detectors is mostly limited by quantum noise, induced by vacuum fluctuations entering the detector output port. The replacement of this ordinary vacuum field with a squeezed vacuum field has proven to be an effective strategy to mitigate such quantum noise and it is currently used in advanced detectors. However, current squeezing cannot improve the noise across the whole spectrum because of the Heisenberg uncertainty principle: when shot noise at high frequencies is reduced, radiation pressure at low frequencies is increased. A broadband quantum noise reduction is possible by using a more complex squeezing source, obtained by reflecting the squeezed vacuum off a Fabry-Perot cavity, known as filter cavity. Here we report the first demonstration of a frequency-dependent squeezed vacuum source able to reduce quantum noise of advanced gravitational-wave detectors in their whole observation bandwidth. The experiment uses a suspended 300-m-long filter cavity, similar to the one planned for KAGRA, Advanced Virgo, and Advanced LIGO, and capable of inducing a rotation of the squeezing ellipse below 100 Hz.

arXiv:2003.10672•Physical Review Letters•Apr 28, 2020•104 citations

Approaches of frequency-dependent squeezing for the low frequency detector of the Einstein Telescope

Xingrui Peng, Д. В. Мартынов, Zong‐Hong Zhu +1 more

The quantum noise in gravitational-wave detectors can be suppressed in a broadband by frequency-dependent squeezing. It usually requires one large scale filter cavity and even two, for example in the low frequency detector of Einstein Telescope, which is a detuned dual recycling Fabry-Perot Michelson interferometer. In this paper, we study the feasibility of replacing two filter cavities with a coupled-cavity, aiming to reduce the optical losses with less number of optics. It turns out this approach is only theoretically valid, however, the required parameters of the optics do not support practical implementation, which is consistent with the results in Jones [Implications of the quantum noise target for the Einstein Telescope infrastructure design, ]. Furthermore, we investigate the viability of utilizing Einstein-Podolsky-Rosen (EPR) squeezing to eliminate either one or two filter cavities in the Einstein Telescope. It turns out EPR squeezing would allow us to eliminate one filter cavity, and can potentially improve the detector sensitivity with the allowance of higher input squeezing level, benefiting from the longer length of the arm cavity which serves as one of the filter cavities for frequency-dependent squeezing. Published by the American Physical Society 2024

arXiv:2404.15012•Physical review. D/Physical review. D.•Oct 15, 2024•4 citations

Frequency-Dependent Squeezing for Advanced LIGO

Lee P. McCuller, Chris Whittle, D. Ganapathy +13 more

The first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015 launched the era of gravitational-wave astronomy. The quest for gravitational-wave signals from objects that are fainter or farther away impels technological advances to realize ever more sensitive detectors. Since 2019, one advanced technique, the injection of squeezed states of light, is being used to improve the shot-noise limit to the sensitivity of the Advanced LIGO detectors, at frequencies above ∼50 Hz. Below this frequency, quantum backaction, in the form of radiation pressure induced motion of the mirrors, degrades the sensitivity. To simultaneously reduce shot noise at high frequencies and quantum radiation pressure noise at low frequencies requires a quantum noise filter cavity with low optical losses to rotate the squeezed quadrature as a function of frequency. We report on the observation of frequency-dependent squeezed quadrature rotation with rotation frequency of 30 Hz, using a 16-m-long filter cavity. A novel control scheme is developed for this frequency-dependent squeezed vacuum source, and the results presented here demonstrate that a low-loss filter cavity can achieve the squeezed quadrature rotation necessary for the next planned upgrade to Advanced LIGO, known as "A+."

arXiv:2003.13443•Physical Review Letters•Apr 28, 2020•173 citations

Decoherence and degradation of squeezed states in quantum filter cavities

P. Kwee, John Miller, Tomoki Isogai +2 more

Squeezed states of light have been successfully employed in interferometric gravitational-wave detectors to reduce quantum noise, thus becoming one of the most promising options for extending the astrophysical reach of the generation of detectors currently under construction worldwide. In these advanced instruments, quantum noise will limit sensitivity over the entire detection band. Therefore, to obtain the greatest benefit from squeezing, the injected squeezed state must be filtered using a long-storage-time optical resonator, or ``filter cavity,'' so as to realize a frequency-dependent rotation of the squeezed quadrature. While the ultimate performance of a filter cavity is determined by its storage time, several practical decoherence and degradation mechanisms limit the experimentally achievable quantum noise reduction. In this paper we develop an analytical model to explore these mechanisms in detail. As an example, we apply our results to the 16 m filter cavity design currently under consideration for the Advanced LIGO interferometers.

arXiv:1704.03531•Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields•Sep 5, 2014•92 citations

Broadband quantum noise reduction in future long baseline gravitational-wave detectors via EPR entanglement

Jacob L. Beckey, Yiqiu Ma, Vincent Boyer +1 more

Broadband quantum noise reduction can be achieved in gravitational-wave detectors by injecting frequency-dependent squeezed light into the dark port of the interferometer. This frequency-dependent squeezing can be generated by combining squeezed light with external filter cavities. However, in future long baseline interferometers (LBIs), the filter cavity required to achieve the broadband squeezing has a low bandwidth---necessitating a very long cavity to mitigate the issue from optical loss. It has been shown recently that by taking advantage of Einstein-Podolsky-Rosen (EPR) entanglement in the squeezed light source, the interferometer can simultaneously act as a detector and a filter cavity. This is an attractive broadband squeezing scheme for LBIs because the length requirement for the filter cavity is naturally satisfied by the length of the interferometer arms. In this paper we present a systematic way of finding the working points for this broadband squeezing scheme in LBIs. We also show that in LBIs, the EPR scheme achieves nearly perfect ellipse rotation as compared to 4-km interferometers which have appreciable error around the intermediate frequency. Finally, we show that an approximation for the optomechanical coupling constant in the 4-km case can break down for longer baselines. These results are applicable to future detectors such as the 10-km Einstein Telescope and the 40-km Cosmic Explorer.

arXiv:1909.03603•Physical review. D/Physical review. D.•Oct 14, 2019•7 citations

Frequency-dependent squeezing for gravitational-wave detection through quantum teleportation

Yohei Nishino, S. L. Danilishin, Yutaro Enomoto +1 more

Abstract Ground-based interferometric gravitational wave detectors are highly precise sensors for weak forces, limited in sensitivity across their detection band by quantum fluctuations of light. Current and future instruments address this limitation by injecting frequency-dependent squeezed vacuum into the detection port, utilizing narrow-band, low-loss optical cavities for optimal rotation of the squeezing ellipse at each signal frequency. This study introduces a novel scheme employing the principles of quantum teleportation and entangled states of light. It allows achieving broadband suppression of quantum noise in detuned signal recycled-Fabry-Perot--Michelson interferometers, which is the baseline design of the low-frequency detector within the Einstein Telescope xylophone detector, without requiring additional filter cavities or modifications to the core optics of the main interferometer.

arXiv:2401.04295•Physical Review A•Aug 1, 2024•13 citations
Gravitational-wave detectors use state-of-the-art quantum technologies to reduce the noise induced by vacuum fluctuations, via injection of squeezed states of light. Future detectors, such as Einstein Telescope, may require the use of two filter cavities or a three-mirror coupled filter cavity to achieve a complex rotation of the squeezing ellipse, in order to reduce the quantum noise over the whole detector bandwidth. In this work, we compare the theoretical feasibility and performances of these two optical layouts and their resilience with respect to different degradation sources (optical losses, mismatching, locking precision), analytically and numerically. We extend previous analysis on squeezing degradation and find that the coupled cavity scheme provides similar or better performances than the two-cavity option, in terms of resilience with respect to imperfections and optical losses. We further highlight the role of mode-mismatch phases in limiting squeezing. Finally, we propose a possible two-step implementation scheme for Einstein Telescope using a single filter cavity that can be possibly upgraded into a coupled filter cavity.
The astrophysical reach of current and future ground-based gravitational-wave detectors is mostly limited by quantum noise, induced by vacuum fluctuations entering the detector output port. The replacement of this ordinary vacuum field with a squeezed vacuum field has proven to be an effective strategy to mitigate such quantum noise and it is currently used in advanced detectors. However, current squeezing cannot improve the noise across the whole spectrum because of the Heisenberg uncertainty principle: when shot noise at high frequencies is reduced, radiation pressure at low frequencies is increased. A broadband quantum noise reduction is possible by using a more complex squeezing source, obtained by reflecting the squeezed vacuum off a Fabry-Perot cavity, known as filter cavity. Here we report the first demonstration of a frequency-dependent squeezed vacuum source able to reduce quantum noise of advanced gravitational-wave detectors in their whole observation bandwidth. The experiment uses a suspended 300-m-long filter cavity, similar to the one planned for KAGRA, Advanced Virgo, and Advanced LIGO, and capable of inducing a rotation of the squeezing ellipse below 100 Hz.
The quantum noise in gravitational-wave detectors can be suppressed in a broadband by frequency-dependent squeezing. It usually requires one large scale filter cavity and even two, for example in the low frequency detector of Einstein Telescope, which is a detuned dual recycling Fabry-Perot Michelson interferometer. In this paper, we study the feasibility of replacing two filter cavities with a coupled-cavity, aiming to reduce the optical losses with less number of optics. It turns out this approach is only theoretically valid, however, the required parameters of the optics do not support practical implementation, which is consistent with the results in Jones [Implications of the quantum noise target for the Einstein Telescope infrastructure design, ]. Furthermore, we investigate the viability of utilizing Einstein-Podolsky-Rosen (EPR) squeezing to eliminate either one or two filter cavities in the Einstein Telescope. It turns out EPR squeezing would allow us to eliminate one filter cavity, and can potentially improve the detector sensitivity with the allowance of higher input squeezing level, benefiting from the longer length of the arm cavity which serves as one of the filter cavities for frequency-dependent squeezing. Published by the American Physical Society 2024
The first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015 launched the era of gravitational-wave astronomy. The quest for gravitational-wave signals from objects that are fainter or farther away impels technological advances to realize ever more sensitive detectors. Since 2019, one advanced technique, the injection of squeezed states of light, is being used to improve the shot-noise limit to the sensitivity of the Advanced LIGO detectors, at frequencies above ∼50 Hz. Below this frequency, quantum backaction, in the form of radiation pressure induced motion of the mirrors, degrades the sensitivity. To simultaneously reduce shot noise at high frequencies and quantum radiation pressure noise at low frequencies requires a quantum noise filter cavity with low optical losses to rotate the squeezed quadrature as a function of frequency. We report on the observation of frequency-dependent squeezed quadrature rotation with rotation frequency of 30 Hz, using a 16-m-long filter cavity. A novel control scheme is developed for this frequency-dependent squeezed vacuum source, and the results presented here demonstrate that a low-loss filter cavity can achieve the squeezed quadrature rotation necessary for the next planned upgrade to Advanced LIGO, known as "A+."
Squeezed states of light have been successfully employed in interferometric gravitational-wave detectors to reduce quantum noise, thus becoming one of the most promising options for extending the astrophysical reach of the generation of detectors currently under construction worldwide. In these advanced instruments, quantum noise will limit sensitivity over the entire detection band. Therefore, to obtain the greatest benefit from squeezing, the injected squeezed state must be filtered using a long-storage-time optical resonator, or ``filter cavity,'' so as to realize a frequency-dependent rotation of the squeezed quadrature. While the ultimate performance of a filter cavity is determined by its storage time, several practical decoherence and degradation mechanisms limit the experimentally achievable quantum noise reduction. In this paper we develop an analytical model to explore these mechanisms in detail. As an example, we apply our results to the 16 m filter cavity design currently under consideration for the Advanced LIGO interferometers.
Broadband quantum noise reduction can be achieved in gravitational-wave detectors by injecting frequency-dependent squeezed light into the dark port of the interferometer. This frequency-dependent squeezing can be generated by combining squeezed light with external filter cavities. However, in future long baseline interferometers (LBIs), the filter cavity required to achieve the broadband squeezing has a low bandwidth---necessitating a very long cavity to mitigate the issue from optical loss. It has been shown recently that by taking advantage of Einstein-Podolsky-Rosen (EPR) entanglement in the squeezed light source, the interferometer can simultaneously act as a detector and a filter cavity. This is an attractive broadband squeezing scheme for LBIs because the length requirement for the filter cavity is naturally satisfied by the length of the interferometer arms. In this paper we present a systematic way of finding the working points for this broadband squeezing scheme in LBIs. We also show that in LBIs, the EPR scheme achieves nearly perfect ellipse rotation as compared to 4-km interferometers which have appreciable error around the intermediate frequency. Finally, we show that an approximation for the optomechanical coupling constant in the 4-km case can break down for longer baselines. These results are applicable to future detectors such as the 10-km Einstein Telescope and the 40-km Cosmic Explorer.
Abstract Ground-based interferometric gravitational wave detectors are highly precise sensors for weak forces, limited in sensitivity across their detection band by quantum fluctuations of light. Current and future instruments address this limitation by injecting frequency-dependent squeezed vacuum into the detection port, utilizing narrow-band, low-loss optical cavities for optimal rotation of the squeezing ellipse at each signal frequency. This study introduces a novel scheme employing the principles of quantum teleportation and entangled states of light. It allows achieving broadband suppression of quantum noise in detuned signal recycled-Fabry-Perot--Michelson interferometers, which is the baseline design of the low-frequency detector within the Einstein Telescope xylophone detector, without requiring additional filter cavities or modifications to the core optics of the main interferometer.