Abstract
Spacetime fluctuations (SFs), a common feature of proposed gravity models, could be detected using laser interferometers. To advance this effort, we provide the correspondence between expected interferometer output signals and gravity models. We consider three classes of SFs, characterised by the decay behaviours and symmetries of their two-point correlation functions. For each, we identify the low- and high-frequency behaviour of the outputs and their dependence on the interferometer’s length. Capturing these requires sensitivity over a broad frequency range that spans the light-round-trip frequency, as provided by laboratory-scale setups, whereas detecting the presence or absence of SFs can be done with high narrowband sensitivity at the light-round-trip frequency. Ou…
Abstract
Spacetime fluctuations (SFs), a common feature of proposed gravity models, could be detected using laser interferometers. To advance this effort, we provide the correspondence between expected interferometer output signals and gravity models. We consider three classes of SFs, characterised by the decay behaviours and symmetries of their two-point correlation functions. For each, we identify the low- and high-frequency behaviour of the outputs and their dependence on the interferometer’s length. Capturing these requires sensitivity over a broad frequency range that spans the light-round-trip frequency, as provided by laboratory-scale setups, whereas detecting the presence or absence of SFs can be done with high narrowband sensitivity at the light-round-trip frequency. Our approach applies to interferometers with arm cavities, such as the km-long LIGO detectors, and those without, like laboratory-scale setups QUEST and GQuEST. Finally, we constrain the strength and correlation scale of SFs by comparing our modelled signals with experimental data.
Data availability
The datasets from QUEST and the Holometer were analysed during the current study. The Holometer dataset belongs to Fermilab and is shared publicly as mentioned in https://holometer.fnal.gov/. A limited access to the QUEST dataset was provided to the authors by Prof Hartmut Grote from the University of Cardiff, for the sole purpose of analysis. Therefore, this dataset cannot be shared publicly by the authors of this manuscript.
Code availability
We do not use custom code or mathematical algorithms that are central to the conclusions of this work.
References
Rovelli, C.Notes for a brief history of quantum gravity, 742–768 https://www.worldscientific.com/doi/abs/10.1142/9789812777386_0059 (World Scientific, Singapore, 2002). 1.
Bassi, A., Großardt, A. & Ulbricht, H. Gravitational decoherence. Class. Quant. Grav. 34, 193002 (2017).
Wheeler, J. A. On the nature of quantum geometrodynamics. Ann. Phys. (NY) 2, 604–614 (1957).
Carlip, S. Spacetime foam: a review. Rep. Prog. Phys. 86, 066001 (2023).
Rosenfeld, L. On quantization of fields. Nucl. Phys. 40, 353–356 (1963).
Ruffini, R. & Bonazzola, S. Systems of self-gravitating particles in general relativity and the concept of an equation of state. Phys. Rev. 187, 1767–1783 (1969).
van Meter, J. R. Schrödinger-newton ‘collapse’ of the wavefunction. Class. Quant. Grav. 28, 215013 (2011).
Kafri, D., Taylor, J. M. & Milburn, G. J. A classical channel model for gravitational decoherence. New J. Phys. 16, 065020 (2014).
Tilloy, A. & Diósi, L. Sourcing semiclassical gravity from spontaneously localized quantum matter. Phys. Rev. D 93, 024026 (2016).
Oppenheim, J., Sparaciari, C., Šoda, B. & Weller-Davies, Z. Gravitationally induced decoherence vs space-time diffusion: testing the quantum nature of gravity. Nat. Commun. 14, 7910 (2023).
Pelliconi, P., Sonner, J. & Verlinde, H. Gravity as a mesoscopic system. J. High Energ. Phys. 2025, 97 (2025). 1.
Allen, B. & Romano, J. D. Detecting a stochastic background of gravitational radiation: signal processing strategies and sensitivities. Phys. Rev. D 59, 102001 (1999).
Servant, G. & Simakachorn, P. Ultrahigh frequency primordial gravitational waves beyond the kHz: the case of cosmic strings. Phys. Rev. D 109, 103538 (2024).
Oppenheim, J. A postquantum theory of classical gravity? Phys. Rev. X 13, 041040 (2023).
Van Raamsdonk, M. Building up space-time with quantum entanglement. Int. J. Mod. Phys. D 19, 2429–2435 (2010).
Li, D., Lee, V. S. H., Chen, Y. & Zurek, K. M. Interferometer response to geontropic fluctuations. Phys. Rev. D 107, 024002 (2023).
Carney, D., Karydas, M. & Sivaramakrishnan, A. Response of interferometers to the vacuum of quantum gravity. Preprint at arXiv https://doi.org/10.48550/arXiv.2409.03894 (2024). 1.
Verlinde, E. P. & Zurek, K. M. Observational signatures of quantum gravity in interferometers. Phys. Lett. B 822, 136663 (2021).
Kwon, O. Phenomenology of holography via quantum coherence on causal horizons. Found. Phys. 55, 19 (2025).
Vasileiou, V., Granot, J., Piran, T. & Amelino-Camelia, G. A Planck-scale limit on spacetime fuzziness and stochastic Lorentz invariance violation. Nat. Phys. 11, 344–346 (2015).
Oniga, T. & Wang, C. H.-T. Quantum gravitational decoherence of light and matter. Phys. Rev. D 93, 044027 (2016).
Lee, V. S. H., Zurek, K. M. & Chen, Y. Astronomical image blurring from transversely correlated quantum gravity fluctuations. Phys. Rev. D 109, 084005 (2024).
Amelino-Camelia, G. Gravity-wave interferometers as quantum-gravity detectors. Nature 398, 216–218 (1999).
Sharmila, B., Vermeulen, S. M. & Datta, A. Extracting electromagnetic signatures of spacetime fluctuations. Class. Quant. Grav. 41, 075003 (2024).
Vermeulen, S. M. et al. Photon-counting interferometry to detect geontropic space-time fluctuations with GQuEST. Phys. Rev. X 15, 011034 (2025).
Grote, H. & the LIGO Scientific Collaboration. The GEO 600 status. Class. Quant. Grav. 27, 084003 (2010).
Hogan, C. J. Measurement of quantum fluctuations in geometry. Phys. Rev. D 77, 104031 (2008).
Chou, A. et al. Interferometric constraints on quantum geometrical shear noise correlations. Class. Quant. Grav. 34, 165005 (2017).
Vermeulen, S. M. et al. An experiment for observing quantum gravity phenomena using twin table-top 3d interferometers. Class. Quant. Grav. 38, 085008 (2021).
Ruo Berchera, I., Degiovanni, I. P., Olivares, S. & Genovese, M. Quantum light in coupled interferometers for quantum gravity tests. Phys. Rev. Lett. 110, 213601 (2013).
Ruo-Berchera, I. et al. One- and two-mode squeezed light in correlated interferometry. Phys. Rev. A 92, 053821 (2015).
Gardner, J. W. et al. Stochastic waveform estimation at the fundamental quantum limit. PRX Quantum 6, 030311 (2025).
Ashcroft, N. W. & Mermin, N. D. Solid state physics https://archive.org/details/AshcroftSolidState/mode/2up (Saunders College Publishing, USA, 1976). 1.
Balakrishnan, V. Elements of Nonequilibrium Statistical Mechanics. https://doi.org/10.1007/978-3-030-62233-6 (Springer, Cham, 2020). 1.
Karolyhazy, F. Gravitation and quantum mechanics of macroscopic objects. Nuovo Cimento A (1965–1970) 42, 390–402 (1966).
Figurato, L., Bassi, A. & Donadi, S. On the testability of the Károlyházy model. New J. Phys. 26, 013001 (2024).
Ghirardi, G. C., Rimini, A. & Weber, T. Unified dynamics for microscopic and macroscopic systems. Phys. Rev. D 34, 470–491 (1986).
Ghirardi, G. C., Pearle, P. & Rimini, A. Markov processes in Hilbert space and continuous spontaneous localization of systems of identical particles. Phys. Rev. A 42, 78–89 (1990).
Diósi, L. Gravitation and quantum-mechanical localization of macro-objects. Phys. Lett. A 105, 199–202 (1984).
Diósi, L. Models for universal reduction of macroscopic quantum fluctuations. Phys. Rev. A 40, 1165–1174 (1989).
Penrose, R. On gravity’s role in quantum state reduction. Gen. Relat. Gravit. 28, 581–600 (1996).
GWTC-3: Compact binary coalescences observed by LIGO and Virgo during the second part of the third observing run – data behind the figures. https://doi.org/10.5281/zenodo.5571766 (LIGO Scientific Collaboration, Virgo Collaboration, and KAGRA Collaboration, 2022). 1.
Kwon, O. & Hogan, C. J. Interferometric tests of planckian quantum geometry models. Class. Quant. Grav. 33, 105004 (2016).
Chou, A. et al. The Holometer: an instrument to probe Planckian quantum geometry. Class. Quant. Grav. 34, 065005 (2017).
Patra, A. et al. Broadband limits on stochastic length fluctuations from a pair of table-top interferometers. Phys. Rev. Lett. 135, 101402 (2025).
Martynov, D. V. et al. Quantum correlation measurements in interferometric gravitational-wave detectors. Phys. Rev. A 95, 043831 (2017).
Lee, V. S. H. & Zurek, K. M. Proper time observables of general gravitational perturbations in laser interferometry-based gravitational wave detectors. Phys. Rev. D 111, 124037 (2025).
Whitcomb, S. E. Optical pathlength fluctuations in an interferometer due to residual gas. Tech. Rep. https://authors.library.caltech.edu/records/m4bsr-0mg82 (1984). 1.
Weiss, R. LIGO-T2200336-v2: Considerations of a LIGO in air. Tech. Rep. https://dcc.ligo.org/LIGO-T2200336. LIGO Technical Note LIGO-T2200336-v2 (2022). 1.
Grado, A. et al. Ultra high vacuum beam pipe of the Einstein Telescope Project: challenges and perspectives. J. Vac. Sci. Technol. B 41, 024201 (2023).
Tsagas, C. G. Electromagnetic fields in curved spacetimes. Class. Quant. Grav. 22, 393 (2004).
Padmanabhan, T. Gravitation: Foundations and Frontiers, 221–224 (Cambridge University Press, 2010). https://doi.org/10.1017/CBO9780511807787. 1.
Romano, J. D. & Cornish, N. J. Detection methods for stochastic gravitational-wave backgrounds: a unified treatment. Living Rev. Relativ. 20, 2 (2017).
Acknowledgements
We thank Hartmut Grote, Jonathan Oppenheim and Ohkyung Kwon for extensive discussions and suggestions crucial to this work. We also thank Vincent Lee for clarifications on the Pixellon model. We thank the QUEST team for sharing data for comparison with our results. BS thanks Dr. V. Balakrishnan for vital clarifications and discussions on aspects of stationarity. BS and AD acknowledge the UK STFC “Quantum Technologies for Fundamental Physics” programme (Grant Numbers ST/T006404/1, ST/W006308/1 and ST/Y004493/1) for support. BS also acknowledges the support of the Leverhulme Trust under research grant ECF-2024-124. SMV acknowledges the support of the Leverhulme Trust under research grant RPG-2019-022.
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Authors and Affiliations
Department of Physics, University of Warwick, Coventry, UK
B. Sharmila & Animesh Datta 1.
Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, USA
Sander M. Vermeulen
Authors
- B. Sharmila
- Sander M. Vermeulen
- Animesh Datta
Contributions
B.S. contributed to methodology, formal analysis, data curation, visualisation, writing—original draft and editing. S.M.V. contributed to conceptualisation, methodology, formal analysis, writing—review and editing. A.D. contributed to conceptualisation, methodology, formal analysis, writing—review and editing, supervision and project administration.
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Correspondence to B. Sharmila.
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Sharmila, B., Vermeulen, S.M. & Datta, A. Signatures of correlation of spacetime fluctuations in laser interferometers. Nat Commun (2025). https://doi.org/10.1038/s41467-025-67313-3
Received: 10 July 2025
Accepted: 26 November 2025
Published: 23 December 2025
DOI: https://doi.org/10.1038/s41467-025-67313-3