- Physical Review Journals
All JournalsPhysics Magazine

Physical Review Letters

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

50-km Fiber Interferometer for Testing Gravitational Signatures in Quantum Interference

Haocun Yu1,2,*,†, Dorotea Macri3, Thomas Morling1,4,2, Eleonora Polini3,‡, Thomas B. Mieling1,2, Peter Barrow1,2, Begüm Kabagöz3, Xinghui Yin3, Piotr T. Chruściel5 et al.

Christopher Hilweg1,2, Eric Oelker3, Nergis Mavalvala3, and Philip Walther1,2,6,§

  • *Present address: Department of Physics and Astronomy, University of Tennessee, Knoxville, 1408 Circle Drive, Knoxville, Tennessee 37996, USA.
  • †Contact author: haocunyu@utk.edu
  • ‡Present address: Université Côte d’Azur, Observatoire de la Côte d’Azur, Artemis, CNRS, 06304 Nice, France.
  • §Contact author: philip.walther@univie.ac.at
PDF

Phys. Rev. Lett. 136, 110803 – Published 17 March, 2026

DOI: https://doi.org/10.1103/yvlk-t1j9

Abstract

Quantum mechanics and general relativity are the foundational pillars of modern physics, yet experimental tests that combine the two frameworks remain rare. Measuring optical phase shifts of massless photons in a gravitational potential provides a unique quantum platform to probe gravity beyond Newtonian descriptions, but laboratory-based interferometers have not yet reached the sensitivity needed to access this regime. Here, we report the realization of a 50-km table-top Mach-Zehnder fiber interferometer operating at the single-photon level, achieving a phase sensitivity of 4.42×10−6  rad  rms within the frequency range of 0.01–5 Hz. We demonstrate that this sensitivity is sufficient to resolve a phase-shift signal of 6.18(44)×10−5  rad  rms at 0.1 Hz, associated with a modulated gravity-induced signal. Our results establish a milestone for quantum sensing with large-scale optical interferometry, demonstrating the capability to detect gravitational redshifts in a local laboratory, thereby paving the way for testing quantum phenomena within general relativistic frameworks.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (61)

  1. D. Hanneke, S. Fogwell, and G. Gabrielse, New measurement of the electron magnetic moment and the fine structure constant, Phys. Rev. Lett. 100, 120801 (2008).
  2. C. M. Will, The confrontation between general relativity and experiment, Living Rev. Relativity 17, 4 (2014).
  3. LIGO Scientific and Virgo Collaborations, Observation of gravitational waves from a binary black hole merger, Phys. Rev. Lett. 116, 061102 (2016).
  4. P. Delva, N. Puchades, E. Schönemann, F. Dilssner, C. Courde, S. Bertone, F. Gonzalez, A. Hees, C. Le Poncin-Lafitte, F. Meynadier, R. Prieto-Cerdeira, B. Sohet, J. Ventura-Traveset, and P. Wolf, Gravitational redshift test using eccentric Galileo satellites, Phys. Rev. Lett. 121, 231101 (2018).
  5. M. Takamoto, I. Ushijima, N. Ohmae, T. Yahagi, K. Kokado, H. Shinkai, and H. Katori, Test of general relativity by a pair of transportable optical lattice clocks, Nat. Photonics 14, 411 (2020).
  6. T. Bothwell, C. J. Kennedy, A. Aeppli, D. Kedar, J. M. Robinson, E. Oelker, A. Staron, and J. Ye, Resolving the gravitational redshift across a millimetre-scale atomic sample, Nature (London) 602, 420 (2022).
  7. X. Zheng, J. Dolde, M. C. Cambria, H. M. Lim, and S. Kolkowitz, A lab-based test of the gravitational redshift with a miniature clock network, Nat. Commun. 14, 4886 (2023).
  8. S. Bose, A. Mazumdar, G. W. Morley, H. Ulbricht, M. Toroš, M. Paternostro, A. A. Geraci, P. F. Barker, M. S. Kim, and G. Milburn, Spin entanglement witness for quantum gravity, Phys. Rev. Lett. 119, 240401 (2017).
  9. C. Marletto and V. Vedral, Gravitationally induced entanglement between two massive particles is sufficient evidence of quantum effects in gravity, Phys. Rev. Lett. 119, 240402 (2017).
  10. M. J. W. Hall and M. Reginatto, On two recent proposals for witnessing nonclassical gravity, J. Phys. A 51, 085303 (2018).
  11. A. Kent and D. Pitalúa-García, Testing the nonclassicality of spacetime: What can we learn from Bell-Bose et al.-Marletto-Vedral experiments?, Phys. Rev. D 104, 126030 (2021).
  12. R. Colella, A. W. Overhauser, and S. A. Werner, Observation of gravitationally induced quantum interference, Phys. Rev. Lett. 34, 1472 (1975).
  13. M. Kasevich and S. Chu, Atomic interferometry using stimulated Raman transitions, Phys. Rev. Lett. 67, 181 (1991).
  14. M. Kasevich and S. Chu, Measurement of the gravitational acceleration of an atom with a light-pulse atom interferometer, Appl. Phys. B 54, 321 (1992).
  15. M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Measurement of the Earth’s gravity gradient with an atom interferometer-based gravity gradiometer, Phys. Rev. Lett. 81, 971 (1998).
  16. P. A. Altin, M. T. Johnsson, V. Negnevitsky, G. R. Dennis, R. P. Anderson, J. E. Debs, S. S. Szigeti, K. S. Hardman, S. Bennetts, G. D. McDonald, L. D. Turner, J. D. Close, and N. P. Robins, Precision atomic gravimeter based on Bragg diffraction, New J. Phys. 15, 023009 (2013).
  17. V. Xu, M. Jaffe, C. D. Panda, S. L. Kristensen, L. W. Clark, and H. Müller, Probing gravity by holding atoms for 20 seconds, Science 366, 745 (2019).
  18. C. D. Panda, M. J. Tao, M. Ceja, J. Khoury, G. M. Tino, and H. Müller, Measuring gravitational attraction with a lattice atom interferometer, Nature (London) 631, 515 (2024).
  19. C. Overstreet, P. Asenbaum, J. Curti, M. Kim, and M. A. Kasevich, Observation of a gravitational Aharonov-Bohm effect, Science 375, 226 (2022).
  20. M. Zych, F. Costa, I. Pikovski, T. C. Ralph, and Č. Brukner, General relativistic effects in quantum interference of photons, Classical Quantum Gravity 29, 224010 (2012).
  21. T. B. Mieling, T. Morling, C. Hilweg, and P. Walther, Quantum interferometry in external gravitational fields, Phys. Rev. A 112, 062211 (2025).
  22. S. Loriani, A. Friedrich, C. Ufrecht, F. Di Pumpo, S. Kleinert, S. Abend, N. Gaaloul, C. Meiners, C. Schubert, D. Tell, É. Wodey, M. Zych, W. Ertmer, A. Roura, D. Schlippert, W. P. Schleich, E. M. Rasel, and E. Giese, Interference of clocks: A quantum twin paradox, Sci. Adv. 5, eaax8966 (2019).
  23. A. Roura, Gravitational redshift in quantum-clock interferometry, Phys. Rev. X 10, 021014 (2020).
  24. A. Roura, C. Schubert, D. Schlippert, and E. M. Rasel, Measuring gravitational time dilation with delocalized quantum superpositions, Phys. Rev. D 104, 084001 (2021).
  25. P. A. Bushev, J. H. Cole, D. Sholokhov, N. Kukharchyk, and M. Zych, Single electron relativistic clock interferometer, New J. Phys. 18, 093050 (2016).
  26. J. Borregaard and I. Pikovski, Testing quantum theory on curved spacetime with quantum networks, Phys. Rev. Res. 7, 023192 (2025).
  27. J. P. Covey, I. Pikovski, and J. Borregaard, Probing curved spacetime with a distributed atomic processor clock, PRX Quantum 6, 030310 (2025).
  28. C. Fromonteil, D. V. Vasilyev, T. V. Zache, K. Hammerer, A. M. Rey, J. Ye, H. Pichler, and P. Zoller, Non-local mass superpositions and optical clock interferometry in atomic ensemble quantum networks, arXiv:2509.19501.
  29. R. Barzel, M. Gündoğan, M. Krutzik, D. Rätzel, and C. Lämmerzahl, Entanglement dynamics of photon pairs and quantum memories in the gravitational field of the earth, Quantum 8, 1273 (2024).
  30. M. Gündoğan, R. Barzel, and D. Rätzel, Gravitational time dilation in quantum clock interferometry with entangled multi-photon states and quantum memories, arXiv:2601.02470.
  31. D. Rideout, T. Jennewein, G. Amelino-Camelia, T. F. Demarie, B. L. Higgins, A. Kempf, A. Kent, R. Laflamme, X. Ma, R. B. Mann, E. Martín-Martínez, N. C. Menicucci, J. Moffat, C. Simon, R. Sorkin, L. Smolin, and D. R. Terno, Fundamental quantum optics experiments conceivable with satellites—reaching relativistic distances and velocities, Classical Quantum Gravity 29, 224011 (2012).
  32. G. Vallone, D. Dequal, M. Tomasin, F. Vedovato, M. Schiavon, V. Luceri, G. Bianco, and P. Villoresi, Interference at the single photon level along satellite-ground channels, Phys. Rev. Lett. 116, 253601 (2016).
  33. P. Xu et al., Satellite testing of a gravitationally induced quantum decoherence model, Science 366, 132 (2019).
  34. C.-Y. Lu, Y. Cao, C.-Z. Peng, and J.-W. Pan, Micius quantum experiments in space, Rev. Mod. Phys. 94, 035001 (2022).
  35. R. Barzel, D. E. Bruschi, A. W. Schell, and C. Lämmerzahl, Observer dependence of photon bunching: The influence of the relativistic redshift on Hong-Ou-Mandel interference, Phys. Rev. D 105, 105016 (2022).
  36. T. B. Mieling, C. Hilweg, and P. Walther, Measuring space-time curvature using maximally path-entangled quantum states, Phys. Rev. A 106, L031701 (2022).
  37. M. Mohageg et al., The deep space quantum link: Prospective fundamental physics experiments using long-baseline quantum optics, Eur. Phys. J. Quantum Technol. 9, 25 (2022).
  38. H.-N. Wu, Y.-H. Li, B. Li, X. You, R.-Z. Liu, J.-G. Ren, J. Yin, C.-Y. Lu, Y. Cao, C.-Z. Peng, and J.-W. Pan, Single-photon interference over 8.4 km urban atmosphere: Toward testing quantum effects in curved spacetime with photons, Phys. Rev. Lett. 133, 020201 (2024).
  39. L. Stodolsky, Matter and light wave interferometry in gravitational fields, Gen. Relativ. Gravit. 11, 391 (1979).
  40. K. Tanaka, How to detect the gravitationally induced phase shift of electromagnetic waves by optical-fiber interferometry, Phys. Rev. Lett. 51, 378 (1983).
  41. C. Hilweg, F. Massa, D. Martynov, N. Mavalvala, P. T. Chruściel, and P. Walther, Gravitationally induced phase shift on a single photon, New J. Phys. 19, 033028 (2017).
  42. S. Y. Chen and T. C. Ralph, Estimation of gravitational acceleration with quantum optical interferometers, Phys. Rev. A 99, 023803 (2019).
  43. N. Gisin, G. Ribordy, W. Tittel, and H. Zbinden, Quantum cryptography, Rev. Mod. Phys. 74, 145 (2002).
  44. P. Kok, W. J. Munro, K. Nemoto, T. C. Ralph, J. P. Dowling, and G. J. Milburn, Linear optical quantum computing with photonic qubits, Rev. Mod. Phys. 79, 135 (2007).
  45. J. L. O’Brien, A. Furusawa, and J. Vučković, Photonic quantum technologies, Nat. Photonics 3, 687–695 (2009).
  46. H. J. Kimble, The quantum internet, Nature (London) 453, 1023 (2008).
  47. S. Wehner, D. Elkouss, and R. Hanson, Quantum internet: A vision for the road ahead, Science 362, eaam9288 (2018).
  48. F. Xu, X. Ma, Q. Zhang, H.-K. Lo, and J.-W. Pan, Secure quantum key distribution with realistic devices, Rev. Mod. Phys. 92, 025002 (2020).
  49. R. Silvestri, H. Yu, T. Strömberg, C. Hilweg, R. W. Peterson, and P. Walther, Experimental observation of Earth’s rotation with quantum entanglement, Sci. Adv. 10, eado0215 (2024).
  50. C. Hilweg, D. Shadmany, P. Walther, N. Mavalvala, and V. Sudhir, Limits and prospects for long-baseline optical fiber interferometry, Optica 9, 1238 (2022).
  51. E. R. Council, GRAVITES—Gravitational interferometry with entangled states in optical fibers, ERC Grant Agreement No. 101071779 (2023).
  52. T. B. Mieling and M. Hudelist, Fiber optics in curved space-times, Phys. Rev. Res. 7, 013162 (2025).
  53. S. P. Neumann, M. Selimovic, M. Bohmann, and R. Ursin, Experimental entanglement generation for quantum key distribution beyond 1  Gbit/s, Quantum 6, 822 (2022).
  54. E. A. Ortega, J. Fuenzalida, M. Selimovic, K. Dovzhik, L. Achatz, S. Wengerowsky, R. F. Shiozaki, S. P. Neumann, M. Bohmann, and R. Ursin, Spatial and spectral characterization of photon pairs at telecommunication wavelengths from type-0 spontaneous parametric downconversion, J. Opt. Soc. Am. B 40, 165 (2023).
  55. See Supplemental Material at http://link.aps.org/supplemental/10.1103/yvlk-t1j9 for the details of the photon source, interferometer characterization, procedures for photon measurements, and an explanation of the future differential measurement scheme, which includes Ref. [56].
  56. T. B. Mieling, Gupta–Bleuler quantization of the electromagnetic field in curved space-times with applications to gravitational photon interferometry, Doctoral thesis, University of Vienna, 2023.
  57. M. Mlejnek, N. A. Kaliteevskiy, and D. A. Nolan, Reducing spontaneous Raman scattering noise in high quantum bit rate QKD systems over optical fiber, arXiv:1712.05891.
  58. H. Kawahara, A. Medhipour, and K. Inoue, Effect of spontaneous Raman scattering on quantum channel wavelength-multiplexed with classical channel, Opt. Commun. 284, 691 (2011).
  59. T. B. Mieling, On the influence of Earth’s rotation on light propagation in waveguides, Classical Quantum Gravity 37, 225001 (2020).
  60. T. B. Mieling, Gupta–Bleuler quantization of optical fibers in weak gravitational fields, Phys. Rev. A 106, 063511 (2022).
  61. H. Yu, Dataset for 50-km fiber interferometer for testing gravitational signatures in quantum interference, Zenodo, 2025, 10.5281/zenodo.17449096.

Outline

Information

Phys. Rev. Lett. 136, 110803– Published 17 March, 2026
  • Received 20 November 2025
  • Accepted 18 February 2026
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation