50-km fiber interferometer for testing gravitational signatures in quantum interference
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 rad root-mean-square (RMS) within the frequency range of 0.01 Hz to 5 Hz. We demonstrate that this sensitivity is sufficient to resolve a phase-shift signal of 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.
Cite
@article{arxiv.2511.17022,
title = {50-km fiber interferometer for testing gravitational signatures in quantum interference},
author = {Haocun Yu and Dorotea Macri and Thomas Morling and Eleonora Polini and Thomas B. Mieling and Peter Barrow and Begüm Kabagöz and Xinghui Yin and Piotr T. Chruściel and Christopher Hilweg and Eric Oelker and Nergis Mavalvala and Philip Walther},
journal= {arXiv preprint arXiv:2511.17022},
year = {2026}
}