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arXiv · 2610.18131

Spectrally enhanced gravitational redshift signals in photonic interferometry

Jerzy Paczos·Piotr T. Grochowski·Natalia Bruno·Emanuele Distante·Stephan Welte·Magdalena Zych
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Abstract

Quantum mechanics and general relativity are remarkably successful, yet their joint predictions remain beyond direct experimental reach. Photonic interferometers operating in a gravitational field offer a promising route to test this regime: gravitational redshift differentiates photon propagation between vertically separated arms, leading to a predicted phase shift and reduction in interference visibility. These effects are minute on laboratory scales, motivating existing proposals to consider large interferometer areas to accumulate them geometrically. Indeed, such schemes typically require kilometre-scale optical paths to produce appreciable interferometric signals. Here, we propose a strategy that replaces geometric accumulation with spectral enhancement by coupling the two interferometer arms to optical scatterers based on ultranarrow atomic transitions. These transitions serve as local spectral references: gravitational redshift changes the photon's detuning from each resonance, producing large differences in reflection amplitude and hence substantial visibility loss and interferometric phase shift already for centimetre-scale height differences. We quantify the experimental requirements and assess the feasibility of implementation with current or near-term technology. Our proposal thus opens a route to tabletop optical tests of the interplay between quantum mechanics and general relativity.

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Jerzy Paczos, Piotr T. Grochowski, Natalia Bruno, Emanuele Distante, Stephan Welte, Magdalena Zych. 2026-10-13. Spectrally enhanced gravitational redshift signals in photonic interferometry. https://arxiv.org/abs/2610.18131

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