Probing general relativity-induced decoherence using an on-chip Sagnac interferometer

The intersection of quantum mechanics and general relativity remains an open frontier in fundamental physics, with few experimentally accessible phenomena connecting the two. Recent theoretical proposals suggest that relativistic proper time can act as a source of decoherence in quantum systems, providing a testable overlap between the two theories. Here, we propose a chip-integrated Sagnac interferometer where rotation induces a proper time difference between clockwise and counterclockwise single-photon paths. When this time delay exceeds the photon's coherence time, interference visibility is predicted to decrease, offering a direct signature of relativistic time dilation-induced decoherence. We theoretically derive the proper time difference arising from the Sagnac effect and estimate that for a loop radius of 18.9 cm and a rotation speed of 1000 rad/s, decoherence should occur for single-photon wavepackets with a coherence time of 10 femtoseconds. We also present a practical chip design that accommodates the required high-speed mechanical rotation and includes an all-optical readout scheme to eliminate wiring constraints. This approach enables a stable, on-chip implementation using realistic parameters, with rotation speed serving as a continuously tunable knob to control decoherence. Our platform opens a new route for experimentally probing the interplay between quantum coherence and relativistic proper time in a scalable and compact form.