> "The core of the matter lays in establishing a reference point for our measurement, where light remains unaffected by Earth's rotational effect. Given our inability to halt Earth's from spinning, we devised a workaround: splitting the optical fiber into two equal-length coils and connecting them via an optical switch," explains lead author Raffaele Silvestri.
> By toggling the switch on and off, the researchers could effectively cancel the rotation signal at will, which also allowed them to extend the stability of their large apparatus. "We have basically tricked the light into thinking it's in a non-rotating universe," says Silvestri.
> By toggling the switch on and off, the researchers could effectively cancel the rotation signal at will, which also allowed them to extend the stability of their large apparatus. "We have basically tricked the light into thinking it's in a non-rotating universe," says Silvestri.
"Experimental observation of Earth's rotation with quantum entanglement" (2024) https://www.science.org/doi/10.1126/sciadv.ado0215
Sagnac interferometer: https://en.wikipedia.org/wiki/Sagnac_effect