A group of researchers led by Philip Walther from the University of Vienna conducted a unique experiment in which the effect of the Earth’s rotation was measured on quantum entangled photons. The classical tool for proving the accuracy of the general theory of relativity was first used to evaluate the phenomenon of quantum mechanics, which paved the way for finding a connection between the material and quantum worlds.

The research study was published in the journal Science Developments. Scientists have created the world’s largest Sagnac interferometer known for nearly a century. This device or sensor makes it possible to find evidence for a number of propositions of the theory of general relativity, in particular, for example, the most sensitive spin detector of our planet. The Viennese researchers mounted their version of the device on a 1.4 aluminum frame (spool) and wound two coils of optical cables of 2 km each.

The winding insulation was reliable enough to reduce the quantum noise level below the specified sensitivity limit for several hours. This made it possible to safely detect a sufficient number of entangled photons to later use for the experiment.

Scientists explained that a spiral does not allow establishing a reference point for measurements, that is, extracting a signal of the constant rotation of the Earth from the measurement data. It had to be “Tricking light into thinking the universe is stable.” This effect was achieved by switching between windings.

“The crux of the problem is – lead author Raffaele Silvestri explains: – It was to create a reference point for our measurements where the light was not affected by the effect of the Earth’s rotation. “Given that we cannot stop the Earth’s rotation, we came up with a solution: We split the optical fiber into two coils of equal length and connected them with an optical switch.” Using a switch, the researchers were able to effectively suppress the rotation signal, allowing them to increase the stability of the device. “We actually tricked the light into thinking it was in a universe that wasn’t rotating.” Silvestri said.

The idea behind the experiment is that entangled photons give more information when measured than normal photons. This could help push the boundaries of the device’s sensitivity beyond classical physics into the realm of quantum mechanics.

In a conventional Sagnac interferometer, two photons will move towards each other and return to the starting point with some time difference depending on the rotation speed of the system. In the case of entangled photons the situation is more complex; both photons move towards each other simultaneously as a single particle. Scientists explain that the time delay also doubles, which doubles the resolution of the sensor, meaning what is called super resolution is achieved.

This confirmed the interaction between rotating reference frames and quantum entanglement; The theoretical explanation for this can be found in both Einstein’s special theory of relativity and quantum mechanics. This was done with a thousandfold increase in accuracy compared to previous experiments.

“This is an important milestone because, a century after the light-assisted rotation of the Earth was first observed, the entanglement of individual light quanta has finally entered the same mode of precision. – explained Haocun Yu, who worked on this experiment as a researcher at the institute. Marie Curie. — I believe that our results and methodology will form the basis for further improvements in the sensitivity of sensors based on entanglement rotation estimation. “This could pave the way for future experiments to test the curvature of space-time and the behavior of quantum entanglement.”