The Quantum Entanglement Experiment that Defied Earth’s Rotation
In a groundbreaking experiment led by Philip Walther at the University of Vienna, researchers have successfully measured the effect of Earth’s rotation on quantum entangled photons. Published in Science Advances, this work represents a leap in rotation sensitivity in entanglement-based sensors, hinting at exciting possibilities at the juncture of quantum mechanics and general relativity.
Traditional optical Sagnac interferometers have long been the go-to for measuring rotations, setting the stage for Einstein’s special theory of relativity. These devices are incredibly precise but are limited by the laws of classical physics. Quantum entanglement, on the other hand, offers a chance to break through these boundaries by providing more information than conventional measurements.
The Viennese team’s experiment involved the construction of a massive optical fiber Sagnac interferometer, where they managed to keep noise levels low and stable for extended periods. This allowed them to detect high-quality entangled photon pairs, surpassing the rotation precision of previous quantum optical Sagnac interferometers by a thousandfold.
In a traditional Sagnac interferometer, particles travel in opposite directions around a closed path, arriving at the starting point at different times. Entangled particles, however, behave like a single entity, testing both directions simultaneously and accumulating a time delay twice that of non-entangled particles. This phenomenon, known as super-resolution, was demonstrated in their 2-kilometer-long optical fiber setup.
One of the key challenges the researchers faced was isolating Earth’s rotation signal from their measurements. By utilizing a clever optical switch to cancel out the rotational effect, they were able to extend the stability of their experiment. “We have essentially created a scenario where light perceives itself in a non-rotating universe,” explains lead author Raffaele Silvestri.
The successful observation of Earth’s rotation on a maximally entangled two-photon state confirms the intricate relationship between rotating reference frames and quantum entanglement, as predicted by Einstein’s special theory of relativity and quantum mechanics. This achievement marks a significant milestone in the field, with the potential to revolutionize the sensitivity of entanglement-based sensors in the future.
As we look towards the horizon of quantum entanglement and spacetime, Philip Walther believes that this experiment will pave the way for further advancements in rotation sensitivity and open up new avenues for exploring the behavior of quantum entanglement in relation to the curves of spacetime.