A Quantum Leap in Measuring Earth’s Rotation
For over a century, scientists have used devices called interferometers to measure Earth’s rotation. Now, researchers at the University of Vienna have taken this a step further by using quantum entangled light particles, known as photons, to achieve the most precise measurement yet. Their groundbreaking experiment, published in Science Advances, showcases how quantum physics can enhance our understanding of Earth’s movements.
Understanding the Basics: Interferometers and Entangled Photons
What Is an Interferometer?
An interferometer is a scientific instrument that splits a beam of light into two paths, sends them in different directions, and then brings them back together. If the paths are the same length, the light waves align perfectly. However, if one path is longer or affected by movement, the waves will interfere with each other, creating patterns that scientists can analyze to detect motion or changes.
What Is Quantum Entanglement?
Quantum entanglement is a phenomenon where two particles become linked in such a way that the state of one instantly influences the state of the other, no matter how far apart they are. In this experiment, scientists used pairs of entangled photons. These pairs behave as a single unit, allowing for more precise measurements than individual particles.
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The Experiment: Measuring Earth’s Rotation with Entangled Light
The research team constructed a large Sagnac interferometer using 2 kilometers of optical fiber wound into a coil with an area of over 700 square meters. This setup allowed them to send entangled photon pairs in opposite directions around the loop. Due to Earth’s rotation, the photons traveling against the rotation experienced a slight delay compared to those moving with it. This difference caused interference patterns that the scientists could measure to determine Earth’s rotation rate.
One of the challenges was isolating Earth’s rotation signal from other potential disturbances. To address this, the team ingeniously split the optical fiber into two equal-length coils connected by an optical switch. By toggling the switch, they could effectively “turn off” the rotation signal, ensuring that their measurements were accurate and not influenced by external factors.
Why This Matters
This experiment achieved a rotational sensitivity of 5 microradians per second, the highest ever recorded using optical quantum interferometers. This level of precision is a thousand times greater than previous attempts. Beyond measuring Earth’s rotation, this technique opens doors to exploring how quantum mechanics interacts with general relativity, potentially leading to new discoveries in fundamental physics.
Looking Ahead
The success of this experiment demonstrates the potential of combining quantum physics with traditional measurement techniques. As technology advances, we can expect even more precise instruments that will deepen our understanding of the universe and the fundamental laws that govern it.
For more detailed information, you can refer to the original study published in Science Advances on June 14, 2024. (ScienceDaily)
