Source: http://science.sciencemag.org/content/356/6343/1140Abstract said:Long-distance entanglement distribution is essential for both foundational tests of quantum physics and scalable quantum networks. Owing to channel loss, however, the previously achieved distance was limited to ~100 kilometers. Here we demonstrate satellite-based distribution of entangled photon pairs to two locations separated by 1203 kilometers on Earth, through two satellite-to-ground downlinks with a summed length varying from 1600 to 2400 kilometers. We observed a survival of two-photon entanglement and a violation of Bell inequality by 2.37 ± 0.09 under strict Einstein locality conditions. The obtained effective link efficiency is orders of magnitude higher than that of the direct bidirectional transmission of the two photons through telecommunication fibers.
Satellite-based entanglement over 1200 km refers to the phenomenon where two or more particles, located at a distance of over 1200 km from each other, become entangled. This means that their quantum states become correlated, even though they are physically separated.
This type of entanglement occurs through the use of satellites equipped with quantum communication technology. These satellites can generate entangled particles and then send them to separate locations, allowing for entanglement to occur over long distances.
This type of entanglement has significant implications for quantum communication and cryptography. It allows for secure communication over long distances, as any attempt to intercept the entangled particles would be immediately detected.
One of the main challenges is maintaining the entanglement over such a large distance. Any external interference or noise can disrupt the entanglement, so careful measures must be taken to combat this. Additionally, the technology and infrastructure required for satellite-based entanglement can be complex and costly.
Scientists are using this type of entanglement to study quantum mechanics and further understand the principles of entanglement. It is also being explored for potential applications in quantum computing and secure communication networks.