The previous record was just 100 kilometers. Now, a team of scientists from the University of Science and Technology and the Chinese Academy of Sciences has managed to transmit entangled photons from a satellite to three stations on Earth, that is, the particles conserved a quantum relationship despite being further apart. 1,200 kilometers. A milestone in quantum communications that has been collected by the journal Science.
Linking particles quantumly at a distance is not an easy task as quantum entanglement is lost as they are transmitted either through open spaces on Earth or through optical fibers. How to solve it?
Experts have used the Micius or Mozi satellite (in honor of a 5th century BC Chinese philosopher and scientist) equipped with highly specialized quantum technologies and tools. Specifically, they managed to communicate with three ground stations located in different parts of China (Nanshan in the city of Urumqi, Delingha in Qinghai and the Gaomeigu Observatory in Lijiang), setting a new record for quantum entanglement between two of them, separated by a distance of 1,203 kilometers exactly. The place is not random, since China already has several indecipherable quantum networks to link cities and institutions and this nation was considered by the journal Nature as a ‘pioneer country of quantum technology in space’.
To achieve this milestone, they subjected a laser beam from the satellite to a beam splitter, achieving two different polarized states of the beam . One was used to transmit the entangled photons and the other for reception.
According to the authors, a quantum entanglement distribution that covers large distances, such as the ones they have achieved, will have important implications for quantum teleportation and communication networks, being able to obtain hyper-secure quantum communications in the future, thanks to lasers and technologies based in satellite.
With this type of teleportation we will not be able to transfer energy or matter nor will we obtain shipments of information at a speed greater than that of light, but it will be a crucial step in research and the future of quantum communications.
Reference: Juan Yin et al. “Satellite-based entanglement distribution over 1200 kilometers”. Science, June 16, 2017. DOI: 10.1126 / science.aan3211
Image credit: Juan Yin et al./Science
