QUANTUM TELEPORTATION IN SPACE

SUMMARISED

Researchers in China have teleported a photon from the ground to the satellite orbiting more than 500 km above.

In 2017, A Long March 2D rocket took off from the Jiuquan Satellite Launch Center in the Gobi Desert and placed a satellite called Micius, named after an ancient Chinese philosopher who died in 391 B.C., in a sun-synchronous orbit so that it passes over the same point on earth at the same time each day.

Micius is highly sensitive photon receiver that allows scientists to test the technological building blocks for various quantum feats such as entanglement, cryptography and teleportation.

Teleportation relies on the phenomenon of entanglement. This occurs when two quantum objects, such as photons, form at the same instant and same point in space and so are described by the same wave function. Interestingly this shared existence continues even when the photons are separated by vast distances. So, a measurement on one immediately influences the state of the other regardless of the distance between them.

To perform the experiment, the team created entangled pairs of photons on the ground at a rate of about 4,000 per second. They then beamed one of these photons to the satellite, which passed overhead every day at midnight. They kept the other photon on the ground.

Photons interact with matter in the atmosphere or inside optical fibers causing the entanglement to be lost. To minimize the amount of atmosphere in the way the team set up its ground station in Ngari in Tibet at an altitude of over 4,000 meters. So the distance from the ground to the satellite varies from 1,400 kilometers when it is near the horizon to 500 kilometers when it is overhead ensuring that the photons travel mostly through the vacuum.

Teleportation is a building block for a wide range of technologies. “Long-distance teleportation has been recognized as a fundamental element in protocols such as large scale quantum networks and distributed quantum computation,” says the team.

This is the first time that an object has been teleported from earth to orbit that sets the stage for much more ambitious goals in the future. “This work establishes the first ground to satellite up-link for faithful and ultra-long-distance quantum teleportation, an essential step toward global-scale quantum internet,” says the team.

Reference: Emerging Technology from arXiv July 10, 2017, MIT Technology Review https://arxiv.org/ftp/arxiv/papers/1707/1707.00934.pdf