Physics

A Photon Has Been Sent To Space Using Quantum Teleportation

Last month, Chinese researchers showed that quantum communication between Earth and space is possible, and now they have used the tech to send a photon to space using quantum teleportation.

The experiment was conducted between Micius (the Chinese quantum satellite) and a ground station. The researchers were able to transfer the unknown quantum state from one photon here on Earth to another one in space.

However, this quantum teleportation to space is not like Star Trek. Reality is a lot less glamorous. To teleport all the properties of a particle – its quantum state – some drastic measures are required.

It’s not possible to know a quantum state perfectly and it’s not possible to copy it. However, if you’re willing to destroy the particle, you can easily transfer the quantum state on another particle. The new particle will, for all intents and purposes, be equivalent to the old particle.

Quantum teleportation is a crucial requirement to create a quantum Internet that allows quantum computers to communicate between themselves. The overuse of the word quantum in the previous sentence is not to make it sound complex. Quantum computers are computers that can use the laws of quantum mechanics to perform calculations faster than even the best supercomputer we can build – and at a fraction of the size.

There are still many issues to solve to make quantum computers viable, but this research goes a long way in establishing that long-distance quantum communication is possible. The satellite was 1,400 kilometers (870 miles) away from the ground station.

“Long-distance teleportation has been recognized as a fundamental element in protocols such as large-scale quantum networks and distributed quantum computation,” the research team wrote in the paper, which is yet to be peer-reviewed. “However, the previous teleportation experiments between distant locations were limited to a distance on the order of 100 kilometers, due to photon loss in optical fibers or terrestrial free-space channels.”

Quantum communication works with the principle of entanglement, where two particles can influence each other instantaneously no matter the distance. This might at first seems a violation of special relativity since information cannot travel at the speed of light, but it isn’t. If you have entangled particles, their quantum state is shared. It doesn’t make sense (at least in quantum mechanics) to consider them as single entities.

Although entanglement is very useful (and somewhat head-scratching), it is also very fragile. You can break the quantum state easily and then the particles go back to being individuals. This is why it has been difficult to send these quantum states for more than 100 kilometers (62 miles) over air or fiber optics.

As this research shows, to create a truly global network for quantum communication, we will need quantum satellites.

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