China Takes Lead in Quantum Space Race

A Chinese satellite has used quantum entanglement to communicate with three ground stations, taking the lead om creating secure communications systems that cannot be hacked.

In a landmark study, a team of Chinese scientists using an experimental satellite has tested quantum entanglement over unprecedented distances, beaming entangled pairs of photons to three ground stations across China—each separated by more than 1,200 kilometers. The test verifies a mysterious and long-held tenet of quantum theory, and firmly establishes China as the front-runner in a burgeoning “quantum space race” to create a secure, quantum-based global communications network—that is, a potentially unhackable “quantum internet” that would be of immense geopolitical importance. The findings were published Thursday in Science.

“China has taken the leadership in quantum communication,” says Nicolas Gisin, a physicist at the University of Geneva who was not involved in the study. “This demonstrates that global quantum communication is possible and will be achieved in the near future.”

The concept of quantum communications is considered the gold standard for security, in part because any compromising surveillance leaves its imprint on the transmission. Conventional encrypted messages require secret keys to decrypt, but those keys are vulnerable to eavesdropping as they are sent out into the ether. In quantum communications, however, these keys can be encoded in various quantum states of entangled photons—such as their polarization—and these states will be unavoidably altered if a message is intercepted by eavesdroppers. Ground-based quantum communications typically send entangled photon pairs via fiber-optic cables or open air. But collisions with ordinary atoms along the way disrupt the photons’ delicate quantum states, limiting transmission distances to a few hundred kilometers. Sophisticated devices called “quantum repeaters”—equipped with “quantum memory” modules—could in principle be daisy-chained together to receive, store and retransmit the quantum keys across longer distances, but this task is so complex and difficult that such systems remain largely theoretical.

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  • JamesG

    Sigh… this is quantum encryption not entanglement. its based more on quantum maths than actual measuring anything. And it still has horribly unpractical loss and error rates. But I’m sure this will float tons of grants…

  • Ryan Faith
  • JamesG

    paywalled.

  • Ryan Faith
  • JamesG

    Yup.

    The greatest disservice the early quantum theorists did was get philosophically ahead of themselves and depicted superposition as the actual state of particles, when it is not at all. And people have been falling down that rabbit hole ever since…

  • Andrew Tubbiolo

    The Scientific American article makes mention of some capabilities that if working present an interesting possibility. Namely …..

    1) The ability to entangle two photons, keep one on the ground and transmit the other.
    2) The ability to receive an entangled photon, and put it into a storable form. That’s what a a quantum ‘repeater’ has to do.

    The key question is how long can that information/photon be held in storage? It must be some period of time as somehow the q-state of the stored photon is read, re-created, and re-transmitted. If that storage time is long, it implies the ability to create a buffer of photons that can be held in storage. If that time can he on the order of hours, or days, a ground station could create a stream of photons, store one set on Earth, transmit their twins to a buffer on a spacecraft in deep space. Then on a scheduled basis destructively write-to/read their respective buffer locations on schedule. Those written-to/read photons in the buffer that are destructively read/written-to are replaced by a new pair that are generated/arrive on schedule. If you don’t count the fact that the transmitted photons have travelled at c to the spacecraft buffer space it seems a way might be opening for FTL transmission of information across space.

    As for quantum encryption … yes, it’s secure, but it can be so easily jammed…..

  • savuporo

    China has taken a lead in many other technology races, even though it’s not widely reported or understood.