Quantum coms?

Aliette de Bodard @ 11-09-2010

Apparently, China has managed to make quantum “teleportation” work, using a blue laser over a range of 16km–thus paving the way for extra-secure communication. Basically, they used entangled particles: every modification to the state of one is reflected instantly in the other.
Pretty darn cool. No idea how close to feasible we are (probably further off than the article implies), but that’s a neat application of quantum physics.

The security of using quantum teleportation to distribute cryptographic keys, on the other hand, is upheld by the laws of physics and has a seemingly infinite time horizon. These keys cannot currently be detected and cracked even with the help of the most powerful computers. Owing to the Heisenberg Uncertainty Principle, the quantum states of photons cannot be observed without changing the state of the particle, which has the result of immediately informing the sender and receiver of any eavesdropping. Quantum communication can thus be used to send the most sensitive information, including keys to decode encrypted data sent over less secure means.

(more on quantum cryptography here at Wikipedia, and here at pcrypto. The last is great, though it’s mostly research papers).

Aliette de Bodard is a Computer Engineer who lives and works in France. When not wrestling with Artificial Intelligence problems (aka teaching computers how to analyse what they see), she writes speculative fiction. She is the author of the Aztec fantasy Servant of the Underworld from Angry Robot, and has had short fiction published in Asimov’s, Interzone and the Year’s Best Science Fiction.

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2 Responses to “Quantum coms?”

  1. SMD says:

    The skeptic in me is wondering if this is another instance in which the Chinese government has stepped in and manipulated the truth to make a less-than-glamorous story seem, well, glamorous. Such as what happened with their space program, or during the Olympics, etc. Maybe they did it, but considering the history of manipulation there, I’m less inclined to think it’s true…

  2. Aliette de Bodard says:

    I asked my husband, who specialised in quantum coms before he changed careers, and he said that it didn’t surprise him (while not being an extraordinary achievement per se, just one more step on the road to quantum information transmission). The US, as has been noted, has already done something much on the same register, and my husband didn’t see why China would be lagging behind. He did emit a lot of doubts on the immediate applications, which I share (ie for satellite coms, the satellite would be overhead for only a fraction of a moment, not long enough to really send much information, plus there’s the dispersion by the ozone layer when you fire your laser vertically instead of horizontally). But he didn’t leap up and protest it was infeasible, so I’d tend to think it’s true, or at least true-ish.