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Chinese Physicists Achieve Quantum Teleportation Over 60 Miles 216

Posted by Soulskill
from the just-keep-the-shields-up-and-you're-fine dept.
MrSeb writes "Chinese physicists are reporting that they've successfully teleported photonic qubits (quantum bits) over a distance of 97 kilometers (60mi). This means that quantum data has been transmitted from one point to another, without passing through the intervening space. It's important to note that the Chinese researchers haven't actually made a photon disappear and reappear 97 kilometers away; rather, they've used quantum entanglement to recreate the same qubit in a new location, with the same subatomic properties as the original qubit. The previous record for transmitting entangled qubits was 16 kilometers, performed by another Chinese team back in 2010 — and perhaps most excitingly, the researchers seem confident that their system will scale up from 97km to distances capable of reaching orbital satellites, at which point we'll actually be able to build a global quantum network for all of our cryptographic needs."
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Chinese Physicists Achieve Quantum Teleportation Over 60 Miles

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  • Re:That's nothing (Score:2, Insightful)

    by Immostlyharmless (1311531) on Friday May 11, 2012 @03:10PM (#39971123)
    Old News, it's already been done :P
  • by Darth Snowshoe (1434515) on Friday May 11, 2012 @04:19PM (#39972291)

    Ah, but the abstract of the paper itself says "Over a 35-53 dB high-loss quantum channel, an average fidelity of 80.4(9) % is achieved for six distinct initial states." That sounds like a lossy channel to me. Plus, I simply don't believe it's possible to send a laser beam over X kilometers, including an atmosphere, and have them ALL reach their destination - it's a limitation of the medium.

    Also, the Physics ArXiv blog post for this paper includes this;
    "Inevitably photons get lost and entanglement is destroyed in such a process. Imperfections in the optics and air turbulence account for some of these losses but the biggest problem is beam widening (they did the experiment at an altitude of about 4000 metres). Since the beam spreads out as it travels, many of the photons simply miss the target altogether. "

    and

    "That's interesting because it's the same channel attenuation that you'd have to cope with when beaming photons to a satellite with, say, 20 centimetre optics orbiting at about 500 kilometres. "The successful quantum teleportation over such channel losses in combination with our high-frequency and high-accuracy [aiming] technique show the feasibility of satellite-based ultra-long-distance quantum teleportation," say Juan and co."

    So it looks to me as though even the paper's author is admitting some "channel losses". The question I still have is, how is it possible to distinguish channel losses from adversarial interception of photons?

  • by nedlohs (1335013) on Friday May 11, 2012 @04:25PM (#39972387)

    It shows a complete lack of understanding of science.

    And of course the actual distance will have been 100km which someone who does understand significant figures converted to 60 miles for Americans. Followed by a moron deciding to convert it to 97 km because they are scientifically illiterate.

  • Re:That's nothing (Score:2, Insightful)

    by BitHive (578094) on Friday May 11, 2012 @05:25PM (#39973275) Homepage

    When the arsonists live in the same building as you, putting out the fire may not be fair but neither is letting it all burn.

Some people have a great ambition: to build something that will last, at least until they've finished building it.

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