1. Zugzwang
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    17 Aug '16 21:03
    http://www.space.com/33760-china-launches-quantum-communications-satellite.html
  2. Subscribersonhouse
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    17 Aug '16 23:09
    Originally posted by Duchess64
    http://www.space.com/33760-china-launches-quantum-communications-satellite.html
    I wonder if the military people around the world will take that as a challenge to try to crack it Ala Alan Turning in WW2.
  3. Zugzwang
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    17 Aug '16 23:33
    Originally posted by sonhouse
    I wonder if the military people around the world will take that as a challenge to try to crack it Ala Alan Turning in WW2.
    As I understand it, if it works, it's supposedly 'uncrackable' in theory, based upon physics.

    And if it works, then I would expect some racists to claim that the 'backward' Chinese
    must have 'stolen' this advanced technology from the West.
  4. Cape Town
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    18 Aug '16 07:19
    Originally posted by Duchess64
    As I understand it, if it works, it's supposedly 'uncrackable' in theory, based upon physics.

    And if it works, then I would expect some racists to claim that the 'backward' Chinese
    must have 'stolen' this advanced technology from the West.
    This is the science forum, not the racism forum.
  5. Cape Town
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    18 Aug '16 07:21
    I don't understand how it would work. How would a single photon be sent through the atmosphere to a ground station without ever interacting with anything else? Or do they send lots of photons and somehow communicate back which particular ones they have received?
  6. Subscribersonhouse
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    18 Aug '16 12:18
    Originally posted by twhitehead
    I don't understand how it would work. How would a single photon be sent through the atmosphere to a ground station without ever interacting with anything else? Or do they send lots of photons and somehow communicate back which particular ones they have received?
    They don't HAVE to be visible photons, maybe they are using longer wavelengths like IR or lower, maybe even high gigahertz waves. It has to be SOME kind of photon, the only question is the wavelength.
  7. Cape Town
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    18 Aug '16 12:26
    Originally posted by sonhouse
    They don't HAVE to be visible photons,
    I realise that, but the question still stands. Can you send photons of any kind, from space to a receiver without any interaction, or am I misunderstanding something?
  8. Subscribersonhouse
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    18 Aug '16 13:50
    Originally posted by twhitehead
    I realise that, but the question still stands. Can you send photons of any kind, from space to a receiver without any interaction, or am I misunderstanding something?
    It might be like you said, millions of photons simultaneously and the ones intact used at the other end.

    I know it is possible to send this kind of photon through optical fiber at least a hundred kilometers which of course is a lot milder transmission media than atmosphere but the Chinese have claimed to be able to do so.

    Of course they may be just lying and having a belly laugh at the hooplaw generated.
  9. Cape Town
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    18 Aug '16 14:10
    Originally posted by sonhouse
    Of course they may be just lying and having a belly laugh at the hooplaw generated.
    I am sure it is genuine, its just that I don't understand it. I'll have to do some research.
  10. Subscribersonhouse
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    18 Aug '16 15:34
    Originally posted by twhitehead
    I am sure it is genuine, its just that I don't understand it. I'll have to do some research.
    Maybe there is a paper in there somewhere.
  11. Zugzwang
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    18 Aug '16 19:36
    Originally posted by sonhouse to Twhitehead
    It might be like you said, millions of photons simultaneously and the ones intact used at the other end.

    I know it is possible to send this kind of photon through optical fiber at least a hundred kilometers which of course is a lot milder transmission media than atmosphere but the Chinese have claimed to be able to do so.

    Of course they may be just lying and having a belly laugh at the hooplaw generated.
    The DPRK (North Korea) has claimed to be able to launch missiles from submarines underwater,
    though many critics suspect that the missiles were fired from stationary platforms slightly underwater.
    In that case, the DPRK would be bluffing in order to exaggerate its military might.

    In this case, I don't see what China would have to gain by bluffing. As I understand it,
    this quantum communications satellite may be experimental. The Chinese engineers
    who designed it hope that it will validate their theories. Even if does not work, I see no
    reason why China would spend much money and draw much attention to a project that
    their experts supposedly *already* knew would fail.
  12. SubscriberAThousandYoung
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    18 Aug '16 23:27
    Originally posted by Duchess64
    As I understand it, if it works, it's supposedly 'uncrackable' in theory, based upon physics.

    And if it works, then I would expect some racists to claim that the 'backward' Chinese
    must have 'stolen' this advanced technology from the West.
    This is a joint project with Austria.
  13. Zugzwang
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    19 Aug '16 00:371 edit
    Originally posted by AThousandYoung
    This is a joint project with Austria.
    http://www.en.wikipedia.org/wiki/Quantum_Experiments_at_Space_Scale

    International cooperation is common in space projects. The US government has
    excluded China, however, from participating in space projects involving the USA.

    According to Wikipedia, the spacecraft was manufactured by the Chinese Academy of Sciences.
    It's unclear what role the Austrian Academy of Sciences has in this project.
    There's no known objective reason to assume that Austria is the technology leader in this project.
    I note that China has previously launched many satellites without any Austrian cooperation.
  14. Subscribersonhouse
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    19 Aug '16 10:16
    Originally posted by Duchess64
    http://www.en.wikipedia.org/wiki/Quantum_Experiments_at_Space_Scale

    International cooperation is common in space projects. The US government has
    excluded China, however, from participating in space projects involving the USA.

    According to Wikipedia, the spacecraft was manufactured by the Chinese Academy of Sciences.
    It's unclear what role the A ...[text shortened]... ct.
    I note that China has previously launched many satellites without any Austrian cooperation.
    It has to be experimental so I don't think either China or Austria knows the outcome yet since it IS experimental. It's not like they have some boiler plate solution in hand. This is science not warfare.
  15. Subscribersonhouse
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    21 Aug '16 02:16
    Originally posted by twhitehead
    I don't understand how it would work. How would a single photon be sent through the atmosphere to a ground station without ever interacting with anything else? Or do they send lots of photons and somehow communicate back which particular ones they have received?
    There already has been relatively long distance work like this:

    http://phys.org/news/2012-09-km-physicists-quantum-teleportation-distance.html

    Laser beam through the atmosphere 143 km apart.
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