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B Quantum Confusion?

  1. Jul 12, 2017 #1
    I caught this on the BBC iPlayer and I'm somewhat puzzled. The report - brief though it is - seems to suggest that meaningful information can be transmitted via quantum entanglement. I've always understood this to be impossible as it would violate Special Relativity. Or can quantum entanglement - as cited here via 'teleportation' - function at subluminary speeds? Many thanks.

    http://www.bbc.co.uk/programmes/p058d6hj
     
  2. jcsd
  3. Jul 12, 2017 #2

    Nugatory

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    Staff: Mentor

    Quantum teleportation requires an ordinary classical channel that operates at ordinary subliminal speeds. At a somewhat handwavey level (google will find you more complete descriptions more appropriate for an I-level thread): we operate on the earth-bound member of the pair (taking the remote particle to an unknown state), then we send an ordinary classical message saying what we did and what the result was; that information tells the person at the other end what they need to do to their particle to take it from the unknown state it was in after our operation to the desired final state.
     
  4. Jul 12, 2017 #3

    DrChinese

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    To be clear: the headline of the link - "First object teleported to Earth's orbit" - is inaccurate and misleading. Please note:

    1. There are no objects being teleported. A photon (one of a pair) is sent at normal light speed (c) from the Earth to a satellite.

    2. There is a sense that there is instantaneous "teleportation" of a quantum property from one place to another. However, that could be from Earth to the satellite, or from the satellite to the Earth. There is no meaningful direction involved. Order of measurements is not a factor as far as anyone knows.

    3. There is no information being transmitted. The observed values are always random, so there is not a lot of information in that.

    I hope this helps.
     
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