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B Finding exotech

  1. Mar 2, 2017 #1
    Can we send a quantum linked signal into space and be able to tell immediately whether or not it is ever observed?
  2. jcsd
  3. Mar 2, 2017 #2


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    Staff: Mentor

    By "quantum linked system" do you mean one member of a pair of entangled particles? If so, the answer is no, there is no way of knowing whether the remote member of the pair has been observed, measured, or interacted with anything else in any way. Furthermore, the hypothetical remote observer won't even know that the particle is part of an entangled pair.
  4. Mar 2, 2017 #3
    Welcome to PF!
    We would know it was observed if we received a signal back...
  5. Mar 4, 2017 #4
    No. We link the signal to a quantum affected action. Just like the old detector slits. Any observation of the signal will flag the event. Us looking for the flags is observation of the signals. So we do it in pulses. Send, check for flags, send again and so forth. I'm not sure that it matters when it is observed, just whether or not it is ever observed. Similar to the quantum communication systems that can flag whether or not a message has been observed prior to it's observation by the recipient.
  6. Mar 4, 2017 #5
    That takes too long.
  7. Mar 4, 2017 #6
    I'm not sure about that. I think the problem is broadcasting half of these pairs out into the sky. Then we have to wait for any possible observations. What I'm saying is more real-time. (pun intended).
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