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Communication using quantum entanglement

  1. Oct 26, 2007 #1
    As I understand it FTL communication via quantum entanglement would be impossible since it violates causality, but would it be possible to transfer information using QE slower that the speed of light? I recall reading something like that the receiver would not be able to tell whether the transmitter has done anything to his part of the entangled system and thus wouldn't be able to distinguish between the transmitter sending him information and a random measurement. Is this correct? Thanks.
  2. jcsd
  3. Oct 27, 2007 #2
    You could only transmit information via entanglement if you could pick which state the particle on your end ends up in after you measure it. But, the nature of quantum measurement forbids this.
  4. Oct 27, 2007 #3


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  5. Oct 27, 2007 #4


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    But you have to communicate information before you can achieve quantum teleportation!
  6. Oct 27, 2007 #5
    But since you have to transfer classical information isn't it rather pointless communication-wise? You could include everything you want to say in the classical bit you're sending anyway.
  7. Oct 29, 2007 #6
    Entanglement is also used in one form of quantum cryptography - Anton Zellinger notes that "In entanglement-based quantum cryptography it leads to the most elegant possible solution of the classic key distribution problem. It implies that the key comes into existence at spatially distant location at the same time and does not need to be transported" http://meetings.aps.org/Meeting/MAR07/Event/63945. Basically Alice and Bob construct a random key from the correlated polarization measurements.

    Maybe this is what you had in mind?
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