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Why is Schrodinger's Cat entangled? Or is it not?

  1. Feb 27, 2013 #1
    Why is Schrodinger's Cat entangled? Or is it not? I recently saw a poster on deviantart that said this: http://browse.deviantart.com/art/WANTED-Schrodinger-s-Cat-130508078 [Broken]
    It said it was in a superposition, that i get, but the entanglement? That i don't get.

    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 27, 2013 #2
    since you understand the first part then the rest will be easy to understand hopefully. The fact that the state of the cat (dead or alive) is unknown before opening the box makes its state a superposition of both. When the box is opened by the observer, the observer becomes entangled with the cat and this forms an observer state corresponding to the cat being dead or alive, and hence the observer state is entangled with that of the cat.
  4. Feb 27, 2013 #3


    Staff: Mentor

    Well actually in the Schrodinger's Cat thought experiment long before the box is opened decoherence has occurred transforming the pure state into an improper mixed state. Observationally there is no way to tell an improper mixed state from an actual one so its perfectly OK to assume it was in the observed state prior to observation - hey presto - issue resolved.

    Last edited: Feb 28, 2013
  5. Feb 28, 2013 #4
    Now i understand. Thanks for your time and contribution.

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