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Is Decoherence essentially a measurement? Then what?

  1. Aug 20, 2015 #1
    2 basic questions from a non-physicist (sigh!). Is decoherence essentially a measurement? And if so is the system of quantum particles set into the classical world forever? Or is there a mechanism by which it will evolve again into a superimposed state? Secondly, if the particle (as in the 2 slit experiment) is essentially everywhere possible at a given time, then what sense can be given to assessing the probability that the particle can be found in a specific place?
     
  2. jcsd
  3. Aug 20, 2015 #2
    Clarification: 2 basic questions from a non-physicist (sigh!). Is decoherence essentially a measurement? And if so is the system of quantum particles that has experienced decoherence set into the classical world forever? Or is there a mechanism by which it will return into a superimposed state? Secondly, if the particle (as in the 2 slit experiment) is essentially everywhere possible at a given time, then what sense can be given to assessing the probability that the particle can be found in a specific place?
     
  4. Aug 20, 2015 #3
    Decoherence is merely the entanglement of the quantum system with the quantum (assuming everything is quantum) environment. It remains in a pure, superposition, state, evolving according to the fundamental Schrodinger equation.
     
  5. Aug 21, 2015 #4

    Demystifier

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    Essentially, yes.

    The latter.

    It is not correct to say that the particle itself is everywhere. Instead, it is a non-vanishing probability of finding the particle which is everywhere.

    For example, I don't know where do you live on Earth right now. Perhaps New York? Or London? Or a small village in India? I have no idea, so I can say that you can be "everywhere". But of course, I know that you are not at all those places at once. If I find you, I know I will find you at only one of those places.
     
    Last edited: Aug 26, 2015
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