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I Schroedinger Cats and Consistent Histories

  1. Nov 9, 2017 #1
    In https://arxiv.org/abs/quant-ph/9810016, Griffiths says the following about his consistent histories interpretation of QM:

    1. An experiment can be described in many ways that are equally valid. Each such narration / description is called a consistent family of possible histories.

    2. To answer any particular question about the experiment, one has to choose a family of histories that actually helps to answer that question. There may be more than one useful family for a given question.

    3. Some consistent families involve MQS (Macroscopic Quantum Superpositions), aka Schroedinger cat states.

    Now my question is, for any given question, can we be sure of finding a relevant family that DOES NOT involve an MQS?
     
  2. jcsd
  3. Nov 9, 2017 #2

    bhobba

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    No.

    But such are very very rare. Another name for consistent histories is decoherent histories. Just about everything out there is in contact with the environment, which effectively decoheres them so they are not in so called Schrodinger Cat states.

    As an aside I know theoretically what a Schrodinger Cat state is, but have never even heard an actual example of one - I am sure they exist - but what actually is one? Maybe the classical double slit with one photon at a time - the photons are not decohered, but that is hardly macroscopic. Note in the Schrodinger Cat thought experiment since a live cat, in order to be alive, is in contact with an environment - ie breaths air, sweats etc. So it is not and can never be in an actual Schrodinger Cat state - yet that's what they call it - interesting isn't it.

    Added later:
    Found the following:
    http://photonics.anu.edu.au/qoptics/Research/schrodingercatst.html

    So that is a definite example - but it's rather contrived. I think all such states likely are - but I am not 100% sure. Strange again isn't it.

    Thanks
    Bill
     
  4. Nov 10, 2017 #3
    Thank you!
     
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