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Does Quantum Computing requires MWI?

  1. Oct 24, 2015 #1
    Hello all,
    On Cosmology webstie I found the article about Time Travel,Uncertainty Principle and Many Worlds.
    Here is the quote:
    "DeWitt’s many-worlds interpretation of Everett’s work, posits that there may be a split in the combined observer–object system, the observation causing the splitting, and each split corresponding to the different or multiple possible outcomes of an observation. Each split is a separate branch or highway. A “world” refers to a single branch and includes the complete measurement history of an observer regarding that single branch, which is a world unto itself. However, every observation and interaction can cause a splitting or branching such that the combined observer–object’s wave function changes into two or more non-interacting branches which may split into many “worlds” depending on which is more probable. The splitting of worlds can continue infinitely.

    Since there are innumerable observation-like events which are constantly happening, there are an enormous number of simultaneously existing states, or worlds, all of which exist in parallel but which may become entangled; and this means, they can not be independent of each other and are relative to each other. This notion is fundamental to the concept of quantum computing."
    What bothers me is the bold part.Is MWI really fundamental/required for quantum computing?
  2. jcsd
  3. Oct 24, 2015 #2
    No, but entanglement is required. The possibility of entanglement is a fundamental property of QM, quite independent of any interpretations like MWI.
  4. Oct 24, 2015 #3
  5. Oct 24, 2015 #4


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    Science Advisor

    MWI isn't fundamental to quantum computing. Tracking all those amplitudes is fundamental to quantum computing. The many worlds interpretation happens to associate the amplitudes with "worlds", but quantum computers go on working even if that association is misguided.

    I wouldn't be surprised if studying quantum computing had a tendency to turn people into many-worlders (at least in the "Nature actually tracks amplitudes and the Born rule is not a necessary axiom" sense). People disagree about this of course (e.g. this philosophy paper claims MWI is a terrible conceptual fit for cluster-state quantum computing).

    Interpretations are never fundamental; it's the mathematical postulates that define the model and how we use that model to derive predictions in practice that matters.
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