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B What kind of difference would particles have?

  1. Jun 15, 2017 #1
    In quantum mechanics there is a no cloning rule, so you cannot have two things that are exactly the same. So that must mean that all particles are different. So what kind of unique properties can individual electrons or protons have?
     
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  3. Jun 15, 2017 #2

    Orodruin

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    You have misunderstood the no-cloning theorem. It states that you cannot create an identical copy of a quantum state. Electrons are indistinguishable.
     
  4. Jun 15, 2017 #3
    so basically the no-cloning rule does not apply to individual particles?
     
  5. Jun 15, 2017 #4

    Orodruin

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    I think what you have misunderstood is the meaning of "quantum state" and "create a copy".
     
  6. Jun 15, 2017 #5
    can you please elaborate?
     
  7. Jun 15, 2017 #6

    Orodruin

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    It is a theorem about the interaction between identical quantum systems. It says that there is no process by which you can start with an arbitrary state and end up with both systems in that state.
     
  8. Jun 15, 2017 #7
    so it basically says when you teleport an object, the original is forced to change.
    Why is that though?

    Also I am sorry this must be painful describing this to me.
     
  9. Jun 15, 2017 #8

    Orodruin

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    To explain that would require going quite far beyond B-level.
     
  10. Jun 15, 2017 #9

    Vanadium 50

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    It says no such thing.

    Your threads are difficult. I have avoided them, and I expect others do as well. The problem is that you start off with a misconception, and despite efforts to correct it, you stick with it. I think things would go smoother and you would get more out of PF if when you get a reply suggesting you have a misconception, to examine that misconception rather than sticking with it. Otherwise, you will just frustrate people, and frustrated people don't bother replying.
     
  11. Jun 15, 2017 #10

    Nugatory

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    That's one of the consequences of the no-cloning theorem, but that theorem is much more general and applies to many situations other than quantum teleportation. (Also, you should be aware that quantum teleportation is something very different than the popular understanding of the word - there's no "something dematerializes here and rematerializes there" stuff going on).
    There's a proof of the no-cloning theorem here: https://en.wikipedia.org/wiki/No-cloning_theorem#Theorem_and_proof. That may not be much help in a B-level thread, but there's no easier answer; until somewhere after your second year of a college physics program you'll just have to take people's word for it that has to be that way.
     
    Last edited: Jun 15, 2017
  12. Jun 15, 2017 #11

    bhobba

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    That's true.

    But at a lay level you can imagine it as allowing you to evade the uncertainty principle. If you could clone exactly then you could measure position in one exactly and momentum in the other exactly. Since they are cloned you know position and momentum exactly for both.

    But that is simply a hand-wavy lay reason eg it's not really the proper use of the uncertainty principle - but its exact meaning is not lay friendly either.

    Thanks
    Bill
     
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