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A commutator relation

  1. Dec 24, 2012 #1
    What is the commutator [[itex]\hat{A}[/itex][itex]\hat{B}[/itex], [itex]\hat{C}[/itex][itex]\hat{D}[/itex]] equal to? How to distribute what's inside?
     
  2. jcsd
  3. Dec 24, 2012 #2
    =(ab)(cd)-(cd)(ab)
     
  4. Dec 24, 2012 #3

    Fredrik

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    Use the rule [A,BC]=B[A,C]+[A,C]B. It's very easy to prove, so I suggest that you do that as an exercise.
     
  5. Dec 24, 2012 #4
    Do you mean [A,BC]=[A,B]C+B[A,C]?
     
  6. Dec 24, 2012 #5

    Fredrik

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    Ah, yes of course. Thanks.
     
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