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Homework Help: Question about commuting operators

  1. Oct 26, 2009 #1
    If A is an operator, is it correct/allowed to say:
    [tex]Ae^{iA} = e^{iA}A[/tex]

    Thanks
     
  2. jcsd
  3. Oct 26, 2009 #2

    Ben Niehoff

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    Science Advisor
    Gold Member

    Think of how [itex]e^{A}[/itex] is defined.
     
  4. Oct 26, 2009 #3
    Ah yes, so since [tex]e^{A}[/tex] is defined with a power series [tex]e^{A} = 1 + A + \frac{A^{2}}{2!} + \frac{A^{3}}{3!} + ...[/tex] and A commutes with itself then A would commute with [tex]e^{A}[/tex]
    Thanks!
     
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