- #1
Lindsayyyy
- 219
- 0
Hi all
Show:
[tex] (a^\dagger a)^2=a^\dagger a^\dagger a a +a^\dagger a[/tex]
wheres:
[tex] a= \lambda x +i \gamma p [/tex]
[tex] a^\dagger= \lambda x -i \gamma p [/tex]
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Well, I haven't got much.
I just tried to use the stuff given, put it into my equation and solve it, but I don't get to the right side.
I calculated a+a first
[tex] a^\dagger a ={\lambda}^2x^2 + \frac {1}{2} I + \gamma^2 p^2[/tex]
But when I now try to calculate the square of that term I get lost. If I square it I get to:
[tex] (a^\dagger a)^2= \lambda^4x^4+\gamma^4p^4 +\lambda^2 \gamma^2 (x^2p^2+p^2x^2)-\lambda^2 x^2 -\gamma^2 p^2 +\frac 1 4 I[/tex]Can anyone help me with this? I don't know what to do now/ If I'm on the right way.
Thanks for your help
edit: I is the identity matrix
Homework Statement
Show:
[tex] (a^\dagger a)^2=a^\dagger a^\dagger a a +a^\dagger a[/tex]
wheres:
[tex] a= \lambda x +i \gamma p [/tex]
[tex] a^\dagger= \lambda x -i \gamma p [/tex]
Homework Equations
-
The Attempt at a Solution
Well, I haven't got much.
I just tried to use the stuff given, put it into my equation and solve it, but I don't get to the right side.
I calculated a+a first
[tex] a^\dagger a ={\lambda}^2x^2 + \frac {1}{2} I + \gamma^2 p^2[/tex]
But when I now try to calculate the square of that term I get lost. If I square it I get to:
[tex] (a^\dagger a)^2= \lambda^4x^4+\gamma^4p^4 +\lambda^2 \gamma^2 (x^2p^2+p^2x^2)-\lambda^2 x^2 -\gamma^2 p^2 +\frac 1 4 I[/tex]Can anyone help me with this? I don't know what to do now/ If I'm on the right way.
Thanks for your help
edit: I is the identity matrix
Last edited: