lgnr
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I have to prove that [itex]\left\langle lm | \vec{\hat{r}} \times \vec{\hat{p}} | lm\right \rangle = \left\langle lm | \vec{\hat{p}} \times \vec{\hat{r}} | lm \right \rangle[/itex], where [itex]| lm \rangle[/itex] are eigenkets of angular momentum operator [itex]\hat{L}^2[/itex]
And I can't figure out a way to do this correctly. I wrote the angular momentum operator-vector in terms of its components, [itex]\hat{L_x}[/itex], [itex]\hat{L_y}[/itex] and [itex]\hat{L_z}[/itex], and only the [itex]\hat{k}[/itex] component survives the bra-ket operation, because I can write [itex]\vec{L_x}[/itex] y [itex]\vec{L_y}[/itex] in terms of ladder operators, and after lowering and rising the eigenstates, the corresponding eigenkets (except for the [itex]\hat{k}[/itex] component) cancel with [itex]\langle lm |[/itex] because of the orthogonality property of these eigenkets. Probably there is a wrong sign in the problem statement. Looks trivial in that case, but I want to know your opinion.
Thanks in advance for any advice.
And I can't figure out a way to do this correctly. I wrote the angular momentum operator-vector in terms of its components, [itex]\hat{L_x}[/itex], [itex]\hat{L_y}[/itex] and [itex]\hat{L_z}[/itex], and only the [itex]\hat{k}[/itex] component survives the bra-ket operation, because I can write [itex]\vec{L_x}[/itex] y [itex]\vec{L_y}[/itex] in terms of ladder operators, and after lowering and rising the eigenstates, the corresponding eigenkets (except for the [itex]\hat{k}[/itex] component) cancel with [itex]\langle lm |[/itex] because of the orthogonality property of these eigenkets. Probably there is a wrong sign in the problem statement. Looks trivial in that case, but I want to know your opinion.
Thanks in advance for any advice.