- #1
keen23
- 9
- 0
Hello all!
I hope some of you are more proficient in juggling with bra-kets...
I am wondering if/when the density operator commutes with other operators, especially with unitaries and observables.
1. My guess is, that it commutes with unitaries, but I am not sure if my thinking is correct. It's like this:
[itex]\langle x|\rho U^{\dagger}|x\rangle=\langle x|U^{\dagger}\rho U U^{\dagger}|x\rangle=\langle x|U^{\dagger} \rho|x\rangle
[/itex]
Is that ok?
2.How do I determine, if a state commutes with its observable? I don't see a physical meaning in this, I'm not sure what to do...
Thanks
I hope some of you are more proficient in juggling with bra-kets...
I am wondering if/when the density operator commutes with other operators, especially with unitaries and observables.
1. My guess is, that it commutes with unitaries, but I am not sure if my thinking is correct. It's like this:
[itex]\langle x|\rho U^{\dagger}|x\rangle=\langle x|U^{\dagger}\rho U U^{\dagger}|x\rangle=\langle x|U^{\dagger} \rho|x\rangle
[/itex]
Is that ok?
2.How do I determine, if a state commutes with its observable? I don't see a physical meaning in this, I'm not sure what to do...
Thanks