Do p and σz Commute?

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Homework Statement


Hi

I want to find the commutator between the momentum operator p and σz, the third Pauli spin matrix. I am not quite sure how to get started on this one. Can I get a push in the right direction?

For the record, I would say that it is zero since they act on different spaces. Is this correct?


Niles.
 
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I think it's important to specify a direction for the momentum operator. I think that, if it's x-momentum and z-spin and you measure x-momentum to be zero every time then you know that the spin vector is probably in the x direction telling you for sure that z-spin is zero, meaning they don't commute.
 
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