Average value

1. Jun 16, 2005

Feynmanfan

I have trouble understanding operators and observables:

Does <A> the average value of an observable and the variance depend on the state of the system? What does it have to do with the Hamiltonian?

Thanks!

2. Jun 16, 2005

dextercioby

Basically none.Yes,both the variance and the expectation value/average depend upon the quantum state.

Daniel.

3. Jun 16, 2005

shyboy

This is too general question. With respect to Hamiltonian there are two types of operators- those which commute and those which does not commute with Hamiltonian.
If we have a time independent Hamiltonian, then those operators which commute with it will have their average value constant.