- #1
ma18
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Homework Statement
Consider a particle, with mass m, charge q, moving in a uniform e-field with magnitude E and direction X_1.
The Hamiltonian is (where X, P, and X_1 are operators):
The initial expectation of position and momentum are <X(0)> = 0 and <P(0)>=0
Calculate the expectation of position and momentum oprator in the Schrodinger picture is X (t) = (X_1, X_2, X,3)
2. The attempt at a solution
I know the Hamiltonian and the initial condition. I am doing this in the schrodinger picture, and that with the time evolution operator I can represent the ket as
|phi(t)> = U (t,0) |phi(0)>
Is H is time-independent? As P is squared and is the magnitude of the P? If so the time evolution operator can be represented as
U (t,0) = exp (-i*t*H/hbar)
Then
I can represent phi(t) in terms of those terms and phi(0) and proceed but I am not sure if that is correct.
I know that P = mv = m dx/dt so I think I can use the derivative of the expectation value of X when I get that, correct. According to the equation:
d/dt <O>_t = i/h <[H,O]>_t + <dO/dt>_t
but I have to find the expectation of the position first.
Any help would be much appreciated!