1. The problem statement, all variables and given/known data There is a harmonic oscillator with charge q and sudenly we turn on external electric field E, which direction is the same as oscillator's. We need to find probability, that particles energy calculated in electric field will be in m state. n=1, m=2 2. Relevant equations 3. The attempt at a solution So I've solved Schrödinger's equation for harmonic oscillator in electric field and found needed energy eigenvalue, but I don't know how to find probability.