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Homework Help: Energies of a Quantum Harmonic Oscillator

  1. Nov 3, 2011 #1
    Hey guys

    I was just looking over a past homework problem and found something I'm not too sure on -

    A particle is in the ground state of a Harmonic potential V (x) = 0.5mω2x2

    If you measured the energy, what are the possible results, and with what

    Now I know the answer to this is 0.5*hbar*ω and 100%. But I'm just a bit confused about when the formula for calculating this energy value can be applied.

    E = 0.5*hbar*ω(n+0.5)

    When can we use that? ^ Is it just for quantum harmonic oscillators or is it for all Quantum systems?

  2. jcsd
  3. Nov 3, 2011 #2
    If the state of the particle is the nth eigenstate, then you can use that last formula. When it is in the ground state, it still holds with n=0. When you are given some initial wave function that is not one of the eigenstates, you need to calculate the c values with fourier's trick, and then express the initial state as a linear combination of the eigenstates. Then the time dependent wave function is gotten by attaching the standard time dependence to each piece of the summation.
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