Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Driven quantum mechanical harmonic oscillator

  1. Jan 18, 2010 #1

    I just calculated the quantum mechanical harmonic oscillator with a driving dipole force [tex]V(x,t) = - x S \sin(\omega t + \phi)[/tex]

    I used the Floquet-Formalism. Then I calculated the mean expectation value, in a Floquet-State, of the Hamiltonian over a full Period T indirectly by using the Hellmann-Feynman Theorem.

    What I've got reads:

    \overline{H_\alpha} = \hbar \omega_0 \left( \alpha + \frac{1}{2} \right) - \frac{S^2}{4m} \frac{(\omega_0^2 + \omega^2)}{(\omega_0^2-\omega^2)^2}

    So the first Term is the Energyeigenvalue of the "stationary" harmonic oscillator and the other term accounts for the perturbation mentioned above, which is always positive and therefore lowers the enery with a singularity at [tex]\omega_0 = \omega[/tex].

    Now to my question. Is it physically possible to get a negative energy expectation value around [tex]\omega_0[/tex]?

    Thanks and greetings.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted