Quantization of a Constant of Motion for the Harmonic Oscillator with a   Time-Explicitly Depending Force
  The quantization of a constant of motion for the harmonic oscillator with a time-explicitly depending external force is carried out. This quantization approach is compared with the normal Hamiltonian quantization approach. Numerical results show that there are qualitative and quantitative differences for both approaches, suggesting that the quantization of this constant of motion may be verified experimentally. 
G. Lopez