Quantized Excitation Spectrum of the Classical Harmonic Oscillator in   Zero-Point Radiation
  We report that upon excitation by a single pulse, the classical harmonic oscillator immersed in classical electromagnetic zero-point radiation, as described by random electrodynamics, exhibits a quantized excitation spectrum in agreement to that of the quantum harmonic oscillator. This numerical result is interesting in view of the generally accepted idea that classical theories do not support quantized energy spectra. 
Wayne Cheng-Wei Huang and Herman Batelaan
quant-ph physics.comp-ph