Sub-Poissonian photon statistics of higher harmonics: quantum predictions via classical trajectories

Second-harmonic generation in the no-energy-transfer regime can be a source of quasi-stationary sub-Poissonian light as was recently shown by Bajer et al (Bajer J, Haderka O and Perina J 1999 J. Opt. B: Quantum Semiclass. Opt . 1 529). We generalize their results for higher-harmonic generation by app lying the numerical method of Hamiltonian diagonalization and the analytica l semiclassical description of classical trajectories. The quasi-stationary behaviour of the sub-Poissonian photocount noise in the no-energy-transfer regime is explained. An approximate formula for the Fano factor is derived for arbitrary harmonics. It is predicted that the deepest quasi-stationary reduction of photocount noise in the no-energy-transfer regime is achieved in the third-harmonic generation.