Quantum versus classical descriptions of sub-Poissonian light generation in three-wave mixing

Sub-Poissonian light generation in non-degenerate three-wave mixing is stud ied numerically and analytically within quantum and classical approaches. H usimi Q-functions and their classical trajectory simulations are analysed t o reveal a special regime corresponding to the time-stable sub-Poissonian p hotocount statistics of the sum-frequency mode. Conditions for the observat ion of this regime are discussed. Theoretical predictions of the Fano facto r and explanation of the extraordinary stabilization of the sub-Poissonian photocount behaviour are obtained analytically by applying the classical tr ajectories. Scaling laws for the maximum sub-Poissonian behaviour are found . Noise suppression levels in non-degenerate versus degenerate three-wave m ixing are discussed on different time scales compared to the revival times. It is shown that the non-degenerate conversion offers much better stabiliz ation of the suppressed noise in comparison to the degenerate process.