Downconversion second-harmonic generation

The results have been recently obtained by Olsen et al. [38], and they show that even for almost vanishingly small e, which is inversely proportional to the initial mean value of the number of the pump mode photons, usually very large, the quantum fluctuations have huge macroscopic effect on the system dynamics. It is evident that the quantum noise, which is always present, is responsible for the oscillations between the two regimes of second-harmonic generation and downconversion. The period of oscillation is becoming infinite as e vanishes. 

Fig. 20 to the same distribution for the fields produced in the second-harmonic generation process shown in Fig. 13. The differences are clearly visible. The distribution for the downconverted held from the beginning develops a two-peak phase structure, which is a consequence of the two-fold rotational symmetry of the Q function for the signal mode. It is known [57,67] that for fc-photon downconversion the Q function has fc-fold rotational symmetry and the phase distribution has k peaks, at least at the initial stages of the evolution. From Fig. 20 it is also clear that when the intensity of the signal mode reaches its...

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