Joint photon-number probability distribution of the input pump (coherent radiation) and the sixth harmonic for two different mean pump photon numbers (red and black). In the case of the coherent pump the joint photon-number distribution is Gaussian, while the photon statistics in the BSV case show non-trivial features. N_{{nω}, total}^{({\mathrm{bsv}})}, total photon number of the n th harmonic, generated by BSV; N_{{nω}, total}^{({\mathrm{coh}})}, total photon number of the n th harmonic, generated by coherent punp; N nω, n th harmonic photon number; {N_{ω}}, mean photon number of the pump; {{N }}, same as {N_{ω}} ; {N_{{6}{ω}}}, mean photon number of the 6th harmonic.
