Quantum-optical description of photon statistics and cross correlations in high-order harmonic generation

We present a study of photon statistics associated with high-order harmonic generation (HHG) involving one-mode and intermodal correlations the high photons. The aim paper is to give insight into nonclassical properties modes. To this end, we use simplified model describing an elementary quantum emitter: two-level atom. While material system extremely in description, conclusions methods may be generalized for more complex cases. Our primary interest effective HHG which exciting pulse classical, harmonics are quantized, although touch upon generalized, fully quantized as well. Evolution Mandel-parameter, antibunching, squeezing cross-correlations calculated. Results imply that respect single emitter, nonclassicality present: sub-Poissonian statistic can characterize certain optical modes, while strong anticorrelation also present.