Nonclassical signatures of field amplitudes in eighth-Harmonic generation

Abstract

We present findings on photon antibunching and sub-Poissonian photon statistics in both the fundamental (pump) and harmonic modes, investigated up to first- and second-order Hamiltonian interactions in the context of eighth harmonic generation (EHG). Utilising the Heisenberg picture, a generalised interaction Hamiltonian is formulated and analysed across multiple specific scenarios. Our study focuses on the emergence of photon antibunching during short interactions. Notably, third-order photon antibunching at short timescales reveals a deeper degree of nonclassicality than that seen in first- and second-order cases. Enhanced nonclassical phenomena are observed under first-order coupling interactions due to the coherent entanglement of pump and harmonic fields. Furthermore, coherent or vacuum pumping leads to noticeable photon bunching in the harmonic mode. Sub-Poissonian characteristics intensify with increasing pump photon counts, emphasising that higher-order interactions significantly support the generation of nonclassical states. Minimising the second-order correlation function remains pivotal in quantum optics to realise photon antibunching.