Quantum-optical radiative recombination between electrons and ions analyzed with a semiclassical picture

In this work, quantum-optical radiative recombinations between electrons and ions are analyzed using a semiclassical approach without losing their specific quantum-optical nature. Under moderately strong driving field conditions, the results of the quantum-optical model are consistent with the semiclassically derived results in terms of both the spectral intensity and phase. Deviations between the two models, which are observed under extremely strong driving field conditions, are investigated in the time and frequency domains to clarify the underlying reasons. In addition, the radiative recombination dynamics between a free electron and a bare ion can be simulated using our quantum model. In recent decades, the semiclassical model combined with the classical equations of light has been used as an intuitive and powerful tool to study the macroscopic buildup of nonlinearly generated light. In this macroscopic approach, the phase information of individual atomic radiations plays an essential role. Since our model can provide spectral phases of quantum-optical lights generated from individual atoms, it is now feasible to pursue the macroscopic buildup of specific quantum-optical radiations and relevant phenomena by using the conventional approach used for the semiclassical model.