Nonlinear photonics has provided a scientific cornerstone for a majority of modern technology during the past half-century, such as diversifying laser wavelengths, manufacturing nanostructures, and guiding the design of telecommunication systems.
Moreover, it keeps supporting the emergence of novel applications, including high-resolution spectroscopy, atomic clocks, and especially quantum technology. However, in photonic quantum state engineering, current recipes for design and modeling
are impotent in specific quantum applications, for which advanced techniques are urgently needed. In this dissertation, the quantum-level interplay between the linear response of integrated photonic devices and multiple nonlinearities within
the system has been investigated in detail. We utilize these interactions to manage the generation of limit-breaking quantum photonic states, including customized temporal-spectral entanglement, high-brightness quantum sources, and high-purity
quantum states.