III族窒化物量子ドットとナノフォトニック共振器のコデザインによるオンチップ単一光子源の非識別化

Room-temperature solid-state III-nitride quantum dots (QDs) are an emerging platform for UV-visible quantum light sources. Despite the potential, a unified theoretical framework linking QD microscopic dynamics with nanophotonic structures remains unexplored. In this study, we develop a comprehensive computational study that bridges quantum mechanical modeling of III-nitride QDs with nanophotonic inverse design for optimized single-photon sources. By modeling the III-nitride QD dynamics as a biexciton-exciton cascade in a four-level system coupled to a cavity, we evaluate the impact of QD-cavity coupling, cavity detuning on QD dynamics, and analyze how dissipation and decoherence channels degrade photon indistinguishability. We demonstrate that by tuning the cavity resonance to the biexciton-exciton transition and engineering the Purcell factor, high indistinguishability (>99%) can be achieved in the weak coupling regime. However, entanglement concurrence is strongly limited by fine-structure splitting and cannot be recovered through Purcell enhancement alone. Guided by these insights, we use computationally efficient adjoint-based inverse design to numerically develop a suspended GaN nanobeam cavity waveguide that meets target parameters while enabling efficient photon extraction. This study reveals a fundamental trade-off between indistinguishability and photon extraction efficiency, and shows that a Purcell factor of ∼100 - with two-sided extraction efficiency of up to 66% - can be achieved with a 12-hole integrated photonic waveguide. These results provide guidelines for the co-design of integrated III-nitride quantum light sources for on-chip photonic circuits.