Generation of multiple orbital angular momentum and on-demand single photons by combining quantum dot to metalens

In recent years, remarkable progress has been achieved in generating multiple orbital angular momentum beams, primarily in classical physics, exemplified by technologies such as the vertical-cavity surface-emitting laser (VCSEL). However, the study of multiple orbital angular momentum and on-demand single photons using straightforward and efficient methods still faces limitations in the quantum domain. For example, numerous existing methods necessitate a relatively extensive optical path, posing challenges for optical integration. On-chip generation of OAM single photons lacks the versatility to manipulate various degrees of freedom simultaneously. Here, we propose a design that combines quantum dots with metalens. This method integrates phase multiplexing and spatial multiplexing techniques, enabling the generation of multiple single-photon beams with distinct topological charges and spatial separation through a simpler fabrication process. Our simulation results not only introduce a novel design paradigm but also significantly advance the ongoing research efforts related to multiple orbital angular momentum and on-demand single photons in the quantum realm.