Resonant metasurface-enabled quantum light sources for single-photon emission and entangled photon-pair generation.

Light encodes information in multiple degrees of freedom (e.g., frequency, amplitude, and phase), enabling high-speed, high-bandwidth communication through fiber optics. Unlike classical light, quantum light (single or entangled photons) can transmit quantum states over long distances without loss of coherence, thereby coherently interconnecting quantum nodes for distributed quantum entanglement. Quantum light sources are critical for developing scalable quantum networks aimed at distributed quantum computing, quantum teleportation, and secure quantum communications. However, existing quantum light sources suffer from limited integrability, insufficient spectral and spatial tunability, and inefficiencies in achieving mass-produced, deterministic, on-demand quantum light generation. These limitations significantly hinder progress toward direct, on-chip integration with quantum processing units and detectors - an essential step toward scalable quantum networks. Resonant metasurfaces that leverage photonic modes - such as Mie resonances, guided-mode resonances, or symmetry-protected bound states in the continuum - offer strong spatial and temporal confinement of electromagnetic fields, characterized by high quality factors and small mode volumes. These metasurfaces greatly enhance linear and nonlinear light-matter interactions, making them ideal for efficient on-chip quantum light generation and manipulation. Here, we describe recent advances in nanoscale quantum light sources and quantum photonic state manipulation enabled by resonant metasurfaces. We also provide an outlook on next-generation miniaturized quantum light sources achievable through materials innovations in quantum emitters, the co-design of resonant metasurfaces, and ultimately, the heterogeneous integration of emerging layered van der Waals materials with resonant metasurfaces.