ABSTRACT Integrated time‐bin‐entangled photon‐pair source with cavity‐enhanced nonlinear optical processes is essential for quantum information technologies. However, microcavities with a high quality factor inherently introduce a trade‐off between generation efficiency and photon bandwidth, which hinders the development of high‐speed quantum networks with an integrated source. Here, we address this challenge by optimizing the nonlinearity property of the material and the geometry of the integrated microring resonator with a 4H‐silicon carbide platform. Operating at a loaded quality factor of ‐ spectral bandwidth of and pumped with 300‐ps double pulses separated by 1.25 ns at a repetition rate of , the device achieves a time‐bin‐entangled photon‐pair generation rate of . A raw visibility of is measured, showing a violation of Bell's inequality by more than 138 standard deviations, and a fidelity of is obtained by quantum state tomography. These results provide a scalable pathway to an efficient and broadband time‐bin entangled quantum light source, overcoming intrinsic limitations of cavity‐based designs and advancing integrated platforms for future quantum communication networks.
Zeng et al. (2026) studied this question.