High dimensional time-bin entanglement

High-dimensional entanglement enhances information capacity and resilience to noise and loss. Time-bin entanglement, being inherently compatible with both fiber and free-space links, serves as a leading platform for scalable quantum communication. Combining these advantages, high-dimensional time-bin entanglement emerges as a promising candidate for long-distance quantum communication. However, previous implementations of high-dimensional time-bin entanglement have relied on multiple long-path interferometers, limiting stability and scalability. Here, we demonstrate a simplified scheme that employs a single interferometer to certify high-dimensional entanglement for both continuous-wave and pulsed time-bin sources. We further evaluate the asymptotic key rate and experimentally achieve secure key generation up to a dimensionality of d=32. These results establish a practical and compact approach for realizing scalable high-dimensional quantum communication networks.