Efficient Distribution of High-Dimensional Entanglement through 11 km Fibers

High-dimensional entanglement enriches our understanding of entanglement and shows many advantages in quantum communication tasks, thus its long-distance distribution is a key technology. Here we use multicore fiber to distribute four-dimensional entanglement over 11 km. The observed fidelity is F = 0.921 ± 0.001 which is feasible for high-dimensional quantum network. Then we observed the violation of high-dimensional Bell inequality (I4 = 2.635 ±0.014) and steering inequality (S4 = 1.900 ± 0.003) for a four-dimensional system over a distance of more than 10 km, and finally demonstrated four-dimensional quantum key distribution based on entanglement in principle of proof. Our work provides a prominent experimental platform for high-dimensional quantum technologies and enables the intracity high-dimensional quantum network.