Entangled photon pairs are of crucial importance in quantum networks. For the future demands of large-scale and secure quantum communication, integrated photon sources are highly effective solutions. Here, we report entanglement distribution over a 30 km metropolitan area using on-chip broadband silicon nanowire biphoton polarization entangled source based on a silicon-on-insulator (SOI) platform. This source generates a continuous spectrum spanning the entire C-band (4.5 THz), achieving a locally detected coincidence counts of about 154 kHz within 100GHz bandwidth, making it suitable for long-distance entanglement distribution among multiple users. By combining this source with quantum entanglement, enhanced by high-precision clock synchronization that achieves an Allan variance of 56.8 ps over 600s, we observe a violation of the CHSH inequality by 27.8 standard deviations. Our results showcase the potential of silicon photonic technology as a scalable and practical platform for quantum technologies.
@article{arxiv.2503.07198,
title = {Entanglement distribution over metropolitan fiber using on-chip broadband polarization entangled photon source},
author = {Ziheng Jiang and Wenhan Yan and Chi Lu and Yikai Chen and Wenjun Wen and Yu-Yang An and Leizhen Chen and Yanqing Lu and Shining Zhu and Xiao-Song Ma},
journal= {arXiv preprint arXiv:2503.07198},
year = {2025}
}