Bayesian Phase Stabilization at the Shot-Noise Limit for Scalable Quantum Networks
Abstract
High-precision optical phase stabilization in quantum networks is fundamentally constrained by the strict photon-flux and duty-cycle limits required to avoid disturbing fragile quantum states. This challenge becomes especially critical when coordinating multiple independent light sources for multi-step quantum protocols. Here, we develop an integrated phase-stabilization framework that incorporates a Bayesian phase estimator to optimally extract information from sparse single-photon detection events. This approach outperforms conventional maximum-likelihood estimation and achieves the shot-noise limit under minimal photon flux. The framework enables real-time correction of combined phase noise from both nodal lasers and transmission fibers, facilitating a two-step excitation protocol for heralded entanglement generation between separate trapped-ion nodes via single-photon interference. Operating with a detected photon rate of approximately 1 MHz and a duty cycle less than or equal to 6.5%, the system maintains interferometric visibility greater than 97% over fiber links of 10 km and 100 km. This phase control yields deterministic ion-ion entanglement with parity contrast exceeding 85% at both distances, enabling device-independent quantum key distribution. Moreover, the resulting memory-memory entanglement at 10 km survives beyond the average time required to establish it -- a fundamental requirement for quantum repeaters. This work establishes a robust and scalable foundation for practical long-distance quantum networks.
Cite
@article{arxiv.2604.21388,
title = {Bayesian Phase Stabilization at the Shot-Noise Limit for Scalable Quantum Networks},
author = {Guang-Cheng Liu and Chao-Hui Xue and Fa-Xi Chen and Ming-Yang Zheng and Yi Yang and Li-Bo Li and Bin Wang and Bo-Wen Yang and Hai-Feng Jiang and Yong Wan and Ye Wang and Jiu-Peng Chen and Qiang Zhang and Jian-Wei Pan},
journal= {arXiv preprint arXiv:2604.21388},
year = {2026}
}