Researchers from the University of Science and Technology of China have achieved a transformative advancement in quantum networking technology, publishing their landmark findings in both Nature and Science journals. The breakthrough addresses the fundamental challenge of signal degradation in optical fibers that has previously hindered practical implementation of large-scale quantum networks.
The research team successfully developed a comprehensive solution involving three key innovations: a long-lived trapped-ion quantum memory, a highly efficient ion-photon interface, and an experimental protocol demonstrating exceptional fidelity. These components collectively enable quantum entanglement to persist significantly longer than the time required to establish connections between network segments.
This advancement represents the world’s first demonstration of a scalable building block for quantum repeaters—devices that break long communication links into shorter, manageable segments. Quantum repeaters are essential for distributing quantum entanglement across extended distances, which is necessary for ultra-secure quantum communication and interconnecting future quantum computers.
In a parallel achievement, the team utilized similar technology to generate high-fidelity entanglement between two distant rubidium atoms. This enabled the first-ever demonstration of device-independent quantum key distribution (DI-QKD) over city-scale fiber networks. DI-QKD is considered the gold standard for secure communication as its security is guaranteed by the fundamental laws of quantum physics, remaining impervious to potential device vulnerabilities.
The team successfully implemented DI-QKD across 11 kilometers of fiber, extending the attainable distance approximately 3,000 times beyond previous results. They further confirmed the feasibility of generating secure keys over 100 kilometers, surpassing prior international records by more than two orders of magnitude.
These breakthroughs mark pivotal milestones in quantum communication and networking, signaling the transition of fiber-based quantum networks from theoretical concept toward practical implementation. The advancements position China at the forefront of quantum technology development with significant implications for global secure communications infrastructure.