我国成功构建300公里全连接量子直接通信网络

Core Viewpoint - The research teams from Shanghai Jiao Tong University and Shanghai University of Electric Power have made significant advancements in quantum direct communication, proposing a scalable architecture for long-distance quantum direct communication and successfully establishing a 300-kilometer quantum direct communication network among four nodes [1][2]. Group 1: Research Achievements - The quantum direct communication theory was first introduced in 2000 by teams from Tsinghua University and Beijing Quantum Information Science Research Institute, with subsequent experimental validations by various institutions [1]. - In 2021, the Shanghai Jiao Tong University team achieved a 40-kilometer quantum direct communication network involving 15 nodes, laying a solid foundation for further advancements [2]. - The recent study utilized a dual-pump optical parametric down-conversion technique to create a quantum entanglement distribution system with high anti-interference capability, maintaining a quantum state fidelity of over 85% after communication [2]. Group 2: Technical Breakthroughs - The research achieved three main technical breakthroughs: overcoming the limitations of traditional star network architecture to enable scalable full connectivity, enhancing transmission distance to 300 kilometers through optimized entangled light source preparation, and establishing an error correction mechanism based on quantum state reconstruction to ensure multi-node communication stability [2]. - After a 300-kilometer transmission, the photon pair count at the receiving node remained at 300-400 Hz, indicating a theoretical communication rate of several bits per second after encoding [2]. Group 3: Future Applications - The successful construction of this quantum communication network system lays a crucial foundation for practical applications in fields requiring high information security, such as military command, government communication, and financial transactions [3].