Chinese researchers have shattered previous limitations in quantum communication by establishing a 300-kilometer quantum secure direct communication (QSDC) network – the longest practical inter-city system of its kind. This breakthrough, led by Shanghai Jiao Tong University scientists, marks a critical step toward unhackable communication infrastructure.
The network maintains over 85% quantum state fidelity during transmission, achieving stable photon pair rates of 300-400 Hz even in noisy urban environments. Published in Science Bulletin, the innovation solves two key challenges: extending transmission range while maintaining signal integrity and enabling multi-user connectivity through a double-pumped, expandable architecture.
This achievement follows February's 104.8-km record by Beijing researchers, demonstrating China's accelerating progress in quantum technologies. QSDC systems use quantum states to detect eavesdropping attempts inherently, offering advantages over traditional encryption methods. The technology is particularly suited for financial institutions and government agencies requiring absolute data security.
Separately, an international team led by Chinese scientists recently demonstrated quantum key distribution (QKD) across 12,900 km between China and South Africa using satellite technology. Together, these advancements position quantum communication as a cornerstone of future global networks, with Chinese research institutions playing a leading role in shaping this transformative field.
