China Builds 300-km Quantum Communication Network
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Beijing: Chinese scientists have successfully constructed a 300-kilometre fully connected quantum secure direct communication (QSDC) network, marking a major breakthrough in the field, the Beijing Academy of Quantum Information Sciences (BAQIS).
In a statement to the Global Times, the BAQIS team said they developed a multipump expandable fully connected QSDC network in noisy environments, which is designed to reduce its complexity and increase the number of users while guaranteeing communication distance between users.
The quantum network represents a significant platform for the verification of the fundamental principles of quantum mechanics and the realisation of quantum communication and computation.
The development is seen as a step towards real-world deployment of QSDC systems, with potential applications in sectors requiring ultra-secure communication, such as government operations and financial transactions.
A major hurdle in QSDC development has been ensuring secure and reliable communication via quantum states, while the transmission distance and the number of users are two important factors that limit the realisation of large-scale, scalable quantum communication networks, and existing quantum network construction techniques struggle to address these challenges simultaneously.
“In our recent research, we propose a long-distance large-scale and scalable fully connected QSDC network, which employs a double-pumped structure and the introduction of extra noise to successfully realise QSDC over 300 kilometres between four users in the network in pairs,” the team said.
By using multipump technology, the team can exhibit reduced complexity. This advancement ensures that the fidelity of the entangled states shared among users post-communication remained above 85 percent, thereby robustly validating the scheme’s effectiveness and reliability over extended distances, according to the team.
The researchers reported three key technical milestones: overcoming traditional star-shaped network limitations to achieve scalable full connection, extending transmission distances to 300 kilometres through optimised entangled light source preparation, and establishing an error correction mechanism based on quantum state reconstruction to ensure stable multi-node communication.
