Field Experiment on a Metropolitan Quantum Cryptography Network

The University of Science and Technology of China recently demonstrated a metropolitan quantum cryptography network (QCN) for use by the government in Wuhu, China. The researchers say that combining quantum key distribution (QKD) with a "one-time pad" algorithm can create unconditionally secure communication between users. With that objective in mind, the researchers built a QCN that uses a hierarchical structure with multiple levels and three different existing networking techniques.

In the Wuhu QCN, nodes with different priorities and demands are set in the central backbone net or the subnet, and assigned suitable networking methods. All QKD links are based on the BB84 protocol with decoy state method, which provides security for the network. The Wuhu QCN runs the Faraday-Michelson interferometer system, which is a unidirectional QKD scheme capable of auto-compensating for the influence of the birefringence in the transmitting channel, which can jeopardize the performance of QKD systems.

Several demonstrations of the QCN show that the stability and robustness of the QKD device is sufficient for practical applications. The researchers say that quantum cryptography should eliminate security issues such as hackers and Trojans.

From Science in China Press
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