The Beijing-Shanghai Backbone Network (BSBN), the world’s first long-distance quantum-secured communication route, was put into service on Aug. 30. It links the two cities with a highly-reliable and expandable secure communication expressway.

The node in Beijing will also cooperate with Micius, an experimental quantum satellite launched early last year, to lay the foundation for an integrated space-earth quantum communication network as well as a global quantum communication network. 

BSBN was developed under the leadership of the University of Science and Technology of China (USTC). Several organizations have cooperated in the construction of BSBN, including the China Cable TV Network Co. Ltd., the Shandong Institute of Information and Communication Technology, the USTC Advanced Technology Institute, and the China Bank Regulatory Commission, among others. 

What is BSBN? 

BSBN, known officially as the National Demonstration Project of Verification and Application of Quantum Secure Communication between Beijing and Shanghai, has been called the “information security expressway.”  

The inter-city quantum communication line, which measures over 2000 km and comprises 32 relay stations, connects the cities of Beijing, Jinan, Hefei and Shanghai. Data can be transferred through the network with absolute security. 

“On the basis of the original fiber line, we utilized quantum key technology to give every message a unique encryption, and then transferred [the messages] through the traditional communication network,” said CHEN Yu’ao, a professor from the University of Science and Technology of China (USTC), and also Chief Designer of BSBN. 

Relay stations were built to solve the problem of signal attenuation during the transmission of the quantum key. In contrast with traditional transmission technology, BSBN’s relay stations will not receive then resend messages in transit. As a result, the whole transfer process will remain under direct control, according to CHEN. 

Promising Prospect 

A pilot project of BSBN was launched in January in Shanghai. The network uses quantum-secured fiber lines to connect seven financial institutes in Lujiazui’s Quantum Communication Industrial Park. Already, device adjustment for two of the institutes has been completed. 

Meanwhile, a command center and a big data center are also under construction. 

As part of the project, embedded control software for high-speed detection and quantum key distribution were developed for these centers, respectively. 

Several trials for the quantum communication network are now under way. As part of this process, data is transferred from the data center to another server in the same city, with quantum encryption by USTC. “Theoretically, it is impossible for data encrypted with quantum keys to be intercepted or interpreted. This is critically important for the transfer of financial data,” said REN Changqing, manager of the ICBC Data Center Network Department, one of the units involved in the trials. 

BSBN was constructed with fiber lines at relatively low cost, offering many promising application prospects. According to Prof. CHEN, BSBN can currently provide bandwidth of 100G, with a base project cost of less than RMB 600 million. In contrast, the current cost of comparable bandwidth is RMB 2 billion. 

More quantum communication lines will be built in the future to finally form a network, according to CHEN. “The changes will take place unnoticed; people will enjoy absolute information security without even realizing it,” he said. 

Prof. LU Zhaoyang, also from USTC, said he is expecting mass practical use of quantum communication within a few years. Traditional communication network hardware will be improved, rather than replaced. By installing quantum encrypting devices such as single photon detectors and quantum gateways on both the sender and receiver of the transmission, traditional communication networks can also conduct quantum communication, with obvious security improvements.