The South China Morning Post (December 10) disclosed that China has created a quantum communication network in space to protect its electric power grid against attacks. Part of the network links the power grid of Fujian, the southeastern province closest to Taiwan, to a national emergency command centre in Beijing. In a drill conducted in May, the ultra-secure communication line allowed central government staff to take over control of the coastal province’s power grid operation without their commands being vulnerable to tapping or manipulation by a third party. Beijing and Fujian are almost 2,000km (1,243 miles) apart. It quoted researchers working for the State Grid Information and Communication Branch -- an agency building the national power grid’s information infrastructure -- building an optical cable of that length for quantum communication could be expensive. Instead, they used Mozi, the world’s first quantum satellite, to relay the quantum key for data encryption that, by the laws of physics, could not be hacked. China launched Mozi in 2016 for scientific experiments, but in recent years the satellite has found a growing number of civilian and military applications. Lead scientist Zhao Ziyan and his colleagues said in a paper published last month in industry journal Electric Power Information and Communication Technology that applying quantum communication technology in the energy sector was prompted by national security concerns. China has the world’s largest national power grid, which last year transmitted 7,500 terawatt hours of electricity – more than the grids of the United States, India, Russia and Japan combined. The country has also built up the world’s largest renewable energy infrastructure, including wind and solar farms, and has more electric cars and smart recharging stations than anywhere else. This, according to Zhao and colleagues, made China’s power grid the most sophisticated and difficult to operate. They added that grid operators have used artificial intelligence, 5G and other cutting-edge methods to keep the rapidly expanding network efficient and stable, but an increasing reliance on machines also made the power grid more vulnerable to attacks. If a hacker were to infiltrate the power communication network and decode the commands, they could cause large-scale blackouts or other damage. Mozi could effectively pick up entangled particles of light beamed from the roof of the Beijing command centre. At the receiving end, a mobile station could pick up the quantum information relayed by the satellite and pass it to the local power grid computer. If a third party managed to intercept some light particles, it would change the physical state of other particles in the chain and trigger an alert. Mozi’s capacity to secure the network could be improved upon, given its limited bandwidth, the research paper said. Furthermore, converting quantum information to the codes used in power transmission is complex and time-consuming, and the satellite link could be established only when the satellite was passing overhead – with the quality of light signals also affected by the sun or clouds. According to openly available information, China is developing next-generation quantum satellites that could form a global constellation and work effectively in the daytime, with laser communication bandwidth reaching several gigabytes per second. Meanwhile, the government has built up large-scale quantum networks on the ground. Over the past five years, the most economically developed provinces, such as Zhejiang in the east, and politically sensitive regions including Xinjiang in the far west, have established ground-based quantum communication cables for their power grids. The government in Beijing also has an optical cable to Shanghai to strengthen its control of power management in the nation’s richest city.
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