Above photo: Staff attend the opening ceremony of the Jing-Hu, or Beijing-Shanghai, Trunk Line, at University of Science and Technology of China in Hefei, East China's Anhui province, Sept 29, 2017/ Photo credit: Xinhua
According to a report in Chinadaily, China launched a 2,000-kilometer quantum fiber link connecting Beijing and Shanghai on September 29. This would allow unhackable communication between the cities.
This has been described as the world's longest and most sophisticated quantum link, and it will serve as the backbone connecting quantum networks in four cities: Beijing, Shanghai, Jinan in Shandong province and Hefei in Anhui province. In July it was reported that researchers at the Jinan Institute of Quantum Technology had successfully completed testing a quantum communication network connecting Communist Party and government bodies in Jinan.
The physical properties of quantum entangled particles are correlated and the correlation persists regardless of the distance separating them. Distribution of entangled particles over large distances could be used to establish unhackable communications via quantum cryptography. Any attempt at eavesdropping would be detected as a measurement on one of two entangled objects would break the entanglement correlation. Hence, it is impossible to wiretap, intercept or crack information transmitted.
During the link's launch in Beijing, Bai Chunli, President of the Chinese Academy of Sciences, made video phone calls using the quantum link with scientists and government officials in Jinan, Hefei and Shanghai, congratulating them for their hard work.
He also made the world’s first intercontinental quantum video call with Anton Zelinger, the president of the Austrian Academy of Sciences in Vienna, using Quantum Experiments at Space Scale (QUESS) or Micius, the world's first quantum communication satellite, which was launched by China last year.
Micius has been integrated into the Beijing-Shanghai link, creating the world's first space-to-ground integrated quantum network capable of sending messages via landlines and from space.
Micius has made several breakthroughs during the past few months. In June, the team from the University of Science and Technology of China led by Pan Jianwei, an academician with the Chinese Academy of Sciences behind Micius, successfully demonstrated satellite-based entanglement distribution to receiver stations separated by a distance of over 1200 km. This is the record for the greatest distance over which quantum entanglement has been achieved.
In July, the team overcame the sunlight noise issue (during daytime, the bright background sunlight prohibits quantum communication in transmission under conditions of high channel loss over long distances) and demonstrated free-space quantum key distribution over 53 km during the day.
Pan Jianwei said that in the future, Chinese scientists will improve the stability of the quantum channel, improve quantum satellites' communication efficiency and stability during the daytime, and launch high orbit quantum communication satellites
He added that China will also cooperate with Germany, Russia, Italy, Singapore and other countries to explore the practicality of a global quantum communication network. However, residential use of quantum communications would require cost reduction and could take around 10 to 15 years more.
The vast extension in the distance over which this ultra-secured quantum communication is possible now opens the door for a variety of practical, real-world applications.
The report says that during the event, two employees from the Bank of Communications completed a transaction from Shanghai to Beijing using the quantum link. The State Grid is also developing a managing application using a quantum link.
In 2009, military officials used a quantum communication hotline to orchestrate the military parade for the 60th anniversary of the founding of the People's Republic of China. In 2015, the Industrial and Commercial Bank of China used a quantum network to transmit data within Beijing.
According to Xinhua, a number of encryption communication products including quantum USB key, a protection device for mobile payments, have been introduced into the market.
The Xinhua report also quotes sources close to the quantum link project saying that China is likely to issue national standards for quantum key distribution equipment in one or two years.