IT Home January 20 news, according to the "Science and Technology Daily" reported that the recent university of Science and Technology of China Academician Guo Guangcan team, Professor Han Zhengfu and his collaborators to achieve 833 km distance on the optical fiber quantum key distribution, the optical fiber quantum communication security transmission distance of more than 200 kilometers to increase the world record, to achieve thousands of kilometers of land-based quantum secure communication an important step.
The results were published online in the journal Nature Photonics. As can be seen in the figure, the research results of Guo Guangcan and Han Zhengfu's team still maintain a stable security key rate at a distance of 800km, and the signal quality on shorter lengths is higher than other tests, and the security bit rate is increased by 50-1000 times.
Quantum key distribution is based on the basic principles of quantum physics and can effectively prevent eavesdropping. Optical quantum is a natural carrier of quantum information, but the inevitable loss in the line limits the security distance of quantum key distribution, and is also one of the key factors restricting the deployment and application of wide-area quantum secure communication networks. Therefore, how to extend the security distance of direct transmission of optical quantum key distribution has become one of the most challenging difficulties and focuses at present.
IT House learned that British scientists proposed a two-field quantum key distribution protocol in 2018, breaking through the original theoretical limitations. In 2019, the team of Guo Guangcan and Han Zhengfu first proposed a two-field class protocol selected after phase-free, and verified the feasibility in a 300-kilometer fiber channel. Guo Guangcan and Han Zhengfu's team proposed an improved four-phase modulation dual-field protocol in 2021, and improved key technologies such as phase-locked frequency stabilization technology, high-bandwidth channel phase compensation technology, and single-photon detection signal screening technology with high signal-to-noise ratio, extending the secure transmission distance of optical fiber double-field quantum key distribution to 833 kilometers.
![Quantum Secure Communication: Making Communication More Secure | informal science[fig]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)