Phys.org April 20, 2022
Researchers in China have designed an elaborate physical system and protocol with much enhanced performance for quantum secure communication. The design increased the secrecy capacity greatly by achieving an ultra-low quantum bit error rate of <0.1%, one order of magnitude smaller than that of existing systems. Compared to previous systems, the proposed scheme used photonic time-bin and phase states, operating at 50 MHz of repetition rate, which can be easily upgraded to over 1 GHz using current on-the-shelf technology. Their experiments demonstrated that the proposed system could tolerate more channel loss, from 5.1 dB, which is about 28.3 km in fiber in the previous scheme, to 18.4 dB, which corresponds to fiber length of 102.2 km. According to the researchers, intercity quantum secure direct communication through fiber is feasible with present-day technology…read more. Open Access TECHNICAL ARTICLEÂ
Illustration of the proposed protocol. Credit: Light: Science & Applications volume 11, Article number: 83 (2022)Â