Sub-Gbps key rate four-state continuous-variable quantum key distribution within metropolitan area

Abstract Continuous-variable quantum key distribution (CVQKD) has potential advantages of high secret rate, which is very suitable for high-speed metropolitan network application. However, the rates reported CVQKD systems are only a few Mbps over typical transmission distance so far. Here, we address fundamental experimental problems and demonstrate single-carrier four-state with sub-Gbps rate within area. In demonstrated using local oscillator, an ultra-low level excess noise obtained efficient post-processing setup designed practically extracting final secure keys. Thus, achieved 190.54 Mbps, 137.76 52.48 linear channel assuming security analysis method 233.87 133.6 21.53 semidefinite programming distances 5 km, 10 km 25 respectively. This result increases asymptotic to level, sufficient achieve one-time pad cryptographic task. Moreover, our work shows road future high-rate large-scale deployment in broadband access networks.