Experimental Deployment of a 4-State Continuous-Variable QKD System with Rate-Adaptive Error Correction in an Urban Environment

In realistic environments, continuous-variable QKD has to contend with changing channel parameters. Rate-adaptive error correction (RA-EC) can avoid the key rate losses due to deviations from the optimal working point of any given fixed-rate code. The benefits of rate-adaptivity have only recently been demonstrated for CV-QKD with a QPSK protocol [1]. In this work, we explicitly compare the key rate performance of a 4-state CV-QKD system deployed in an urban environment by using both fixed-rate and rate-adaptive implementations.