Table 1 Comparison of some notable high-rate QKD systems.

The protocol implemented by Lucamarini et al. (37) is a d = 2 time-bin BB84 protocol, where the two bases are chosen with asymmetric probability. Zhong et al. (21) and Lee et al. (23) implement high-dimensional QKD (HD-QKD) using time-bin encoding schemes.

 Protocol Loss (dB) Equivalent fiber length (km) Secret key rate (megabits/s) Security level Lucamarini et al. (37) T12 7101316 35506580 2.201.090.400.12 Collective Zhong et al. (21) HD-QKD 0.024 0.120 7.02.7 Collective Lee et al. (23) HD-QKD 0.17.612.7 03863 23.05.31.2 Collective This work HD-QKD 48101416.6 2040507083 26.211.97.713.401.07 Coherent/general*

*For the definition of coherent attacks, we refer readers to the study of Sheridan and Scarani (12).