Figure7

Figure 7. The graphs of attenuation added and its impact on the respective key parameters. (A) SKR against Attenuator(s) Added. The SKR axis scales in a logarithmic manner to illustrate the relationship between the SKR and added attenuation. The standard deviation for the SKR is included in the figure as error bars. The error bars are relatively small, indicating a relatively constant SKR; (B) QBER against Attenuator Added. The standard deviation for the QBER is included in the figure as error bars. In both plots, the error bars for the attenuation account for the insertion loss uncertainties, with the larger uncertainty indicating a combination of two attenuators. SKR: Secret key rate; QBER: quantum bit error rate.