Figure 4.

The secret key rate of the original detector-device-independent QKD (DDI-QKD) (black dotted line), 3d- (red dashed line), 4d- (blue dot-dashed line), and 5d-QKD with hybrid encoding (orange solid line). (a) Plot of the secret key rate r (bits/sifted pulse) vs. state error rate Q; (b) Plot of the secret key rate r (bits/sifted pulse) vs. transmission loss $\eta$ (dB). Dark count rate of single photon detectors is assumed as ${10}^{-5}$ per pulse.