Improving Parameter Optimization in Decoy-State Quantum Key Distribution

Figure 2

Examples of (a) nonconvex key rate function with respect to signal intensity and decoy intensity in the BB84 protocol, (b) discontinuity of first-order derivatives of key rate function with respect to Alice’s decoy intensity and Bob’s decoy intensity in asymmetric MDI protocol, and narrow search spaces over long transmission distances of (c) and (d) with respect to each users’ signal intensity and decoy intensity in RFI-MDI protocol. In each example, the boundary line was obtained by sweeping the and parameters.

(a)

(b)

(c)

(d)