Figure 2
Oscillograms of \(V_{\text{out}}\) without DC component. Each plot shows five typical oscillograms taken under identical conditions. (a) Single-photon responses (colored or gray traces). For comparison, a typical \(V_{\text{out}}\) trace without an input pulse is plotted in black. (b) Fake “single-photon” responses under \(1550~\text{nm}\) blinding attack with \(2.4\times 10^{-18}~\text{J} \) pulse energy (i.e., about 19-photon weak coherent pulse)