Fig. 1: The test scheme to estimate the fidelity.
From: Finite-size security of continuous-variable quantum key distribution with digital signal processing
a Example of the test functions Λm,r used in the estimation. The values of r in the figure are chosen so that the range of Λm,r is minimized for given m. In general, the minimum range of the function Λm,r becomes larger as m increases. The pair (m, r) = (1, 0.4120) was used in the numerical simulation of key rates below. b A schematic description of the usage of obtained outcomes in heterodyne measurement. In order to estimate the lower bound on the fidelity to the coherent states \(\left|\pm \beta \right\rangle\), the squared distance between the outcome \(\hat{\omega }\) and the objective point (−1)aβ (i.e., \(| \hat{\omega }-{(-1)}^{a}\beta {| }^{2}\)) is used.
