Analysis, Design and Implementation of an End-to-End QKD Link

This manuscript discusses the most relevant aspects of the practical implementation of a long-range Quantum Key Distribution (QKD) link with trusted nodes, achieving the highest possible secret key rate generation within the security and system level constraints. To this purpose, we report on recent pilot studies for the measurements of detection efficiency and source photon statistics for validating the calibration facilities (i) at telecom wavelength for realistic quantum backbone implementation through standard telecommunications grade optical fiber, and (ii) for the telecom and VIS-NIR regime. In addition, since there are circumstances when a fiber optical link may not be available, we will also discuss the characterization of a Free Space Optics (FSO) QKD link. Finally, the manuscript also discusses the problem of information reconciliation in Continuous Variable QKD (CV-QKD) scenarios.