Characterization and Validation of CV-QKD Systems Traceable to the SI Units

Accurate characterization and validation is essential for the performance and security of quantum communication systems. For example, in quantum random number generators (QRNGs) based on vacuum state measurements [1], [2], rigorous system characterization minimizes parameter uncertainties that could degrade output quality by causing deviations from the stochastic model underlying random number generation. Similarly, continuous-variable quantum key distribution (CV-QKD) systems, particularly those using Gaussian-modulated coherent states, rely on precise detection efficiency characterization to maintain security. Inaccurate loss assessment can introduce exploitable vulnerabilities, leaving these systems open to eavesdropping. Despite advancements in quantum technologies, a lack of metrologically sound, traceable standards for key system parameters limits their reliability and commercialization.