Composable security analysis of an experimental continuous-variable quantum key distribution system operating with polar codes

The integration of a continuous-variable (CV) quantum key distribution (QKD) system with a transmitted local oscillator into existing telecommunication infrastructure is presented and analyzed in terms of both its experimental implementation and theoretical security aspects. We studied the operation of the proposed system for its practical parameters and obtained the secure key. The choice of an algorithm for post-processing is also discussed and justified. Composable security analysis is fulfilled in the trusted noise paradigm for the real parameters of the proposed continuous-variable quantum key distribution system, with unambiguous state discrimination and photon-number-splitting attacks addressed in detail. The implemented CV-QKD system can be used to create metropolitan area quantum networks for both commercial and public organizations’ purposes requiring frequent secure key updates, as well as for scaling backbone quantum networks.