Continuous variable subcarrier wave quantum key distribution with discrete modulation: mathematical model and finite-key analysis

In this paper we propose a continuous-variable subcarrier wave quantum key distribution scheme with homodyne detection and present its security analysis in the finite-size regime. We calculate a lower bound on the secret key rate for the system under the assumption that the quantum channel noise is negligible compared to detector dark counts, and an eavesdropper is restricted to collective attacks. Our calculation shows that the current realistic system implementation would allow distributing a secret keys over channels with losses up to 9 dB.