Quantum key distribution and classical communication coherent deployment with shared hardware and joint digital signal processing

We present an experimental implementation of a joint classical/quantum transmission architecture over 10km of SMF with shared hardware at the emission and using a 64-QAM probability shaping modulation format on the quantum channel. We report a mean excess noise measurement of 0.0212 shot-noise units (SNU) on the quantum channel, leading to a secret key rate of 19.5 Mbps when taking into account finite-size effects, while no errors are accounted for on the classical channel. Thus we show that the classical data can provide solid estimates for the phase and frequency recovery of the quantum channel without adding excess-noise above the null key rate threshold. This enables us to perform CV-QKD protocols without dedicated reference signals and paves the way towards hybrid classical and quantum communication protocols.