On the Impact of Center Frequency Drifts on QKD Performance in WDM-based Nodes

Integrating Quantum Key Distribution (QKD) systems in existing optical infrastructure towards hybrid classical/quantum communication networks has arisen as a top priority for fiber infrastructure owners [1] . In this direction, important steps have been made using multiplexing techniques such as the recently reported record joint transmission of Continuous Variable-QKD (CV-QKD) with Wavelength Division Multiplexing (WDM) 18.3Tbps coherent data channels [2] . However, moving towards practical implementations where real-world deployments such as filtering nodes and lasers sources suffer from few GHz frequency drifts, a thorough study and a precise quantification of the impact of setups misalignments and the subsequent evaluation of the tolerance of QKD links are yet to be investigated. In this work, we attempt to focus on this setup misalignment by addressing the impact of filtering penalty in the WDM co-existence of QKD with classical bright signals.