Universal Encoder for Phase-, Time-Bin- and Polarization-Based QKD Schemes

Here we present a QKD transmitter architecture, which enables the preparation of a fast and stable modulation of coherent light for polarisation, phase or time-bin encoded quantum states with the same setup. In contrast to other setups which are capable of preparing multiple modulation schemes [1], [2], the same optical layout and driving electronics can be used, without the need to change the optical layout or adding several additional components. Furthermore, the whole system is designed to compensate for phase drifts which would otherwise affect encoding stability and can be implemented on photonic integrated circuits (PICs).