Wavelength-division multiplexed quantum key distribution on silicon photonic integrated devices

We present a compact four-channel wavelength-division multiplexed quantum key distribution (WDM-QKD) transmitter near a 1550-nm wavelength implemented on a CMOS-compatible silicon-on-insulator photonics platform. Each channel of the transmitter consists of a ring modulator and a ring multiplexer, which acts as an add-drop filter to the quantum channel. To demonstrate the device’s performance, we generate secret keys using the coherent-one-way protocol at a collective rate higher than 1 Mbps under a novel composable security framework. Our work shows the potential of exploiting multiple wavelength channels in a compact advanced photonic integrated circuit to enable high-speed quantum-secure communications.