Integrated silicon photonics for high-speed quantum key distribution

Integrated photonics offers great potential for quantum communication devices in terms of complexity, robustness, and scalability. Silicon photonics in particular is a leading platform for quantum photonic technologies, with further benefits of miniaturization, cost-effective device manufacture, and compatibility with CMOS microelectronics. However, effective techniques for high-speed modulation of quantum states in standard silicon photonic platforms have been limited. Here we overcome this limitation and demonstrate high-speed low-error quantum key distribution modulation with silicon photonic devices combining slow thermo-optic DC biases and fast (10 GHz bandwidth) carrier-depletion modulation. The ability to scale up these integrated circuits and incorporate microelectronics opens the way to new and advanced integrated quantum communication technologies and larger adoption of quantumsecured communications.