Quantum key distribution (QKD) can greatly benefit from photonic integration, which enables implementing low-loss, alignment-free, and scalable photonic circuitry. At the same time, superconducting nanowire single-photon detectors (SNSPD) are an ideal detector technology for QKD due to their high efficiency, low dark-count rate, and low jitter. We present a QKD receiver chip featuring the full photonic circuitry needed for different time-based protocols, including single-photon detectors. By utilizing waveguide-integrated SNSPDs we achieve low dead times together with low dark-count rates and demonstrate a QKD experiment at 2.6 GHz clock rate, yielding secret-key rates of 2.5 Mbit/s for low channel attenuations of 2.5 dB without detector saturation. Due to the broadband 3D polymer couplers the reciver chip can be operated at a wide wavelength range in the telecom band, thus paving the way for highly parallelized wavelength-division multiplexing implementations.

量子密钥分配（QKD）可以从光子集成中受益匪浅，从而可以实现低损耗，无对准和可扩展的光子电路。同时，超导纳米线单光子探测器（SNSPD）由于具有高效率，低暗计数率和低抖动而成为QKD的理想探测器技术。我们提出了一种QKD接收器芯片，该芯片具有不同的基于时间的协议所需的完整光子电路，包括单光子探测器。通过利用集成波导的SNSPD，我们实现了低死区时间和低暗计数率，并演示了以2.6 GHz时钟速率进行的QKD实验，对于2.5 dB的低通道衰减没有检测器饱和的情况下，产生了2.5 Mbit / s的密钥速率。