AI 中文总结
该研究首次实验验证了CV-QKD与DV-QKD系统在光纤及620米城市自由空间链路的WDM复用，实现了异构量子通信网络的实用化构建。
AI 中文摘要
未来量子通信基础设施需要在共享物理信道上服务异构用户：短距离、高吞吐量链路更适合连续变量量子密钥分发（CV-QKD），而长距离、高损耗链路仍是离散变量量子密钥分发（DV-QKD）的应用领域。将两种协议通过波分复用（WDM）技术集成在同一信道上可同时满足两种场景的需求，但二者对噪声的敏感度差异显著，使得共存问题复杂，且迄今为止尚未经过实验验证。本文报道了首个在同一光信道上同时运行两套独立的CV-QKD和DV-QKD系统的实验，使用标准C波段密集波分复用（DWDM）滤波器，对应CV-QKD的波长为1550.12 nm，DV-QKD的波长为1545.32 nm。我们在光纤和620米城市 daylight 自由空间链路上均实现了联合运行。在光纤信道中，两套系统呈现出预期的互补特性，在信道损耗为7.56 dB时达到交叉点，此时二者均能提供约1.43 Mbit/s的密钥速率；在 daylight 自由空间链路中，两套系统在随时间变化的大气衰减条件下均能维持 Mbit/s 级别的密钥速率。在所有配置中，我们均未观测到由复用引入的可测量量子比特错误率（QBER）或 excess noise 惩罚。这些结果证明，混合CV-DV WDM技术可作为异构量子通信网络的实用构建模块，使城市高吞吐量用户和长距离骨干链路可共享同一物理基础设施。
英文摘要
Future quantum communication infrastructures will need to serve heterogeneous users on shared physical channels: short-range, high-throughput links favor Continuous-Variable Quantum Key Distribution (CV-QKD), while long-reach, high-loss links remain the domain of Discrete-Variable QKD (DV-QKD). Wavelength-division multiplexing (WDM) of the two protocols on a common channel would address both regimes simultaneously, but their markedly different noise sensitivities make coexistence non-trivial and, to date, experimentally untested. Here we report the first simultaneous operation of two independent CV- and DV-QKD systems on a common optical channel, using standard C-band DWDM filters at 1550.12 nm (CV) and 1545.32 nm (DV). We demonstrate joint operation on both optical fiber and a 620 m urban daylight free-space link. On fiber, the two systems exhibit the expected complementarity, crossing over at 7.56 dB of channel loss where both deliver $\sim$1.43 Mbit/s; in daylight free-space, both sustain Mbit/s key rates under time-varying atmospheric attenuation. Across all configurations we observe no measurable multiplexing-induced penalty in QBER or excess noise. These results establish hybrid CV-DV WDM as a practical building block for heterogeneous quantum communication networks, where metropolitan high-throughput users and long-reach backbone links can be served on a single physical infrastructure.
Comments11 pages, 9 figures
