DV-QKD in coexistence with classical channels in multicore fiber

The simulation results demonstrate the possibility of simultaneous transmission of the classical and quantum channels in the same multicore fiber using space division multiplexing. Low crosstalk between the fiber cores helps to isolate the T12 DV-QKD channel (that propagates in one of the fiber cores) from the detrimental effect of the spontaneous Raman scattering of the classical channels propagating in both directions in each other core. The simulation illustrates how QBER and secret key rate degrade with an increase of the classical channel power for the specified crosstalk level between the fiber cores. The simulations examine the system over a wide range of classical channel powers (which may exceed typical values) to find an upper bound under which secure communication is still possible.本仿真结果证实，采用空分复用（space division multiplexing）技术可在同一多芯光纤（multicore fiber）中同时传输经典信道与量子信道。光纤纤芯间的低串扰，可将在单根纤芯中传输的T12 DV-QKD信道，与其余纤芯中双向传输的经典信道所产生的自发拉曼散射（spontaneous Raman scattering）的有害影响予以隔离。本次仿真展示了，在指定的纤芯串扰水平下，量子比特错误率（Quantum Bit Error Rate, QBER）与密钥生成率（secret key rate）如何随经典信道功率提升而发生劣化。本仿真在覆盖大范围经典信道功率取值（该范围可超出典型应用的常规取值）的条件下对系统展开研究，以探寻仍可实现安全通信的功率上限。