基于高损耗信道的纠缠分发实验模拟

Experimental simulation of quantum entanglement distribution over a high-loss channel

实验模拟了总信道损耗70dB的纠缠分发和Bell不等式的破坏,相当于纠缠光子对从轨道高度350km的卫星上发射(口径13.5cm),到仰角大于10°的地面站被接收(口径100cm)的信道损耗[11],模拟纠缠分发距离超过千公里;并且通过理论和实验研究,明确了高信道衰减下量子纠缠分发的关键技术突破点,首先必须降低系统暗计数和提高系统时间分辨,在此基础上提高纠缠源的亮度,系统将能容忍更高的信道衰减,实现更远的通信距离.

We experimentally simulate entanglement distribution and demonstrate the violation of Bell’s inequality over 70 dB channel loss. Imaging a communication system which is composed of a satellite-based entangled photon source at a height of 350 km, two satellite-based transmitting telescopes each with a diameter of 13.5 cm, and two receiving telescopes each with a diameter of 100 cm on the ground station. At a minimum ground elevation angle of 10°, the attenuation for optical links to two ground stations over thousand kilometers is comparable to that we have achieved. Furthermore, theoretical and experimental studies demonstrate the key technology researches in entanglement distribution with high loss. First of all, we should reduce the dark noise and raise the time resolution of the system. On this basis, with the brightness enhancement of the source, the system is tolerant of higher link attenuation and long communication distance.