The design of entangled source for free space quantum communications
自由空间量子通信实验中纠缠源的研制

We design and build an entanglement source suitable for free space quantum communications experiment. The coincidence counting rate after single mode fiber is 20000 cps. The entanglement visibility is more than 95% in horizontal vertical base and more than 90% in diagonal base. The Bell inequality was broken by more than 100 standard deviations in local experiment. The entanglement source satisfies the requirements for 20 km free space quantum communications experiment.