A research group led by Academician GUO Guangcan from Key Laboratory Quantum Information and Synergetic Innovation Center of Quantum Information & Quantum Physics of USTC are making great inroads in quantum communications based on Raman quantum memories. They firstly realized the polarized photon entanglement and the storage of photonic entanglement consisting of polarized photon of different degrees of freedom among the whole world. Their research published on 30 March on the Nature Phonotics written by DING Dongsheng and ZHANG Wei as co-first authors with “Raman Quantum memory of photonic polarized entanglement” as its title. 
“The storage of photonic entanglement is central to the achievement of long-distance quantum communication based on quantum repeaters and scalable linear optical quantum computation. Among the memory protocols reported to date, the Raman scheme has the advantages of being broadband and high-speed, resulting in a huge potential in quantum networks. To date there have been no reports on the storage of photonic polarized entanglement using the Raman protocol,” stated the two authors . 
They also mentioned that the Raman protocol was first realized experimentally by Walmsley’s group, who reported the storage of a sub-nanosecond pulse in a hot atomic vapour. This progress was significant in the realization of Raman quantum memories, despite the information carrier being weakly attenuated coherent light, and Academician GUO Guangcan’s group have realized a Raman quantum memory with true single photons using an ensemble of trapped Rb atoms. In their paper there reported two storage experiments using the Raman scheme: first, heralded single-photon entanglement of the path and polarization storage in a cold atomic ensemble; second, polarization entanglement storage in two cold atomic ensembles. The quantum entanglement was preserved in that memory platform, according to their experimental data. 
The research group gave clear experiment results which presented the successful storage of polarization entanglement. “Our work shows great promise for the establishment of quantum networks in high-speed communications.” DING and ZHANG concluded.

(GAO Kui, USTC News Center)