Raman quantum memory of photonic polarized entanglement

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. Here, two storage experiments using the Raman scheme are reported: (1) heralded single-photon entanglement of the path and polarization storage in a cold atomic ensemble, and (2) polarization entanglement storage in two cold atomic ensembles. The experimental data clearly show that the quantum entanglement is preserved in this memory platform. Our work shows great promise for the establishment of quantum networks in high-speed communications.