Raman quantum memory of photonic polarized entanglement

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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.

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Figure 1: Energy diagram and experimental set-up.
Figure 2: Interference of single photon for input and output.
Figure 3: Density matrices for input and output.
Figure 4: Reconstructed density matrix before and after storage.
Figure 5: Two-photon interference before and after storage.


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The authors thank Yuan Sun for reading and commenting on this manuscript. This work was supported by the National Fundamental Research Program of China (grant no. 2 011CBA00200), the National Natural Science Foundation of China (grants nos. 11174271, 61275115 and 61435011), the Youth Innovation Fund from University of Science and Technology of China (grant no. ZC 9850320804) and the Innovation Fund from Chinese Academy of Sciences.

Author information

B.S.S. conceived the idea and experiment. W.Z. and D.S.D. designed and carried out the experiments with assistance from Z.Y.Z. and S.S. D.S.D. and W.Z. carried out data analysis. D.S.D. wrote the manuscript. B.S.S. and G.C.G. supervised the project.

Correspondence to Bao-Sen Shi.

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Ding, D., Zhang, W., Zhou, Z. et al. Raman quantum memory of photonic polarized entanglement. Nature Photon 9, 332–338 (2015) doi:10.1038/nphoton.2015.43

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