Abstract
Quantum repeaters1,2,3,4 are essential elements for demonstrating global-scale quantum communication. Over the past few decades, tremendous efforts have been dedicated to implementing a practical quantum repeater5,6,7,8,9,10. However, nested purification1, the backbone of a quantum repeater, remains a challenge because the capacity for successive entanglement manipulation is still absent. Here, we propose and demonstrate an architecture of nested purification using spontaneous parametric downconversion sources11. A heralded entangled photon pair with higher fidelity is successfully purified from two copies of low-fidelity pairs that experience entanglement swapping and noisy channels. By delicately designing the optical circuits, double-pair emission noise is eliminated automatically and the purified state can be used for scalable entanglement connections to extend the communication distance. Combined with a quantum memory, our approach can be applied immediately in the implemention of a practical quantum repeater.
Similar content being viewed by others
References
Briegel, H., Dur, W., Cirac, J. & Zoller, P. Quantum repeaters: the role of imperfect local operations in quantum communication. Phys. Rev. Lett. 81, 5932–5935 (1998).
Dur, W., Briegel, H., Cirac, J. & Zoller, P. Quantum repeaters based on entanglement purification. Phys. Rev. A 59, 169–181 (1999).
Duan, L., Lukin, M., Cirac, J. & Zoller, P. Long-distance quantum communication with atomic ensembles and linear optics. Nature 414, 413–418 (2001).
Muralidharan, S., Kim, J., Lütkenhaus, N., Lukin, M. D. & Jiang, L. Ultrafast and fault-tolerant quantum communication across long distances. Phys. Rev. Lett. 112, 250501 (2014).
Moehring, D. et al. Entanglement of single-atom quantum bits at a distance. Nature 449, 68–71 (2007).
Chou, C.-W. et al. Functional quantum nodes for entanglement distribution over scalable quantum networks. Science 316, 1316–1320 (2007).
Yuan, Z.-S. et al. Experimental demonstration of a BDCZ quantum repeater node. Nature 454, 1098–1101 (2008).
Lee, K. C. et al. Entangling macroscopic diamonds at room temperature. Science 334, 1253–1256 (2011).
Hofmann, J. et al. Heralded entanglement between widely separated atoms. Science 337, 72–75 (2012).
Bernien, H. et al. Heralded entanglement between solid-state qubits separated by three metres. Nature 497, 86–90 (2013).
Kwiat, P. G. et al. New high-intensity source of polarization-entangled photon pairs. Phys. Rev. Lett. 75, 4337–4341 (1995).
Liu, Y. et al. Decoy-state quantum key distribution with polarized photons over 200 km. Opt. Express 18, 8587–8594 (2010).
Wang, S. et al. 2 GHz clock quantum key distribution over 260 km of standard telecom fiber. Opt. Lett. 37, 1008–1010 (2012).
Korzh, B. et al. Provably secure and practical quantum key distribution over 307 km of optical fibre. Nat. Photon. 9, 163–168 (2015).
Zukowski, M., Zeilinger, A., Horne, M. & Ekert, A. Event-ready-detectors Bell experiment via entanglement swapping. Phys. Rev. Lett. 71, 4287–4290 (1993).
Tang, Y.-L. et al. Measurement-device-independent quantum key distribution over 200 km. Phys. Rev. Lett. 114, 069901 (2015).
Yin, H.-L. et al. Measurement-device-independent quantum key distribution over a 404 km optical fiber. Phys. Rev. Lett. 117, 190501 (2016).
Bennett, C. et al. Purification of noisy entanglement and faithful teleportation via noisy channels. Phys. Rev. Lett. 76, 722–725 (1996).
Pan, J., Simon, C., Brukner, C. & Zeilinger, A. Entanglement purification for quantum communication. Nature 410, 1067–1070 (2001).
Pan, J., Bouwmeester, D., Weinfurter, H. & Zeilinger, A. Experimental entanglement swapping: entangling photons that never interacted. Phys. Rev. Lett. 80, 3891–3894 (1998).
Pan, J., Gasparoni, S., Ursin, R., Weihs, G. & Zeilinger, A. Experimental entanglement purification of arbitrary unknown states. Nature 423, 417–422 (2003).
Jennewein, T., Weihs, G., Pan, J.-W. & Zeilinger, A. Experimental nonlocality proof of quantum teleportation and entanglement swapping. Phys. Rev. Lett. 88, 017903 (2001).
De Riedmatten, H. et al. Long-distance entanglement swapping with photons from separated sources. Phys. Rev. A 71, 050302 (2005).
Halder, M. et al. Entangling independent photons by time measurement. Nat. Phys. 3, 692–695 (2007).
Goebel, A. M. et al. Multistage entanglement swapping. Phys. Rev. Lett. 101, 080403 (2008).
Yao, X.-C. et al. Observation of eight-photon entanglement. Nat. Photon. 6, 225–228 (2012).
Kim, Y.-H., Kulik, S. P., Chekhova, M. V., Grice, W. P. & Shih, Y. Experimental entanglement concentration and universal Bell-state synthesizer. Phys. Rev. A 67, 010301 (2003).
Zhao, B., Chen, Z.-B., Chen, Y.-A., Schmiedmayer, J. & Pan, J.-W. Robust creation of entanglement between remote memory qubits. Phys. Rev. Lett. 98, 240502 (2007).
Chen, Z.-B., Zhao, B., Chen, Y.-A., Schmiedmayer, J. & Pan, J.-W. Fault-tolerant quantum repeater with atomic ensembles and linear optics. Phys. Rev. A 76, 022329 (2007).
Sangouard, N., Simon, C., de Riedmatten, H. & Gisin, N. Quantum repeaters based on atomic ensembles and linear optics. Rev. Mod. Phys. 83, 33–80 (2011).
Grice, W. P., U’Ren, A. B. & Walmsley, I. A. Eliminating frequency and space–time correlations in multiphoton states. Phys. Rev. A 64, 063815 (2001).
Dixon, P. B. et al. Heralding efficiency and correlated-mode coupling of near-IR fiber-coupled photon pairs. Phys. Rev. A 90, 043804 (2014).
Marsili, F. et al. Detecting single infrared photons with 93% system efficiency. Nat. Photon. 7, 210–214 (2013).
Lita, A. E., Miller, A. J. & Nam, S. W. Counting near-infrared single-photons with 95% efficiency. Opt. Express 16, 3032–3040 (2008).
Acknowledgements
This work was supported by the National Natural Science Foundation of China (grants nos. 11274292, 11374284, 11425417, 11521063 and 61625503), the National Fundamental Research Program (grants nos. 2013CB336800 and 2013CB922001) and the Chinese Academy of Sciences.
Author information
Authors and Affiliations
Contributions
B.Z., Y.-A.C. and J.-W.P. conceived and designed the experiments. L.-K.C., P.X. and X.-C.Y. designed and characterized the multiphoton optical circuits. H.-L.Y. and C.L. developed the feedback system. T.X., Z.-D.L., H.L., N.-L.L., L.L., T.Y. and C.-Z.P. provided experimental assistance. L.-K.C., H.-L.Y., P.X., T.X. and Z.D-.L. collected and analysed the data. L.-K.C., X.-C.Y., B.Z., Y.-A.C. and J.-W.P. wrote the manuscript, with input from all authors. N.-L.L., Y.-A.C. and J.-W.P. supervised the project.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Additional information
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Electronic supplementary material
Supplementary Information
Supplementary material
Rights and permissions
About this article
Cite this article
Chen, LK., Yong, HL., Xu, P. et al. Experimental nested purification for a linear optical quantum repeater. Nature Photon 11, 695–699 (2017). https://doi.org/10.1038/s41566-017-0010-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41566-017-0010-6
- Springer Nature Limited
This article is cited by
-
Advances in quantum entanglement purification
Science China Physics, Mechanics & Astronomy (2023)
-
Quantum Zeno repeaters
Scientific Reports (2022)
-
Quantum channel correction outperforming direct transmission
Nature Communications (2022)
-
Economical multi-photon polarization entanglement purification with Bell state
Quantum Information Processing (2021)
-
Hierarchical Quantum Network using Hybrid Entanglement
Quantum Information Processing (2021)