Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Observation of eight-photon entanglement

Abstract

The creation of increasingly large multipartite entangled states is not only a fundamental scientific endeavour in itself1,2,3, but is also the enabling technology for quantum information4,5. Tremendous experimental effort has been devoted to generating multiparticle entanglement with a growing number of qubits6,7,8,9,10,11,12,13,14,15,16. So far, up to six spatially separated single photons10,11,12,13,14 have been entangled based on parametric downconversion17. Multiple degrees of freedom of a single photon have been exploited to generate forms of hyper-entangled states18,19. Here, using new ultra-bright sources of entangled photon pairs20, an eight-photon interferometer and post-selection detection, we demonstrate for the first time the creation of an eight-photon Schrödinger cat state1 with genuine multipartite entanglement. The ability to control eight individual photons represents a step towards optical quantum computation, and will enable new experiments on, for example, quantum simulation21,22, topological error correction23 and testing entanglement dynamics under decoherence24.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Experimental scheme for generating eight-photon Schrödinger cat states.
Figure 2: Experimental set-up.
Figure 3: Experimental results for the eight-photon Schrödinger cat state.

References

  1. Schrödinger, E. Die Gegenwartige Situation in der Quantenmechanik. Naturwissenschaften 23, 807–812, 823–828, 844–849 (1935).

    ADS  Article  Google Scholar 

  2. Einstein, A., Podolsky, B. & Rosen, N. Can quantum-mechanical description of physical reality be considered complete? Phys. Rev. 47, 777–780 (1935).

    ADS  Article  Google Scholar 

  3. Leggett, A. J. Realism and the physical world. Rep. Prog. Phys. 71, 022001 (2008).

    ADS  MathSciNet  Article  Google Scholar 

  4. Zoller, P. et al. Quantum information processing and communication. Eur. Phys. J. D 36, 203–228 (2005).

    ADS  Article  Google Scholar 

  5. Ladd, T. D. et al. Quantum computers. Nature 464, 45–53 (2010).

    ADS  Article  Google Scholar 

  6. Bouwmeester, D., Pan, J.-W., Daniell, M., Weinfurter, H. & Zeilinger, A. Observation of three-photon Greenberger–Horne–Zeilinger entanglement. Phys. Rev. Lett. 82, 1345–1349 (1999).

    ADS  MathSciNet  Article  Google Scholar 

  7. Sackett, C. A. et al. Experimental entanglement of four particles. Nature 404, 256–259 (2000).

    ADS  Article  Google Scholar 

  8. Zhao, Z. et al. Experimental demonstration of five-photon entanglement and open-destination teleportation. Nature 430, 54–58 (2004).

    ADS  Article  Google Scholar 

  9. Häffner, H. et al. Scalable multiparticle entanglement of trapped ions. Nature 438, 643–646 (2005).

    ADS  Article  Google Scholar 

  10. Lu, C.-Y. et al. Experimental entanglement of six photons in graph states. Nature Phys. 3, 91–95 (2007).

    ADS  Article  Google Scholar 

  11. Prevedel, R. et al. Experimental realization of Dicke states of up to six qubits for multiparty quantum networking. Phys. Rev. Lett. 103, 020503 (2009).

    ADS  Article  Google Scholar 

  12. Wieczorek, W. et al. Experimental entanglement of a six-photon symmetric Dicke state. Phys. Rev. Lett. 103, 020504 (2009).

    ADS  Article  Google Scholar 

  13. Radmark, M., Zukowski, M. & Bourennane, M. Experimental test of fidelity limits in six-photon interferometry and of rotational invariance properties of the photonic six-qubit entanglement singlet state. Phys. Rev. Lett. 103, 150501 (2009).

    ADS  Article  Google Scholar 

  14. Matthews, J. C. F., Politi, A., Bonneau, D. & O'Brien, J. L. Heralded entanglement for quantum enhanced measurement with photons. Phys. Rev. Lett. 107, 163602 (2011).

    ADS  Article  Google Scholar 

  15. Krischek, R. et al. Ultraviolet enhancement cavity for ultrafast nonlinear optics and high-rate multiphoton entanglement experiments. Nature Photon. 4, 170–173 (2010).

    ADS  Article  Google Scholar 

  16. Monz, T. et al. 14-Qubit entanglement: creation and coherence. Phys. Rev. Lett. 106, 130506 (2011).

    ADS  Article  Google Scholar 

  17. Kwiat, P. G. et al. New high-intensity source of polarization-entangled photon pairs. Phys. Rev. Lett. 75, 4337–4341 (1995).

    ADS  Article  Google Scholar 

  18. Barreiro, J. T., Langford, N. K., Peter, N. A. & Kwiat, P. G. Generation of hyperentangled photon pairs. Phys. Rev. Lett. 95, 260501 (2005).

    ADS  Article  Google Scholar 

  19. Gao, W.-B., et al. Experimental demonstration of a hyper-entangled ten-qubit Schrödinger cat state. Nature Phys. 6, 331–335 (2010).

    ADS  Article  Google Scholar 

  20. 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).

    ADS  Article  Google Scholar 

  21. Lanyon, B. P. et al. Towards quantum chemistry on a quantum computer. Nature Chem. 2, 106–111 (2010).

    ADS  Article  Google Scholar 

  22. Ma, X.-S., Dakic, B., Naylor, W., Zeilinger, A. & Walther, P. Quantum simulation of the wavefunction to probe frustrated Heisenberg spin systems. Nature Phys. 7, 399–405 (2011).

    ADS  Article  Google Scholar 

  23. Raussendorf, R., Harrington, J. & Goyal, K. Topological fault-tolerance in cluster state quantum computation. New J. Phys. 9, 199 (2007).

    ADS  MathSciNet  Article  Google Scholar 

  24. Barreiro, J. T. et al. Experimental multiparticle entanglement dynamics induced by decoherence. Nature Phys. 6, 943–946 (2010).

    ADS  Article  Google Scholar 

  25. Greenberger, D. M., Horne, M., Shimony, A. & Zeilinger, A. Bell's theorem without inequalities. Am. J. Phys. 58, 1131–1143 (1990).

    ADS  MathSciNet  Article  Google Scholar 

  26. Barbieri, M. et al. Parametric down conversion and optical quantum gates: two's company, four's a crowd. J. Mod. Opt. 56, 209–214 (2009).

    ADS  Article  Google Scholar 

  27. Weinhold, T. J. et al. Understanding photonic quantum-logic gates: the road to fault tolerance. Preprint at http://arXiv.org/abs/0808.0794 (2008).

  28. Keller, T. E. & Rubin, M. H. Theory of two-photon entanglement for spontaneous parametric down-conversion driven by a narrow pump pulse. Phys. Rev. A 56, 1534–1541 (1997).

    ADS  Article  Google Scholar 

  29. Grice, W. P. & Walmsley, I. A. Spectral information and distinguishability in type-II down-conversion with a broadband pump. Phys. Rev. A 56, 1627–1634 (1997).

    ADS  Article  Google Scholar 

  30. Mosley, P. J. et al. Heralded generation of ultrafast single photons in pure quantum states. Phys. Rev. Lett. 100, 133601 (2008).

    ADS  Article  Google Scholar 

  31. Hein, M., Eisert, J. & Briegel, H. J. Multiparty entanglement in graph states. Phys. Rev. A 69, 062311 (2004).

    ADS  MathSciNet  Article  Google Scholar 

  32. Bouwmeester, D. et al. Experimental quantum teleportation. Nature 390, 575–579 (1997).

    ADS  Article  Google Scholar 

  33. Bourennane, M. et al. Experimental detection of multipartite entanglement using witness operators. Phys. Rev. Lett. 92, 087902 (2004).

    ADS  Article  Google Scholar 

Download references

Acknowledgements

The authors thank M. Cramer for useful discussions. This work was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences and the National Fundamental Research Program (grant no. 2011CB921300).

Author information

Authors and Affiliations

Authors

Contributions

X.-C.Y., X.-H.B., Y.-A.C. and J.-W.P. conceived and designed the research. X.-C.Y., T.-X.W., P.X., H.L., G.-S.P. and C.-Z.P. carried out the experiment. X.-H.B. programmed the FPGA logic. C.-Y.L. contributed theoretical analysis tools. X.-C.Y. and Y.-A.C. analysed the data. X.-C.Y., C.-Y.L., Y.-A.C. and J.-W.P. wrote the manuscript. C.-Y.L., Y.-A.C. and J.-W.P. supervised the project.

Corresponding authors

Correspondence to Chao-Yang Lu or Jian-Wei Pan.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 229 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Yao, XC., Wang, TX., Xu, P. et al. Observation of eight-photon entanglement. Nature Photon 6, 225–228 (2012). https://doi.org/10.1038/nphoton.2011.354

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphoton.2011.354

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing