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Heralded entanglement between solid-state qubits separated by three metres

Nature volume 497, pages 86–90 (2013)Cite this article

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Abstract

Quantum entanglement between spatially separated objects is one of the most intriguing phenomena in physics. The outcomes of independent measurements on entangled objects show correlations that cannot be explained by classical physics. As well as being of fundamental interest, entanglement is a unique resource for quantum information processing and communication. Entangled quantum bits (qubits) can be used to share private information or implement quantum logical gates1,2. Such capabilities are particularly useful when the entangled qubits are spatially separated3,4,5, providing the opportunity to create highly connected quantum networks6 or extend quantum cryptography to long distances7,8. Here we report entanglement of two electron spin qubits in diamond with a spatial separation of three metres. We establish this entanglement using a robust protocol based on creation of spin–photon entanglement at each location and a subsequent joint measurement of the photons. Detection of the photons heralds the projection of the spin qubits onto an entangled state. We verify the resulting non-local quantum correlations by performing single-shot readout9 on the qubits in different bases. The long-distance entanglement reported here can be combined with recently achieved initialization, readout and entanglement operations9,10,11,12,13 on local long-lived nuclear spin registers, paving the way for deterministic long-distance teleportation, quantum repeaters and extended quantum networks.

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Figure 1: Experimental set-up and protocol for generating long-distance entanglement between two solid-state spin qubits.
Figure 2: Generating and detecting indistinguishable photons.
Figure 3: Verification of entanglement using spin–spin correlations.
Figure 4: Dependence of the fidelity and the number of entanglement events on the detection time difference of the photons.

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Acknowledgements

We thank F. Jelezko, P. Kok, M. Lukin, J. Morton, E. Togan and L. Vandersypen for discussions and comments, and R. N. Schouten and M. J. Tiggelman for technical assistance. We acknowledge support from the Dutch Organization for Fundamental Research on Matter (FOM), the Netherlands Organization for Scientific Research (NWO), the DARPA QuASAR programme, the EU SOLID, DIAMANT and S3NANO programmes and the European Research Council through a Starting Grant.

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Authors and Affiliations

  1. Kavli Institute of Nanoscience Delft, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands,

    H. Bernien, B. Hensen, W. Pfaff, G. Koolstra, M. S. Blok, L. Robledo, T. H. Taminiau & R. Hanson

  2. Element Six Ltd, Kings Ride Park, Ascot, SL5 8BP, Berkshire, UK

    M. Markham & D. J. Twitchen

  3. McGill University Department of Physics, 3600 Rue University, Montreal, H3A 2T8, Quebec, Canada

    L. Childress

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Contributions

H.B., B.H., L.R, L.C. and R.H. designed the experiment. H.B., B.H., W.P., G.K. and M.S.B. performed the experiments. H.B., B.H., W.P., G.K., M.S.B., T.H.T. and R.H. analysed the results. H.B., M.M. and D.J.T. fabricated the devices. H.B., B.H., W.P., M.S.B., L.C. and R.H. wrote the manuscript. All authors discussed the results and commented on the manuscript.

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Correspondence to R. Hanson.

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The authors declare no competing financial interests.

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Bernien, H., Hensen, B., Pfaff, W. et al. Heralded entanglement between solid-state qubits separated by three metres. Nature 497, 86–90 (2013). https://doi.org/10.1038/nature12016

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