Letter | Published:

Generation of heralded entanglement between distant hole spins

Nature Physics volume 12, pages 218223 (2016) | Download Citation

Abstract

Quantum entanglement emerges naturally in interacting quantum systems and plays a central role in quantum information processing1,2,3,4. But the generation of entanglement does not require direct interactions: single-photon detection in spin-flip Raman scattering projects two distant spins onto a maximally entangled state, provided that it is impossible to determine the source of the detected photon5. Here, we demonstrate such heralded quantum entanglement6,7,8,9 of two quantum-dot hole spins separated by 5 m using single-photon interference. Thanks to fast spin initialization in 10 ns, hole-spin coherence lasting 40 ns and efficient photon extraction from dots10,11,12 embedded in leaky microcavity structures, we generate 2,300 entangled spin pairs per second, which represents a 1,000-fold improvement as compared to previous experiments13. The delayed two-photon interference scheme we developed allows the efficient verification of quantum correlations. Combined with schemes for transferring quantum information to a long-lived memory qubit14, fast entanglement generation could impact quantum repeater architectures.

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Acknowledgements

The Authors acknowledge many useful discussions with M. Kroner. This work is supported by NCCR Quantum Photonics (NCCR QP), the research instrument of the Swiss National Science Foundation (SNSF), and by the Swiss NSF under Grant No. 200020-159196.

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Author notes

    • Aymeric Delteil
    • , Zhe Sun
    •  & Wei-bo Gao

    These authors contributed equally to this work.

Affiliations

  1. Institute of Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland

    • Aymeric Delteil
    • , Zhe Sun
    • , Wei-bo Gao
    • , Emre Togan
    • , Stefan Faelt
    •  & Ataç Imamoğlu
  2. Div. of Physics and Applied Physics, Nanyang Tech. Univ., Singapore 637371, Singapore

    • Wei-bo Gao

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Contributions

All authors contributed extensively to this work.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Ataç Imamoğlu.

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DOI

https://doi.org/10.1038/nphys3605

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