Letter | Published:

Entanglement of single-photons and chiral phonons in atomically thin WSe2

Nature Physicsvolume 15pages221227 (2019) | Download Citation

Abstract

Quantum entanglement is a fundamental phenomenon that, on the one hand, reveals deep connections between quantum mechanics, gravity and spacetime1,2, and on the other hand, has practical applications as a key resource in quantum information processing3. Although it is routinely achieved in photon–atom ensembles4, entanglement involving solid-state5,6,7 or macroscopic objects8 remains challenging albeit promising for both fundamental physics and technological applications. Here, we report entanglement between collective, chiral vibrations in a two-dimensional WSe2 host—chiral phonons (CPs)—and single-photons emitted from quantum dots9,10,11,12,13 (QDs) present in it. CPs that carry angular momentum were recently observed in WSe2 and are a distinguishing feature of the underlying honeycomb lattice14,15. The entanglement results from a ‘which-way’ scattering process, involving an optical excitation in a QD and doubly-degenerate CPs, which takes place via two indistinguishable paths. Our unveiling of entanglement involving a macroscopic, collective excitation together with strong interactions between CPs and QDs in two-dimensional materials opens up ways for phonon-driven entanglement of QDs and engineering chiral or non-reciprocal interactions at the single-photon level.

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Acknowledgements

We acknowledge many enlightening discussions with A. Imamoğlu, W. Gao and M. Kroner. We also acknowledge technical help from T. Neal and E. Liu. A.S. acknowledges support from Emory University startup funds and the National Science Foundation through the EFRI Program grant number EFMA-1741691. L.Z. thanks M. Gao for helpful calculations and discussions, and acknowledges support from the National Natural Science Foundation of China (grant No. 11574154). Q.X. gratefully acknowledges strong support from the Singapore National Research Foundation via an NRF-ANR joint grant (NRF2017-NRF-ANR002 2D-Chiral) and the Singapore Ministry of Education via an AcRF Tier2 grant (MOE2017-T2-1-040) and Tier1 grants (RG 113/16 and RG 194/17)

Author information

Author notes

  1. These authors contributed equally. Xiaotong Chen, Xin Lu, Sudipta Dubey.

Affiliations

  1. Department of Physics, Emory University, Atlanta, GA, USA

    • Xiaotong Chen
    • , Xin Lu
    • , Sudipta Dubey
    • , Qiang Yao
    •  & Ajit Srivastava
  2. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore

    • Sheng Liu
    • , Xingzhi Wang
    •  & Qihua Xiong
  3. NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore

    • Qihua Xiong
  4. Center for Quantum Transport and Thermal Energy Science, School of Physics and Technology, Nanjing Normal University, Nanjing, China

    • Lifa Zhang

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Contributions

X.C., X.L., S.D. and Q.Y. carried out the quantum dot measurements and S.L. measured the Raman data. X.L. and X.W. prepared the samples. A.S., L.Z. and Q.X. supervised the project. All authors were involved in analysis of the experimental data and contributed extensively to this work.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Ajit Srivastava.

Supplementary information

  1. Supplementary information

    Supplementary Text, Figure 1–13 and Supplementary References

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https://doi.org/10.1038/s41567-018-0366-7