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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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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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)
The authors declare no competing interests.
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Chen, X., Lu, X., Dubey, S. et al. Entanglement of single-photons and chiral phonons in atomically thin WSe2. Nat. Phys. 15, 221–227 (2019). https://doi.org/10.1038/s41567-018-0366-7
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