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

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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Fig. 1: Chiral phonons and phonon–photon entanglement.
Fig. 2: QDs and their phonon replicas in monolayer WSe2.
Fig. 3: Polarization dependence of QDs and their phonon replicas in monolayer WSe2.
Fig. 4: Recovery of polarization of phonon replicas in a magnetic field.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

References

  1. 1.

    Maldacena, J. & Susskind, L. Cool horizons for entangled black holes. Fortschr. Phys. 61, 781–811 (2013).

    MathSciNet  Article  Google Scholar 

  2. 2.

    Cao, C., Carroll, S. M. & Michalakis, S. Space from Hilbert space: recovering geometry from bulk entanglement. Phys. Rev. D 95, 024031 (2017).

    ADS  MathSciNet  Article  Google Scholar 

  3. 3.

    Nielsen, M. A. & Chuang, I. L. Quantum Computation and Quantum Information: 10th Anniversary Edition (Cambridge Univ. Press, Cambridge, 2010).

  4. 4.

    Moehring, D. L. et al. Entanglement of single-atom quantum bits at a distance. Nature 449, 68–71 (2007).

    ADS  Article  Google Scholar 

  5. 5.

    Gao, W. B., Fallahi, P., Togan, E., Miguel-Sanchez, J. & Imamoğlu, A. Observation of entanglement between a quantum dot spin and a single photon. Nature 491, 426–430 (2012).

    ADS  Article  Google Scholar 

  6. 6.

    De Greve, K. et al. Quantum-dot spin–photon entanglement via frequency downconversion to telecom wavelength. Nature 491, 421–425 (2012).

    ADS  Article  Google Scholar 

  7. 7.

    Dolde, F. et al. Room-temperature entanglement between single defect spins in diamond. Nat. Phys. 9, 139–143 (2013).

    Article  Google Scholar 

  8. 8.

    Lee, K. C. et al. Entangling macroscopic diamonds at room temperature. Science 334, 1253–1256 (2011).

    ADS  Article  Google Scholar 

  9. 9.

    Srivastava, A. et al. Optically active quantum dots in monolayer WSe2. Nat. Nanotech. 10, 491–496 (2015).

    ADS  Article  Google Scholar 

  10. 10.

    Koperski, M. et al. Single photon emitters in exfoliated WSe2 structures. Nat. Nanotech. 10, 503–506 (2015).

    ADS  Article  Google Scholar 

  11. 11.

    Chakraborty, C., Kinnischtzke, L., Goodfellow, K. M., Beams, R. & Vamivakas, A. N. Voltage-controlled quantum light from an atomically thin semiconductor. Nat. Nanotech. 10, 507–511 (2015).

    ADS  Article  Google Scholar 

  12. 12.

    He, Y.-M. et al. Single quantum emitters in monolayer semiconductors. Nat. Nanotech. 10, 497–502 (2015).

    ADS  Article  Google Scholar 

  13. 13.

    Tonndorf, P. et al. Single-photon emission from localized excitons in an atomically thin semiconductor. Optica 2, 347–352 (2015).

    Article  Google Scholar 

  14. 14.

    Zhu, H. et al. Observation of chiral phonons. Science 359, 579–582 (2018).

    ADS  MathSciNet  Article  Google Scholar 

  15. 15.

    Zhang, L. & Niu, Q. Chiral phonons at high-symmetry points in monolayer hexagonal lattices. Phys. Rev. Lett. 115, 115502 (2015).

    ADS  Article  Google Scholar 

  16. 16.

    Xu, X., Yao, W., Xiao, D. & Heinz, T. F. Spin and pseudospins in layered transition metal dichalcogenides. Nat. Phys. 10, 343–350 (2014).

    Article  Google Scholar 

  17. 17.

    Xiao, D., Liu, G.-B., Feng, W., Xu, X. & Yao, W. Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012).

    ADS  Article  Google Scholar 

  18. 18.

    Mak, K. F., He, K., Shan, J. & Heinz, T. F. Control of valley polarization in monolayer MoS2 by optical helicity. Nat. Nanotech. 7, 494–498 (2012).

    ADS  Article  Google Scholar 

  19. 19.

    Zeng, H., Dai, J., Yao, W., Xiao, D. & Cui, X. Valley polarization in MoS2 monolayers by optical pumping. Nat. Nanotech. 7, 490–493 (2012).

    ADS  Article  Google Scholar 

  20. 20.

    Cao, T. et al. Valley-selective circular dichroism of monolayer molybdenum disulphide. Nat. Commun. 3, 887 (2012).

    Article  Google Scholar 

  21. 21.

    DiCarlo, L. et al. Preparation and measurement of three-qubit entanglement in a superconducting circuit. Nature 467, 574–578 (2010).

    ADS  Article  Google Scholar 

  22. 22.

    Steffen, M. et al. Measurement of the entanglement of two superconducting qubits via state tomography. Science 313, 1423–1425 (2006).

    ADS  MathSciNet  Article  Google Scholar 

  23. 23.

    Luo, X. et al. Effects of lower symmetry and dimensionality on Raman spectra in two-dimensional WSe2. Phys. Rev. B 88, 195313 (2013).

    ADS  Article  Google Scholar 

  24. 24.

    Kim, S., Kim, K., Lee, J.-U. & Cheong, H. Excitonic resonance effects and Davydov splitting in circularly polarized Raman spectra of few-layer WSe2. 2D Mater. 4, 045002 (2017).

    Article  Google Scholar 

  25. 25.

    Branny, A., Kumar, S., Proux, R. & Gerardot, B. D. Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor. Nat. Commun. 8, 15053 (2017).

    ADS  Article  Google Scholar 

  26. 26.

    Palacios-Berraquero, C. et al. Atomically thin quantum light-emitting diodes. Nat. Commun. 7, 12978 (2016).

    ADS  Article  Google Scholar 

  27. 27.

    Palacios-Berraquero, C. et al. Large-scale quantum-emitter arrays in atomically thin semiconductors. Nat. Commun. 8, 15093 (2017).

    ADS  Article  Google Scholar 

  28. 28.

    Gammon, D., Snow, E. S., Shanabrook, B. V., Katzer, D. S. & Park, D. Fine structure splitting in the optical spectra of single GaAs quantum dots. Phys. Rev. Lett. 76, 3005–3008 (1996).

    ADS  Article  Google Scholar 

  29. 29.

    Sidler, M. et al. Fermi polaron–polaritons in charge-tunable atomically thin semiconductors. Nat. Phys. 13, 255–261 (2016).

    Article  Google Scholar 

  30. 30.

    He, Y.-M. et al. Cascaded emission of single photons from the biexciton in monolayered WSe2. Nat. Commun. 7, 13409 (2016).

    ADS  Article  Google Scholar 

  31. 31.

    Heitz, R., Mukhametzhanov, I., Stier, O., Madhukar, A. & Bimberg, D. Enhanced polar exciton-LO-phonon interaction in quantum dots. Phys. Rev. Lett. 83, 4654–4657 (1999).

    ADS  Article  Google Scholar 

  32. 32.

    Cai, Y., Lan, J., Zhang, G. & Zhang, Y.-W. Lattice vibrational modes and phonon thermal conductivity of monolayer MoS2. Phys. Rev. B 89, 035438 (2014).

    ADS  Article  Google Scholar 

  33. 33.

    Srivastava, A. et al. Valley Zeeman effect in elementary optical excitations of monolayer WSe2. Nat. Phys. 11, 141–147 (2015).

    Article  Google Scholar 

  34. 34.

    Aivazian, G. et al. Magnetic control of valley pseudospin in monolayer WSe2. Nat. Phys. 11, 148–152 (2015).

    Article  Google Scholar 

  35. 35.

    Chen, S.-Y., Zheng, C., Fuhrer, M. S. & Yan, J. Helicity-resolved Raman scattering of MoS2, MoSe2, WS2, and WSe2 atomic layers. Nano. Lett. 15, 2526–2532 (2015).

    ADS  Article  Google Scholar 

  36. 36.

    Drapcho, S. G. et al. Apparent breakdown of Raman selection rule at valley exciton resonances in monolayer MoS2. Phys. Rev. B 95, 165417 (2017).

    ADS  Article  Google Scholar 

  37. 37.

    Yoshikawa, N., Tani, S. & Tanaka, K. Raman-like resonant secondary emission causes valley coherence in CVD-grown monolayer MoS2. Phys. Rev. B 95, 115419 (2017).

    ADS  Article  Google Scholar 

  38. 38.

    Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013).

    Article  Google Scholar 

  39. 39.

    Castellanos-Gomez, A. et al. Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping. 2D Mater. 1, 011002 (2014).

    Article  Google Scholar 

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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)

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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.

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Correspondence to Ajit Srivastava.

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Supplementary information

Supplementary Text, Figure 1–13 and Supplementary References

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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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