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Topologically protected quantum entanglement emitters

Nature Photonics volume 16, pages 248–257 (2022)Cite this article

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Abstract

Entanglement and topology portray nature at the fundamental level but differently. Entangled states of particles are intrinsically sensitive to the environment, whereas the topological phases of matter are naturally robust against environmental perturbations. Harnessing topology to protect entanglement has great potential for reliable quantum applications. Generating topologically protected entanglement, however, remains a significant challenge, requiring the operation of complex quantum devices in extreme conditions. Here we report topologically protected entanglement emitters that emit a topological Einstein–Podolsky–Rosen state and a multiphoton entangled state from a monolithically integrated plug-and-play silicon photonic chip in ambient conditions. The device emulating a photonic anomalous Floquet insulator allows the generation of four-photon topological entangled states at non-trivial edge modes, verified by the observation of a reduced de Broglie wavelength. Remarkably, we show that the Einstein–Podolsky–Rosen entanglement can be topologically protected against artificial structure defects by comparing the state fidelities of 0.968 ± 0.004 and 0.951 ± 0.010 for perfect and defected emitters, respectively. Our topologically protected devices may find applications in quantum computation and in the study of quantum topological physics.

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Fig. 1: A topological quantum entanglement emitter in a photonic anomalous Floquet topological insulator.
Fig. 2: Characterizations of the topological quantum device.
Fig. 3: Experimental demonstration of topological entanglement.
Fig. 4: Demonstration of topological protection of quantum entanglement against certain imperfections.

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Data availability

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

Code availability

The analysis codes are available from the corresponding authors upon reasonable request.

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Acknowledgements

We thank H. Xu, Q. He and P. Xue for useful discussions. We acknowledge support from the National Natural Science Foundation of China (nos. 61975001, 61590933, 61904196, 61675007, 92150302, 11734001, 91950204, 11527901, 62171406, 61801426 and 11961141010), the National Key R&D Program of China (nos. 2019YFA0308702, 2018YFB1107205, 2018YFB2200403 and 2018YFA0704404), Beijing Natural Science Foundation (Z190005), Beijing Municipal Science and Technology Commission (Z191100007219001) and Key R&D Program of Guangdong Province (2018B030329001). L.Y. acknowledges support from the Natural Science Foundation of Shanghai (19ZR1475700) and the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning. F.G. acknowledges support from the ZJNSF under grant no. Z20F010018, the National Key Laboratory Foundation (no. 6142205200402) and the Fundamental Research Funds for the Central Universities (no. 2020XZZX002-15).

Author information

Author notes

  1. These authors contributed equally: Tianxiang Dai, Yutian Ao, Jueming Bao, Jun Mao, Yulin Chi.

Authors and Affiliations

  1. State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, China

    Tianxiang Dai, Yutian Ao, Jueming Bao, Jun Mao, Yulin Chi, Zhaorong Fu, Yilong You, Xiaojiong Chen, Chonghao Zhai, Yan Li, Xiaoyong Hu, Qihuang Gong & Jianwei Wang

  2. Institute of Microelectronics, Chinese Academy of Sciences, Beijing, China

    Bo Tang, Yan Yang & Zhihua Li

  3. State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China

    Luqi Yuan

  4. Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Science and Technology Innovation Center, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China

    Fei Gao & Xiao Lin

  5. Quantum Engineering Technology Labs, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Bristol, UK

    Mark G. Thompson

  6. Department of Physics, The University of Western Australia, Perth, Western Australia, Australia

    Jeremy L. O’Brien

  7. Frontiers Science Center for Nano-optoelectronics and Collaborative Innovation Center of Quantum Matter, Peking University, Beijing, China

    Yan Li, Xiaoyong Hu, Qihuang Gong & Jianwei Wang

  8. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, China

    Yan Li, Xiaoyong Hu, Qihuang Gong & Jianwei Wang

  9. Peking University Yangtze Delta Institute of Optoelectronics, Nantong, China

    Yan Li, Xiaoyong Hu, Qihuang Gong & Jianwei Wang

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  1. Tianxiang Dai
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Contributions

J.W. conceived the project. T.D., Y.A., J.B., J.M. and Y.C. contributed equally to this work. T.D., J.B. and Z.F. implemented the experiment. J.M., Y.C., B.T., Y. Yang and Z.L. fabricated the device. T.D., Y.A., J.B. and X.C. designed the devices. Y.A. and Y. You provided the theory and simulations. T.D., Y.A., Z.F., C.Z., L.Y., F.G. and X.L. performed the theoretical analysis. M.G.T., J.L.O., Y.L., X.H., Q.G. and J.W. managed the project. T.D., Y.A. and J.W. wrote the manuscript. All the authors discussed the results and contributed to the manuscript.

Corresponding authors

Correspondence to Yan Yang, Xiaoyong Hu, Qihuang Gong or Jianwei Wang.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–9.

Supplementary Video 1

Real-time measurement of field distributions of topological pseudospin states with a continuous scan of wavelength spanning over one FSR. Both pseudospin-up and pseudospin-down states are induced.

Supplementary Video 2

Real-time measurement of field distributions of topological pseudospin states with a continuous scan of wavelength spanning over one FSR. Pseudospin-down states are induced.

Supplementary Video 3

Real-time measurement of field distributions of topological pseudospin states with a continuous scan of wavelength spanning over one FSR. Pseudospin-up states are induced.

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Dai, T., Ao, Y., Bao, J. et al. Topologically protected quantum entanglement emitters. Nat. Photon. 16, 248–257 (2022). https://doi.org/10.1038/s41566-021-00944-2

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