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Device-independent quantum random-number generation

Nature volume 562, pages 548–551 (2018)Cite this article

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Abstract

Randomness is important for many information processing applications, including numerical modelling and cryptography1,2. Device-independent quantum random-number generation (DIQRNG)3,4 based on the loophole-free violation of a Bell inequality produces genuine, unpredictable randomness without requiring any assumptions about the inner workings of the devices, and is therefore an ultimate goal in the field of quantum information science5,6,7. Previously reported experimental demonstrations of DIQRNG8,9 were not provably secure against the most general adversaries or did not close the ‘locality’ loophole of the Bell test. Here we present DIQRNG that is secure against quantum and classical adversaries10,11,12. We use state-of-the-art quantum optical technology to create, modulate and detect entangled photon pairs, achieving an efficiency of more than 78 per cent from creation to detection at a distance of about 200 metres that greatly exceeds the threshold for closing the ‘detection’ loophole of the Bell test. By independently and randomly choosing the base settings for measuring the entangled photon pairs and by ensuring space-like separation between the measurement events, we also satisfy the no-signalling condition and close the ‘locality’ loophole of the Bell test, thus enabling the realization of the loophole-free violation of a Bell inequality. This, along with a high-voltage, high-repetition-rate Pockels cell modulation set-up, allows us to accumulate sufficient data in the experimental time to extract genuine quantum randomness that is secure against the most general adversaries. By applying a large (137.90 gigabits × 62.469 megabits) Toeplitz-matrix hashing technique, we obtain 6.2469 × 107 quantum-certified random bits in 96 hours with a total failure probability (of producing a random number that is not guaranteed to be perfectly secure) of less than 10−5. Our demonstration is a crucial step towards transforming DIQRNG from a concept to a key aspect of practical applications that require high levels of security and thus genuine randomness7. Our work may also help to improve our understanding of the origin of randomness from a fundamental perspective.

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Fig. 1: Schematics of the experiment.
Fig. 2: Space–time diagram for the experimental design.
Fig. 3: Randomness generation versus number of trials.

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Data availability

The data that support the findings of this study are available from the corresponding authors on reasonable request. Source Data for Fig. 3 is provided with the online version of the paper.

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Acknowledgements

We thank S.-R. Zhao, Y.-H. Li, L.-K. Chen and R. Jin for experimental assistance, J. Zhong and S.-C. Shi for low-temperature system maintenance, and T. Peng, Y. Cao, C.-Z. Peng and Y.-A. Chen for discussions. This work was supported by the National Key R&D Program of China (2017YFA0303900, 2017YFA0304000), the National Natural Science Foundation of China, the Chinese Academy of Sciences and the Anhui Initiative in Quantum Information Technologies.

Reviewer information

Nature thanks R. Colbeck and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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Authors and Affiliations

  1. National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, China

    Yang Liu, Ming-Han Li, Jian-Yu Guan, Bing Bai, Wen-Zhao Liu, Cheng Wu, Xiao Yuan, Jun Zhang, Jingyun Fan, Qiang Zhang & Jian-Wei Pan

  2. Shanghai Branch, CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai, China

    Yang Liu, Ming-Han Li, Jian-Yu Guan, Bing Bai, Wen-Zhao Liu, Cheng Wu, Xiao Yuan, Jun Zhang, Jingyun Fan, Qiang Zhang & Jian-Wei Pan

  3. Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China

    Qi Zhao, Xiao Yuan & Xiongfeng Ma

  4. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China

    Weijun Zhang, Hao Li, Zhen Wang & Lixing You

  5. NTT Basic Research Laboratories and NTT Research Center for Theoretical Quantum Physics, NTT Corporation, Atsugi, Japan

    Yanbao Zhang & W. J. Munro

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  1. Yang Liu
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Contributions

X.M., J.F., Q.Z. and J.-W.P. conceived the research. Y.L., X.M., J. F., Q.Z. and J.-W.P. designed the experiment. Y.L., M.-H.L. and C.W. designed and implemented the source of entangled photon pairs. W.-Z.L. and J.-Y.G. designed the data acquisition software. W.Z., H.L., Z.W. and L.Y. fabricated and characterized the superconducting nanowire single-photon detector. B.B. and J.Z. designed the quantum random-number generators for the measurement setting choices. Q. Zhao, X.Y. and X.M. performed the protocol analysis, numerical modelling and randomness extraction. Y.Z. and W.J.M. performed the hypothesis tests. All authors contributed to the experimental realization, data analysis and manuscript preparation. J.-W.P. supervised the project.

Corresponding authors

Correspondence to Xiongfeng Ma, Jingyun Fan, Qiang Zhang or Jian-Wei Pan.

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Supplementary information

Supplementary Information

This file contains Supplementary Text, Supplementary Figures 1-6, and Supplementary Tables 1-7. The Supplementary Information describes the theory of DIQRNG (Section I), the experimental details (Section II), and the experimental results (Section III).

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Liu, Y., Zhao, Q., Li, MH. et al. Device-independent quantum random-number generation. Nature 562, 548–551 (2018). https://doi.org/10.1038/s41586-018-0559-3

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