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Traceable random numbers from a non-local quantum advantage

Nature volume 642, pages 916–921 (2025)Cite this article

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Abstract

The unpredictability of random numbers is fundamental to both digital security1,2 and applications that fairly distribute resources3,4. However, existing random number generators have limitations—the generation processes cannot be fully traced, audited and certified to be unpredictable. The algorithmic steps used in pseudorandom number generators5 are auditable, but they cannot guarantee that their outputs were a priori unpredictable given knowledge of the initial seed. Device-independent quantum random number generators6,7,8,9 can ensure that the source of randomness was unknown beforehand, but the steps used to extract the randomness are vulnerable to tampering. Here we demonstrate a fully traceable random number generation protocol based on device-independent techniques. Our protocol extracts randomness from unpredictable non-local quantum correlations, and uses distributed intertwined hash chains to cryptographically trace and verify the extraction process. This protocol forms the basis for a public traceable and certifiable quantum randomness beacon that we have launched10. Over the first 40 days of operation, we completed the protocol 7,434 out of 7,454 attempts—a success rate of 99.7%. Each time the protocol succeeded, the beacon emitted a pulse of 512 bits of traceable randomness. The bits are certified to be uniform with error multiplied by actual success probability bounded by 2−64. The generation of certifiable and traceable randomness represents a public service that operates with an entanglement-derived advantage over comparable classical approaches.

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Fig. 1: Overview of hash chain protocol.
Fig. 2: Experimental set-up.
Fig. 3: Protocol latency.
Fig. 4: Running entropy analysis.

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Data availability

All data and information used to generate each randomness pulse are publicly available at https://random.colorado.edu. Additional data used for diagnostic plots shown in the Supplementary Information are available by request from the corresponding authors. Source data are provided with this paper.

Code availability

The code used to run the beacon, analyse the data, and verify or trace the randomness in a pulse is publicly available via GitHub at https://github.com/buff-beacon-project. Code used to generate the figures is available by request from the corresponding authors.

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Acknowledgements

This work includes contributions of the NIST, which are not subject to US copyright. The use of trade names does not imply endorsement by the US Government. The work is supported by the National Science Foundation RAISE-TAQS programme (award 1840223), the CU through the ‘QuEST Seed Award: A Quantum Randomness Beacon’, the Colorado Office of Economic Impact (award number DO 2023-0335), in part by the European Union ‘NextGenerationEU/PRTR’. Spanish Ministry of Science MCIN: project SAPONARIA (PID2021-123813NB-I00) and ‘Severo Ochoa’ Center of Excellence CEX2019-000910-S. Generalitat de Catalunya through the CERCA programme and grant number 2021 SGR 01453; Fundació Privada Cellex; Fundació Mir-Puig. This work was performed in part at Oak Ridge National Laboratory, operated by UT-Battelle for the US Department of Energy under contract number DE-AC05-00OR22725. We thank S. Glancy, B. Chen, L. Norton, E. Some and R. Snyder for discussions regarding the project, and J. G. Price for providing the image used in Fig. 2.

Author information

Author notes

  1. Joseph M. Cavanagh

    Present address: Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, CA, USA

Authors and Affiliations

  1. Department of Physics, University of Colorado, Boulder, CO, USA

    Gautam A. Kavuri, Jasper Palfree, Dileep V. Reddy, Michael D. Mazurek, Paul D. Beale, Sae Woo Nam, Emanuel Knill & Lynden K. Shalm

  2. Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO, USA

    Gautam A. Kavuri, Jasper Palfree, Dileep V. Reddy, Michael D. Mazurek, Joseph M. Cavanagh, Aagam Dalal, Sae Woo Nam, Richard P. Mirin, Martin J. Stevens & Lynden K. Shalm

  3. Quantum Information Science Section, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

    Yanbao Zhang

  4. Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, Gaithersburg, MD, USA

    Joshua C. Bienfang

  5. Center for Quantum Information and Control, University of New Mexico, Albuquerque, NM, USA

    Mohammad A. Alhejji

  6. Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO, USA

    Aliza U. Siddiqui

  7. Quside Technologies, Barcelona, Spain

    Carlos Abellán & Waldimar Amaya

  8. ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain

    Morgan W. Mitchell

  9. ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain

    Morgan W. Mitchell

  10. Department of Mathematics, University of Colorado, Boulder, CO, USA

    Katherine E. Stange

  11. Strativia (NIST Cryptographic Technology Group), Gaithersburg, MD, USA

    Luís T. A. N. Brandão

  12. Information Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA

    Harold Booth & René Peralta

  13. Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA

    Emanuel Knill

  14. Applied and Computational Mathematics Division, National Institute of Standards and Technology, Boulder, CO, USA

    Emanuel Knill

  15. Quantum Engineering Initiative, Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO, USA

    Lynden K. Shalm

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Contributions

G.A.K. built and performed the experiment with assistance from L.K.S., M.D.M. and M.J.S., and collected and analysed data. J.P. and L.K.S. developed the Twine protocol with inputs from L.T.A.N.B., H.B. and R.P., and implemented it with assistance from J.M.C. and A.D. D.V.R. provided the high-efficiency detectors. Y.Z., M.A.A., A.U.S., L.K.S., G.A.K. and E.K. participated in the data analysis. J.C.B. provided electronics and hardware RNGs. C.A., W.A. and M.W.M. provided hardware RNGs. P.D.B. and J.P. developed a software RNG used in CURBy. J.P., K.E.S., L.K.S. and P.D.B. developed the hardware and software at CU to run the CURBy network. L.K.S., S.W.N. and R.P.M. supervised the project. G.A.K. led the writing of the manuscript with all authors contributing.

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Correspondence to Gautam A. Kavuri or Lynden K. Shalm.

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Kavuri, G.A., Palfree, J., Reddy, D.V. et al. Traceable random numbers from a non-local quantum advantage. Nature 642, 916–921 (2025). https://doi.org/10.1038/s41586-025-09054-3

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