Abstract
Hawking radiation1—the emission of quantum particles at the event horizon of a black hole2—connects gravity with quantum mechanics and thermodynamics3,4,5. But Hawking radiation has never been observed in astronomy, only in laboratory analogues6,7,8,9, and the chances of ever observing it in space are astronomically small9. The energy of Hawking radiation must come from the gravitational field around the black hole2, but how field quanta generate Hawking quanta has been unknown. Here we report on experimental and theoretical evidence for the process that generates Hawking radiation in a fibre-optical analogue of the event horizon10,11. There, as in gravity2, it has been believed that Hawking radiation comes from a complicated, cascaded process12; here we have identified theoretically a simple, direct process and observed experimentally how this process reacts back onto the field. Our findings suggest an equally direct process for other laboratory analogues6,7,8,13,14,15,16,17 and perhaps also for gravitational fields, shedding light on how black holes might radiate.
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Acknowledgements
We are grateful to S. Amiranashvili, U. Bandelow, H. Cohen, J. Drori, M. Gelvan, F. König, Y. Rosenberg, S. Rotter and, most of all, the late Y. Silberberg for help, advice and scientific discussions.
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The authors declare no competing interests.
Funding
L.M.P. and U.L. were supported by the Israel Science Foundation, the Murray B. Koffler Professorial Chair and U.L. by a Global Fellowship of the Vienna Institute of Technology. R.A.-S. and D.B. acknowledge the support of Conahcyt (Mexico) Ciencia de Frontera 51458-2019 and the Marcos Moshinsky Chair (2023).
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L.M.P. conducted, analysed and led the experiment. R.A.-S. and D.B. performed numerical simulations. U.L. developed the analytical theory. D.B. and U.L. carried out the data analysis, supervised the project and conceived the idea of this paper.
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Nature thanks Francesco Marino, Baocheng Zhang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
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Procopio, L.M., Aguero-Santacruz, R., Bermudez, D. et al. Backreaction of stimulated Hawking radiation in an optical analogue. Nature (2026). https://doi.org/10.1038/s41586-026-10720-3
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DOI: https://doi.org/10.1038/s41586-026-10720-3