Light at the Horizon: Observation of Stimulated Hawking Radiation in Optics

Hawking radiation has been one of the intellectually most influential predictions of theoretical physics, connecting general relativity with quantum mechanics and thermodynamics, but it has never been fully observed yet, even in laboratory analogues, despite admirable experimental progress made. Here we report on clear, non-ambiguous measurements of stimulated Hawking radiation in nonlinear fiber optics. Our experiment shows the surprising robustness of the Hawking effect in optics and may finally clear the path towards a full quantum demonstration.