Lab experiment finally detects Hawking radiation from a simulated black hole

Scientists have taken a major step in proving the existence of Hawking radiation—the theoretical glow predicted to escape from black holes. A team from the University of Göttingen and the Max Planck Institute achieved this by simulating a black hole's event horizon in a lab. Their findings, published in 2023, mark the first clear experimental evidence supporting Stephen Hawking's decades-old prediction.

The researchers created an analogue black hole using a Bose-Einstein condensate (BEC) made of rubidium-87 atoms. By manipulating the flow of this ultra-cold quantum fluid, they generated a supersonic region that mimicked the event horizon of a real black hole. Within this setup, pairs of phonons—sound-wave-like quasi-particles—emerged in a way that mirrored Hawking's theoretical framework.

To detect these pairs, the team used time-of-flight expansion and high-resolution absorption imaging with CCD cameras. The measurements revealed exponentially suppressed density correlations beyond the simulated horizon, matching Hawking's predictions. Crucially, the study also observed an anti-correlation between the momenta of the emitted phonon pairs, confirming their entangled quantum nature. The experiment's success relied on isolating and amplifying the faint signals of Hawking radiation and its partner particles. Previous attempts had struggled to distinguish these correlations from background noise. Here, the researchers refined their approach by analysing the angular distribution of the emitted pairs, providing stronger evidence for the quantum origin of the effect. Beyond the BEC setup, the study included detailed simulations of polariton fluids, reinforcing the broader applicability of analogue spacetime experiments. The documented second-order correlation function further bridged the gap between theoretical models and measurable photocurrent data, offering a clearer path for future verification.

This work establishes a reliable laboratory method for studying Hawking radiation through quantum fluids. The observed correlations between phonon pairs align closely with theoretical expectations, reinforcing the quantum nature of the phenomenon. The findings open new avenues for testing fundamental physics in controlled environments, bringing us closer to a full experimental confirmation of Hawking's groundbreaking theory.