Vibrating light mirrors recreate a black-hole horizon
In Santa Barbara, ultracold atoms between lasers confirm for the first time the one-way bunching predicted in modulated optical cavities.
Accelerating a mirror near light speed is impossible in the lab. Swapping light for cold atoms is notâand the result mimics an event horizon.
David Weld and colleagues at the University of California, Santa Barbara published in Physical Review Letters an experiment in which a matter-wave cavity behaves like the surroundings of a black hole (and its hypothetical opposite, a white hole). Phys.org covered it on November 6, 2026.
In a classical optical cavity, if a mirror vibrated at the lightâs round-trip rate, theory predicts waves would pile into a short pulse flowing one way, analogous to light near a horizon. That vibration would need impossible accelerations. The team cooled lithium near absolute zero, trapped it in a laser lattice so it moved below 1 m/s as a matter wave, and used two light sheets as âmirrorsâ; one oscillated about 100 times per second.
Within a few cycles the cloud concentrated into a packet on a stable path; others converged on the same one-way trajectory. Doubling the frequency made two packets; shifting the phase reversed the flow. The effect could compress optical signals and help explore photon-pair creation between accelerating mirrors.
Key facts
- Published in Physical Review Letters (Tanlimco et al., 2026); UC Santa Barbara.
- Matter-wave Fabry-PĂ©rot cavity with a light âmirrorâ driven at ~100 Hz.
- Confirms unidirectional flow analogous to black-/white-hole horizons.
- Possible route to compress optical signals without mechanical mirrors.
When the lab mimics spacetime geometry, extreme physics leaves the telescope and arrives on the optical bench.
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