In one minute

Jeff Steinhauer builds a narrow, dilute, ultracold atomic Bose-Einstein condensate with an analogue black hole horizon and an inner horizon, as in a charged black hole. He observes Hawking radiation leaving the analogue black hole, the output of a black hole laser. A standing wave grows exponentially between the horizons, from interference between the negative-energy partners of the Hawking radiation and negative-energy particles reflected from the inner horizon. The emitted Hawking radiation is clearly visible in the density-density correlation function. The lasing mode sits at about 0.3 of the Hawking temperature. The work suggests a way to probe inside black holes: strong laser-like Hawking radiation from an astrophysical black hole would reveal an inner horizon.

Observation of self-amplifying Hawking radiation in an analogue black-hole laser