The emission of Hawking radiation from a black hole was predicted to be stationary, which is necessary for the correspondence between Hawking radiation and blackbody radiation. Spontaneous Hawking radiation was observed in analogue black holes in atomic Bose–Einstein condensates, although the stationarity was not probed. Here we confirm that the spontaneous Hawking radiation is stationary by observing such a system at six different times. Furthermore, we follow the time evolution of Hawking radiation and compare and contrast it with predictions for real black holes. We observe the ramp-up of Hawking radiation followed by stationary spontaneous emission, similar to a real black hole. The end of the spontaneous Hawking radiation is marked by the formation of an inner horizon, which is seen to cause stimulated Hawking radiation, as predicted. We find that the stimulated Hawking and partner particles are directly observable, and that the stimulated emission evolves from multi-mode to monochromatic. Numerical simulations suggest that Bogoliubov–Cherenkov–Landau stimulation predominates, rather than black-hole lasing.

据预测，黑洞的霍金辐射是静止的，这对于霍金辐射和黑体辐射之间的对应关系是必要的。在原子玻色-爱因斯坦凝聚体的模拟黑洞中观察到自发的霍金辐射，尽管没有探测到平稳性。在这里，我们通过在六个不同时间观察这样的系统来确认自发霍金辐射是静止的。此外，我们跟踪霍金辐射的时间演化，并将其与对真实黑洞的预测进行比较和对比。我们观察到霍金辐射的上升，然后是静止的自发辐射，类似于真正的黑洞。自发霍金辐射结束的标志是内部视界的形成，正如预测的那样，这被认为会引起受激霍金辐射。我们发现受激霍金粒子和伙伴粒子是可直接观测到的，受激发射从多模演变为单色。数值模拟表明，Bogoliubov-Cherenkov-Landau 刺激占主导地位，而不是黑洞激光。