We discuss collision-induced spontaneous decay in a system of cold atoms and caloric effect manifesting in the heating of the atomic system during spontaneous decay. It is shown that the caloric effect is caused by inelastic atom–atom collisions accompanied by the spontaneous emission of photons. Because of the imbalance between the rate of emission of the photons with the frequency higher and lower than the atomic transition frequency, the atomic system, under some conditions, is heated up. The value of the critical temperature is found, which separates the regions where the collision-induced spontaneous decay is exothermic and endothermic.
Spontaneous emission of atomic systems in the presence of incident fields