On the Occurrence of a Phase Transition in Atomic Systems

Abstract: We present a simple argument confirming the spontaneous quantum condensation of an electromagnetic field in matter in the case of a multi-level atomic system coupled to a single-mode electromagnetic field in the dipole approximation. The obtained result disproves the validity of a ``no-go theorem'' and fully rehabilitates theories of spontaneous quantum condensation of the electromagnetic field in matter. Peculiar features of the identified coherent states are outlined.