it gives rise to the phase transition in the form of *spontaneous symmetry breaking* (SSB) of the GS [@book]. In its simplest manifestation, which is provided by the DWP, the SSB implies that one well traps a larger atomic density or field power than the other. This effect also implies the breakup of the basic principle of quantum mechanics, according to which the GS cannot be degenerate, as the SSB gives rise to a pair of two mutually symmetric GSs in the DWP, with the maximum of the wave function found in either potential well (as mentioned above, the Jahn-Teller effect gives rise to a qualitatively similar situation). The same DWP setting admits a symmetric state coexisting with the asymmetric ones, but, above the SSB point, the symmetric wave function no longer represents the GS, being unstable against symmetry-breaking perturbations. In the course of the spontaneous transition from the unstable symmetric state to a stable asymmetric one, the choice between the two mutually degenerate asymmetric states is determined by random perturbations, which push the system to build the maximum of the wave function in the left or right potential well. The SSB is a ubiquitous phenomenon, with well-known manifestations in 