  We investigate a notable class of states peculiar to a bosonic binary mixture
featuring repulsive intraspecies and attractive interspecies couplings. We
evidence that, for small values of the hopping amplitudes, one can access
particular regimes marked by the fact that the interwell boson transfer occurs
in a jerky fashion. This property is shown to be responsible for the emergence
of a staircase-like structure in the phase diagram of a mixture confined in a
ring trimer and to strongly resemble the mechanism of the superfluid-Mott
insulator transition. Under certain conditions, in fact, we show that it is
possible to interpret the interspecies attraction as an effective chemical
potential and the supermixed soliton as an effective particle reservoir. Our
investigation is developed both within a fully quantum approach based on the
analysis of several quantum indicators and by means of a simple analytical
approximation scheme capable of capturing the essential features of this
ultraquantum effect.
