  This paper deals with the broad class of magnetic systems having a single or
collective spin $S$ with an energy barrier, such as Rare-Earth elements and
their compounds, Single Molecule Magnets with uniaxial anisotropy and more
generally any other quantum system made of single or multiple objects with
discrete energy levels. Till now, the reversal of the magnetization of such
systems at zero Kelvin required to make use of quantum tunneling with a
significant transverse field or transverse anisotropy term, at resonance. Here,
we show that another very simple method exists. It simply consists in the
application of a particular sequence of electromagnetic radiations in the
ranges of optical or microwave frequencies, depending on the characteristics of
the system (spin and anisotropy values for magnetic systems). This produces
oscillations of the Rabi type that pass above the barrier, thus extending these
oscillations between the two energy wells. with mixtures of all the 2S+1
states. In addition to its basic character, this approach opens up new
directions of research in quantum information with possible breakthroughs in
the current use of multiple quantum bits.
