  The full set of resonant states in double and triple quantum well/barrier
structures is investigated. This includes bound, anti-bound and normal resonant
states which are all eigensolutions of Schrodinger's equation with generalized
outgoing wave boundary conditions. The transformation of resonant states and
their transitions between different subgroups as well as the role of each
subgroup in observables, such as the quantum transmission, is analyzed. The
quantum well potentials are modeled by Dirac delta functions; therefore, as
part of this study, the well-known problem of bound states in delta-like
potentials is also revisited.
