  A new kind of regular quasienergy (Floquet) spectrum is found for the
generalized kicked particle under quantum-resonance conditions at generic
quasimomentum, a quantity most relevant in atom-optics experimental
realizations of kicked-rotor systems. The new non-Poisson regular spectrum has
the structure of a staggered ladder, i.e., it is the superposition of a finite
number of ladder subspectra all having the same spacing, which is independent
of the nonintegrability of the system. This spectral structure is shown to have
distinct quantum-dynamical manifestations: A suppression of quantum resonances
and a novel type of dynamical localization characterized by unique features
such as traveling-wave components in the time evolution. These phenomena are
found to be robust under small variations of the quasimomentum and should
therefore be experimentally observable using Bose-Einstein condensates with
sufficiently small quasimomentum width.
