We study the tunneling dynamics in a time-periodically modulated two-mode
Bose-Hubbard model using Floquet theory. We consider situations where the
system is in the self-trapping regime and either the tunneling amplitude, the
interaction strength, or the energy difference between the modes is modulated.
In the former two cases, the tunneling is enhanced in a wide range of
modulation frequencies, while in the latter case the resonance is narrow. We
explain this difference with the help of Floquet analysis. If the modulation
amplitude is weak, the locations of the resonances can be found using the
spectrum of the non-modulated Hamiltonian. Furthermore, we use Floquet analysis
to explain the coherent destruction of tunneling (CDT) occurring in a
large-amplitude modulated system. Finally, we present two ways to create a NOON
state (a superposition of N particles in mode 1 with zero particles in mode 2
and vice versa). One is based on a coherent oscillation caused by detuning from
a partial CDT. The other makes use of an adiabatic variation of the modulation
frequency. This results in a Landau-Zener type of transition between the ground
state and a NOON-like state.Comment: 16 pages, 11 figures; published in Phys. Rev.