  For systems described by the two-site Bose-Hubbard Hamiltonian, we show that
a sinusoidal modulation of the tunneling matrix element assists higher-order
co-tunneling processes. Using this mechanism, we propose an efficient new
scheme for creating a coherent superposition of states in which all particles
are either on one site or all on the other site, the so-called NOON state. This
scheme yields an almost perfect NOON state periodically. For larger numbers of
particles, further reduction of the time to create the state is possible if
more than one modulation frequency is employed. With this scheme, NOON states
with a larger number of particles could be realized with state-of-the-art
techniques for cold Bose gases in a double-well potential.
