We investigate the quantum properties for the codirectional three-mode Kerr
nonlinear coupler. We investigate single-, two- and three-mode quadrature
squeezing, Wigner function and purity. We prove that this device can provide
richer nonclassical effects than those produced by the conventional coupler,
i.e. the two-mode Kerr coupler. We show that it can provide squeezing and the
quadrature squeezing exhibiting leaf-revival-collapse phenomenon in dependence
on the values of the interaction parameters. In contrast to the conventional
Kerr coupler two different forms of cat states can be simultaneously generated
in the waveguides. We deduce conditions required for the complete
disentanglement between the components of the system.Comment: 23 pages, 6 figure