  Using effective-field theory with correlations, we investigate the effects of
interfacial pseudo-spin coupling fluctuations on the susceptibility and
polarization of ferroelectric superlattices within the framework of transverse
Ising model. It is found that the interfacial coupling fluctuations increase
the susceptibility in the low temperature region. For a strong interfacial
coupling, the phase transition temperature decreases with the strength of
fluctuations of the interfacial coupling. The dependence of the susceptibility
on the superlattice period of $BaTiO_{3}/SrTiO_{3}$ are plotted for different
interfacial coupling fluctuations strength. At room temperature, when the
interfacial coupling fluctuation increases, the peak position of the
susceptibility will shift to a large superlattice period.
