  We study the effect of noise-induced dephasing on collisional phase-diffusion
in the two-site Bose-Hubbard model. Dephasing of the quasi-momentum modes may
slow down phase-diffusion in the quantum Zeno limit. Remarkably, the degree of
suppression is enhanced by a bosonic factor of order $N/\log{N}$ as the
particle number $N$ increases.

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