Nonclassical tripartite field with macroscopic intensity

We realize two interlinked nonlinear interactions by injecting two intense pumps in a single nonlinear crystal. Starting from the vacuum state, the process yields a tripartite entangled state. We investigate the evolution of the mean number of photons in the three generated fields as a function of the pump-field intensities and obtain a good agreement with the predictions of a single-mode theoretical description.