Quantum fluctuations in a continuous vectorial Kerr medium model - art. no. 063801

We consider a model for a Kerr medium in a planar resonator, which takes in to account the vectorial character of the radiation field. We analyze the s patial behavior of quantum fluctuations around a steady state, with a roll- pattern configuration in the beam cross section, using a Langevin treatment based on the Wigner representation. The spatial distribution of the quantu m fluctuations around the roll pattern is dominated by the neutral (or Gold stone) mode, corresponding to rigid spatial displacements of the pattern. T he spatial configuration of the field immediately outside the cavity input- output mirror depends on the time window over which fluctuations are averag ed: only when the time window is on the order of the cavity lifetime the ou tput field fluctuations are qualitatively similar to that of the intracavit y field. The quantum correlations among the fields in play, as described by the full multimode model, turn out to be in good agreement with those pred icted by a simple three-mode model.