  We have numerically solved the Heisenberg-Langevin equations describing the
propagation of quantized fields through an optically thick sample of atoms. Two
orthogonal polarization components are considered for the field and the
complete Zeeman sublevel structure of the atomic transition is taken into
account. Quantum fluctuations of atomic operators are included through
appropriate Langevin forces. We have considered an incident field in a linearly
polarized coherent state (driving field) and vacuum in the perpendicular
polarization and calculated the noise spectra of the amplitude and phase
quadratures of the output field for two orthogonal polarizations. We analyze
different configurations depending on the total angular momentum of the ground
and excited atomic states. We examine the generation of squeezing for the
driving field polarization component and vacuum squeezing of the orthogonal
polarization. Entanglement of orthogonally polarized modes is predicted. Noise
spectral features specific of (Zeeman) multi-level configurations are
identified.
