  We present the theory of a new method to slow a linearly polarized probe
pulse as it propagates through a duplicated two-level system driven by an
orthogonally polarized control field. The method makes use of Zeeman coherence
oscillations (CZO) that arise in the atomic system because of the spatial and
temporal modulation of the total polarization. This method exhibits properties
similar to those that rely on the electromagnetically induced transparency
(EIT) but without the existence of any trapping state. We demonstrated also the
propagation of a dark polariton in the medium
