Freezing light: ultraslow EIT polariton in a three-level medium

Summary form only given. A large temporal (frequency) dispersion accompanying electromagnetically induced transparency (EIT) leads to drastic slowing down of the group velocity of light, v/sub g/=c/(wdn(w))/dw/spl Lt/c has been shown in recent experiments. We show that by using spatial dispersion, which is due to an atomic motion, it is possible to freeze the light, i.e. to bring it to a complete stop or even reverse the direction of its propagation. We consider two different types of atomic motion: (i) uniformly moving atoms, i.e. atomic beam or uniformly moving sample, and (ii) atomic gas with a thermal distribution of the velocities in the cell which is at rest.