Subluminal light pulse propagation in a Λ-type atom-molecule coupled system

Abstract: We show theoretically the presence of electromagnetically induced transparency (EIT) like feature in a {\Lambda}-type atom-molecule coupled system. We demonstrate that EIT in such a systems has a sharp dispersion characteristic which is useful to slow down light propagation in a medium. The results of our model calculations show that, it is possible to achieve a time delay of the order of 1 ms for a probe field propagating a distance of 1 cm through a medium of ultracold diatomic molecules coupled to the continuum of atom-atom collisional states with a control field. This enables one to reduce the group velocity of the light much below 100 m/s with more than 25% transmission.