Dispersive properties of electromagnetically induced transparency

Abstract
An atomic transition that has been made transparent by applying an additional electromagnetic field exhibits a rapidly varying refractive index with zero group velocity dispersion at line center. A 10-cm-long Pb vapor cell at an atom density of 7×1015 atoms/cm3 and probed on its 283-nm resonance transition has a calculated optical delay of 83 ns [(c/VG)=250].