Electromagnetically Induced Transparency is a coherent optical nonlinearity that renders a medium transparent window over a narrow spectral range within an absorption line. Extreme dispersion is also created within this transparency window which leads to slow light as described below. It is a quantum interference effect that permits the propagation of light through an otherwise opaque atomic medium. Observation of EIT involves two optical fields (highly coherent light sources, such as lasers) which are tuned to interact with three quantum states of a material. The probe field is tuned near...