Enhancing electromagnetically-induced transparency in a multilevel   broadened medium
  Electromagnetically-induced transparency has become an important tool to control the optical properties of dense media. However, in a broad class of systems, the interplay between inhomogeneous broadening and the existence of several excited levels may lead to a vanishing transparency. Here, by identifying the underlying physical mechanisms resulting in this effect, we show that transparency can be strongly enhanced. We thereby demonstrate a 5-fold enhancement in a room-temperature vapor of alkali-metal atoms via a specific shaping of the atomic velocity distribution. 
M. Scherman (LKB - Jussieu), O.S. Mishina (LKB - Jussieu), P. Lombardi   (LKB - Jussieu), E. Giacobino (LKB - Jussieu), J. L...
quant-ph