Electromagnetically induced grating in a degenerate open two-level system

Summary form only given. The demonstration of electromagnetically induced transparency (EIT) on an atomic transition along with its potential possibilities of applications has driven a much deeper investigation on the atom-field interaction, specifically concerning to the level degeneracy. This coherent response of an atomic system can also be studied through four-wave mixing (FWM), a process named electromagnetically induced grating (EIG) which present the advantage of being a background free technique. In this work we present results on the observation of subnatural EIG resonance in a degenerate open two-level system where the Zeeman degeneracy plays a important role. The experiment is performed in cold cesium atoms obtained from a MOT and employs the conventional backwards FWM configuration.