Electromagnetically Induced Transparency In Combined-λ-type Atom

Electromagnetically induced transparency (EIT) is an effect of quantum coherence or interference when laser interacts with atoms. It is the foundation of quantum information storage, subluminal, laser without inversion. The research of EIT only reach at several laser interact with several-level atom recent year. The condition of more lasers interacting with more-level atom is too complex to study. In this work, considering the solution of optical Bloch equation in steady state.Firstly, by numerical calculation, we predict the EIT of n-Λ-type atom (2n laser interact with 2n+1 level atom) in the condition of the collaboration of n-two-photon resonances. The result of numerical calculation agrees with theoretical prediction. At the same time, we compare the ability of refracting of different n-Λ-type atom. Then we do research on the EIT of N-type atom system, N-Λ-type atom system and N-2Λ-type atom system, by numerical calculation. Finally, we compare the ability of refracting of them.