On Electromagnetically Induced Transparency in N-systems in Cold 87rb Atoms

We have investigated two N-systems in D-2 line transition of Rb-87 atoms theoretically and experimentally. The study has been carried out with cold Rb-87 atoms trapped in a magneto-optical trap. Each N-system has shown dual electromagnetically induced transparency (EIT) structure in probe transmission, which is qualitatively explained using dressed-state picture. The dependence of spectral features of N-systems on coupling and control beams strength and detuning has been investigated. The results show that the dual EIT spectral features in both the N-systems can be manipulated by varying the strength and detuning of coupling and control beams. The numerical modeling of the systems using density matrix formalism also explains the experimentally observed results.