Observation of two dual electromagnetically induced transparencies in cold $^{87}Rb$ atoms

We demonstrate the observation of two dual electromagnetically induced transparency (EIT) peaks simultaneously in $D_{2}$ line transition of $^{87}Rb$ atom in a sample of cold $^{87}Rb$ atoms trapped in a magneto-optical trap (MOT). These dual EIT peaks are generated from two different N-systems in $D_{2}$ line transition of $^{87}Rb$ atom. The dependence of this dual EIT spectral feature on driving beams (textit{i.e.} coupling and control beams) intensity and detuning has been investigated in detail for both the N-systems. The results show that the dual EIT spectral features in both the N-systems can be manipulated by varying the intensity and detuning of the driving beams. The two N-systems have been modelled theoretically using a density matrix formalism and results have shown a good agreement with the experimental observations.