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Electromagnetically Induced Transparency


Chitra Rangan



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Electromagnetically induced transparency (EIT) is a technique whereby a medium otherwise opaque to radiation of a particular frequency can be made transparent at that frequency by applying radiation of an appropriate second frequency. EIT demonstrates numerous current applications, with a notable focus on its utilization within the field of quantum information. Given the absence of an established theory of EIT in atomic ensembles, my primary focus is to develop theoretical models that describe both the quantum mechanical origin of EIT as well as the effect of interatomic interactions. In this thesis, I present two theoretical models of EIT in an ensemble of three-level atoms in a lambda configuration. The ensemble is modelled by a 5-level quantum system with the mean-field interactions between atoms modelled by decoherence terms. The dynamics of the ensemble are calculated by solving the Lindblad Master Equation for the density matrix. From the density matrix, the polarizability, and the frequency-dependence of the electric susceptibility and the group refractive index are calculated. A strong dependence on the density of the ensemble is observed. Additionally, I explore the propagation of a Gaussian probe pulse within an atomic medium composed of three-level Λ systems (3LΛS). By solving the coupled Maxwell and Liouville-von Neumann equations under the assumption of slow variations in the electric field across both space and time, I showed that intriguing results emerge, particularly concerning the influence of density on pulse dynamics. Furthermore, comparing the two models over a range of ensemble number densities, it was seen that despite achieving a favorable transparency window by increasing the number density in the first model, the second model shows that EIT is not observed at high densities.