Study of EIT resonances in an anti-relaxation coated Rb vapor cell

We study the sign of resonances obtained in electromagnetically induced transparency (EIT). Resonances of both kinds-bright (corresponding to enhanced absorption) and dark (corresponding to reduced absorption)-are obtained when the frequency of a probe beam is scanned. The experimental results, presented earlier, use magnetic sublevels of a hyperfine transition in the D-1 line of Rb-87 along with a magnetic field of 27 G. The atoms are contained in a vapor cell at room temperature, and with anti-relaxation coating on the walls. A quantitative theoretical model, which reproduces the experimental results quite well, is presented for the first time. The model solves the density matrix of the sublevels involved, and uses two regions-one with both the light and magnetic field, and the second without light and just a magnetic field. This ability to have both bright and dark resonances promises applications in sub- and super-luminal propagation of light. (C) 2018 Elsevier B.V. All rights reserved.