EIT and AT: Two Similar but Distinct Phenomena in Two Categories of Three-Level Atomic Systems

Abstract

Electromagnetically Induced Transparency (EIT) and Autler-Townes (AT) are two phenomena that could be featured by a variety of three-level atomic systems. The considered phenomena, EIT and AT, are similar "looking" in the sense that they both are characterized by a reduction in absorption of a weak field in the presence of a stronger field. In this paper, we explicitly set the threshold of separation between EIT and AT in a unified study of four different three-level atomic systems. Two resonances are studied and compared in each case. A comparison of the magnitudes of the resonances reveals two coupling field regimes and two categories of three-level systems.