  Electromagnetically induced transparency (EIT) and absorption (EIA) are
quantum coherence phenomena which result due to interference of excitation
pathways. Since the first realization of EIT in 1991 and EIA in 1998,
mechanisms behind these remarkable effects have been studied extensively,
therefore both are relatively easily achievable in controlled environments.
Combining EIT and EIA with Rydberg atoms have provided utility in various
research fields such as interacting many body systems, quantum optics and
quantum information science. We propose an analysis of Rydberg-EIT and
Rydberg-EIA effects in cold Cs and Rb atomic ensembles in a four-level ladder
type scheme with self-consistent mean field approach. Our results are
consistent with experimental realizations and provide a many-body method to
simulate EIT-EIA cross-over.
