Influence of interaction time and population redistribution on the localization of atomic excitation through electromagnetically induced transparency

We study numerically the localization of atomic excitation based on the dark states formed through electromagnetically induced transparency using interfering coupling beams. In particular, we examine the formation of dark states in a system exhibiting hyperfine splitting, including the effects of optical pumping in this multilevel system, laser polarization, and finite interaction time, and explore the conditions that lead to optimal spatial resolution of the excitation. We find that optimal localization requires long interaction times, due to the slow approach of the atomic system to steady state near the nodes of the standing wave pattern.