Tightly Localized Stationary Pulses in Multi-Level Atomic System
  We show the pulse matching phenomenon can be obtained in the general multi-level system with electromagnetically induced transparency (EIT). For this we find a novel way to create tightly localized stationary pulses by using counter-propagating pump fields. The present process is a spatial compression of excitation so that it allows us to shape and further intensify the localized stationary pulses, without using standing waves of pump fields or spatially modulated pump fields. 
Xiong-Jun Liu, Xin Liu, Zheng-Xin Liu, L. C. Kwek and C. H. Oh