2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89807Trapped state definition for 3-level atoms in Lambda configuration, is a very restrictive one, and for the case of unpolarized beams, this definition no longer holds.We introduce a more general definition by using a reference frame rotating with the frequency of the control field, obtaining a temporal windowing for the trapped population.This amounts to a time quantization of the coherent population transfer, making possible to study the phase coherence in trapped light.4 pages, 3 eps figures. Submitted to Journal of Modern OpticsQuantum Physicstext