title: Resonant gain suppression and superluminal group velocity in a multilevel system.
abstract: We investigate the interaction of an open (N + 1)-level extended V-type atomic system (i.e. a closed (N + 2)-level atomic system) with N coherent laser fields and one incoherent pumping field through both analytical and numerical calculations. Our results show that the system can exhibit multiple resonant gain suppressions via perfect quantum destructive interference, which is usually believed to be absent in closed three-level V system and its extended versions involving more atomic levels, with at most N - 1 transparency windows associated with very steep anomalous dispersions occurring in the system. The superluminal group velocity of the probe-laser pulse with at most N - 1 negative values can also be generated and controlled with little gain or absorption.
authors.affiliation: College of Physics, Jilin University, Changchun 130012, China.
authors.forename: Cui-Li
authors.initials: CL
authors.lastname: Cui
authors.forename: Chang-Bao
authors.initials: CB
authors.lastname: Fu
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.forename: Qian-Qian
authors.initials: QQ
authors.lastname: Bao
authors.forename: Huai-Liang
authors.initials: HL
authors.lastname: Xu
authors.forename: Jin-Hui
authors.initials: JH
authors.lastname: Wu