当一个梯形四能级原子系统的中间两个能级分别与真空辐射场相互作用耦合到基态和激发态时,自发衰变路径间的量子干涉效应导致了V和Λ型的真空场诱导相干(VIC)。利用半经典理论,分别讨论了这两种类型的VIC对单光子和双光子电磁诱导透明的影响,并发现Λ型的真空场诱导相干增强双光子的吸收,而对单光子的吸收几乎无影响;V型的真空场诱导相干抑制单光子和双光子的吸收。

When the two middle levels in a four-level ladder atom are coupled with a ground and a excited levels by the same vacuum radiation fields,respectively,there are two kinds of vacuum-induced coherence (VIC):V and Λ-type VIC;due to the quantum interference effects between the spontaneous decay channels. The effects of the VIC on the electromagnetically induced single- and two-photon transparency are studied by the semiclassical theory,respectively. The Λ-type VIC enhances the two-photon absorption,but has no effect on the single photon absorption;the V-type VIC suppresses the single and two-photon absorption.