Abstract
We analyze the experimental observations reported by Fischer et al. [M.C. Fischer, B. Gutierrez-Medina, M.G. Raizen, Phys. Rev. Lett. 87 (2001) 0404021 by considering a system of coupled unstable bound quantum states I A) and I B). ne state I B) is coupled to a set of continuum states I C 0 (omega)). We investigate the time evolution of I A) when it decays into I C (9 (omega)) via I B), and find that frequent measurements on I A) leads to both the quantum Zeno effect and the anti-Zeno effects depending on the frequency of measurements. We show that it is the presence of I B) which allows for the anti-Zeno effect. (c) 2007 Elsevier B.V All rights reserved.