  We analyze the experimental observations reported by Fischer et. al. [in
Phys. Rev. Lett. 87, 040402 (2001)] by considering a system of coupled unstable
bound quantum states A and B. The state B is coupled to a set of continuum
states C. We investigate the time evolution of A when it decays into C via B,
and find that frequent measurements on 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 B which allows for the anti-Zeno effect.
