As a realization of the quantum Zeno effect, we consider electron tunneling
between two quantum dots with one of the dots coupled to a quantum point c
ontact detector. The coupling leads to decoherence and to the suppression o
f tunneling. When the detector is driven with an ac voltage, a parametric r
esonance occurs which strongly counteracts decoherence. We propose a novel
experiment with which it is possible to observe both the quantum Zeno effec
t and the parametric resonance in electric transport.