Measurement of the neutron lifetime and inverse quantum Zeno effect

Quantum mechanics predicts that the decay rate of unstable systems could be effectively modified by theprocess of the measurement of the survival probability. Depending on the intrinsic properties of the unstablesystem and the experimental setup for the observation, one could obtain the so called (direct) quantum Zenoand inverse quantum Zeno effects corresponding to a slowing down or a speeding up of the decay,respectively. We argue that the inverse quantum Zeno effect is in principle detectable at a percent levelfor the neutron decay in experiments with trapped ultracold neutrons. Conversely, this effect is basicallyundetectable in experiments in which the neutron lifetime is measured by measuring the decays of beams ofneutrons. As a test of our claim, we propose a simple qualitative correlation between the number of neutronsin the trap and the neutron lifetime: the larger the number, the faster the decay. Finally we discuss also thepresently available measurements of the neutron lifetime and address the issue of the possible discrepancythat has been reported among the results obtained by the different experimental techniques.