Effect of the Measurement on the Decay Rate of a Quantum System
We investigate how the measurement influences the decay of a quantum unstable system. The latter is represented by an electron tunneling from a quantum dot to a reservoir of empty states. The dot is coupled to a ballistic pointcontact acting as a detector. The entire setup can be realized in actual mesoscopic experiments. Using a microscopic description of the whole system, we derived a new type of rate equations and calculated the energy distribution of the tunneling electron. We show that the continuous measurement of the unstable system does not influence its decay rate, while the energy distribution of the tunneling electron is strongly affected. This is in contradiction with rapidly repeated measurements, which are expected to slow down the decay rate (Quantum Zeno effect).