Hindered decay of an unstable system: A quantum zeno effect

Michael B. Mensky

Kavan Kishore Modi, Anil Shaji

Saverio Pascazio

The time evolution of an unstable quantum system coupled with an external "measuring" apparatus is investigated. A quantum Zeno effect (hindered decay) or an inverse quantum Zeno effect (accelerated decay) may take place, depending on the features of the coupling and the response time of the apparatus. The transition between the two regimes is analyzed.

Braulio Gutiérrez–Medina, Martin C. Fischer, Mark G. Raizen

P. Facchi, S. Pascazio

The time evolution of an unstable quantum mechanical system coupled with an external measuring agent is investigated. According to the features of the interaction Hamiltonian, a quantum Zeno effect (hindered decay) or an inverse quantum Zeno effect (accelerated decay) can take place, depending on the response time of the apparatus. The transition between the two regimes is analyzed for both pulsed and continuous measurements.

E. Mihóková, Saverio Pascazio, Lawrence S. Schulman

The lifetime of an unstable atom can be extended by watching it closely, i.e., illuminating it with an intense electromagnetic field of appropriate frequency. This is an example of ``dominated evolution'' and is closely related to the so-called ``quantum Zeno effect.'' For a metastable atom bathed in a laser beam at the frequency of another of its transitions, we obtain an expression for the modified lifetime as a function of beam intensity. This provides an example of the quantum Zeno effect on a truly decaying system, and also should be useful for probing short distance features of atomic wave functions.