The evolution of a quantum mechanical system can be profoundly modified by the action of an external agent, such as a detection apparatus or a field. If quantum measurements are performed on the system, its evolution can be hindered or enhanced, depending on the physical features of the system itself and the interaction. The quantum Zeno effect consists in the hindrance of the evolution, the inverse quantum Zeno effect in its enhancement. We shall discuss both these effects by considering some examples in quantum optics and quantum electrodynamics and shall critically analyze the notion of quantum measurement: the Zeno effects take place both if the measurements are ``pulsed" and almost instantaneous or ``continuous" and of long duration. We also discuss the profound differences between oscillating systems, whose Poincare' time is finite, and unstable ones. For the latter, the Zeno effects are much more interesting and transitions become possible between a Zeno and an inverse Zeno regime.
Quantum Zeno and inverse quantum Zeno effects
FACCHI, PAOLO;PASCAZIO, Saverio
2001-01-01
Abstract
The evolution of a quantum mechanical system can be profoundly modified by the action of an external agent, such as a detection apparatus or a field. If quantum measurements are performed on the system, its evolution can be hindered or enhanced, depending on the physical features of the system itself and the interaction. The quantum Zeno effect consists in the hindrance of the evolution, the inverse quantum Zeno effect in its enhancement. We shall discuss both these effects by considering some examples in quantum optics and quantum electrodynamics and shall critically analyze the notion of quantum measurement: the Zeno effects take place both if the measurements are ``pulsed" and almost instantaneous or ``continuous" and of long duration. We also discuss the profound differences between oscillating systems, whose Poincare' time is finite, and unstable ones. For the latter, the Zeno effects are much more interesting and transitions become possible between a Zeno and an inverse Zeno regime.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.