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# ANTONINO MESSINA

## Oscillations of the purity in the repeated-measurement-based generation of quantum states

• Autori: Militello, B.; Yuasa, K.; Nakazato, H.; Messina, A.
• Anno di pubblicazione: 2008
• Tipologia: Articolo in rivista (Articolo in rivista)
• Parole Chiave: Foundations of quantum mechanics; Quantum optics; Coherent control of atomic interactions with photons;

### Abstract

Repeated observations of a quantum system interacting with another one can drive the latter toward a particular quantum state, irrespective of its initial condition, because of an effective nonunitary evolution. If the target state is a pure one, the degree of purity of the system approaches unity, even when the initial condition of the system is a mixed state. In this paper we study the behavior of the purity from the initial value to the final one, that is, unity. Depending on the parameters, after a finite number of measurements, the purity exhibits oscillations that brings about a lower purity than that of the initial state, which is a point to be taken care of in concrete applications.