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

B. Militello, K. Yuasa, H. Nakazato, A. Messina
2008 Physical Review A. Atomic, Molecular, and Optical Physics  
Repeated observations of a quantum system interacting with another one can drive the latter toward a particular quantum state, irrespectively of its initial condition, because of an effective non-unitary 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
more » ... , 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.
doi:10.1103/physreva.77.042109 fatcat:d3ilatuhavcj7iemtbuiiwjpaa