Saverio Pascazio

On a possible reduction of the interference term due to statistical fluctuations

Abstract We study of a neutron interferometry experiment when an absorber is present in one of the two routes of the interferometer, and show that if the microscopic fluctuations of the absorber are taken into account, the interference term is reduced to a smaller value than the simple quantum-mechanical one. This new effect becomes dramatically important when the absorbers transmission probability is very low. The problem is also discussed from the point of view of the measurement in quantum mechanics.

Superselection rules and fluctuations in the Many-Hilbert-Spaces approach to quantum measurement

The interaction between a macroscopic detector and a quantum system is studied by means of a simple model in the context of the Many-Hilbert-Spaces approach, and it is shown that statistical fluctuations play a determinant role in the description of the detector. An order parameter is introduced, in terms of which aquantitative definition of wave-function collapse can be given. The meaning of the superselection charges of the Many-Hilbert-Spaces is also clarified, and an inequivalent representation is given in the limit of infinite number of elementary constituents of the detector. Finally, this approach is compared to other proposals in the literature.

Blending two alternative approaches to quantum measurement

Abstract Two different approaches to the problem of measurement in quantum mechanics are combined. In this way, new insights are obtained into the mechanism engendering the loss of coherence suffered by a quantum mechanical system when interacting with a macroscopic apparatus.