Hidden observables in neutron quantum interferometry
ABSTRACT Neutron interferometry using monolithic perfect single crystals has become an important tool for fundamental, nuclear, and solid-state physics research. New features of quantum mechanics become measurable by means of neutron interferometry. Such features are quantum phases, which provide a more direct access to properties of wave functions and permit wave function reconstruction, and wave function engineering. Most recently, new experiments concerning off-diagonal and non-cyclic geometrical phases, confinement induced phases, and contextuality related experiments have been performed. These experiments show an intrinsic entanglement of different degrees of freedom of a single particle. Proper post-selection experiments yield to more quantum complete experiments and may help to make quantum mechanics less mystic. Unavoidable quantum losses may play an important role to explain the transition from the quantum to the classical world. All these investigations concern the heart of quantum mechanics and demonstrate the non-local feature of this theory.
Article: Neutron interferometry.[show abstract] [hide abstract]
ABSTRACT: Neutrons are elementary massive particles consisting of one “up” and two “down” quarks; but in neutron interference experiments they exhibit wave features only. In this case, the ► wave function describing thermal neutrons can be split, reflected and superposed coherently by means of dynamical Bragg diffraction from a perfect silicon single crystal. The coherent beam parts are widely separated, and they can be influenced individually by nuclear, magnetic or gravitational interaction. This technique has first been tested 1974 at a small 250 kW TRIGA reactor in Vienna . The monolithic design of such interferometers guarantees the parallelism of the reflecting lattice planes up to a fraction of their lattice distance, which is a necessary condition for coherent beam splitting. This experimental method has been adapted from X-ray interferometry developed earlier . The figure shows various types of such interferometers as they are used now at several neutron sources around the world.Science 12/1993; 262(5138):1384-5. · 31.03 Impact Factor