Wave-particle dualism in matter wave interferometry

Neutron interferometry is a unique tool for investigations in the field of particle-wave dualism because massive elementary particles behave like waves within the interferometer. The invention of perfect crystal neutron interferometers providing widely separated coherent beams stimulated a great variety of experiments with matter waves in the field of basic quantum mechanics. The phase of the spatial and spinor wave function become a measurable quantity and can be influenced individually. High degrees of coherence and high order interferences have been observed by this technique. The 4π-symmetry of a spinor wave function and the mutual modulation of nuclear and magnetic phase shifts have been measured in the past. Recent experiments dealt with polarized neutron beams, which are handled to realize the spin-superposition of two oppositionally polarized subbeams resulting in final polarization perpendicular to both initial beam polarizations. The different action on the coherent beams of static and dynamic flippers have been visualized. Monolithic multicrystal arrangements in Laue position can also be used to achieve an extremely high energy (10-9 eV) or angular resolution (0.001 sec of arc). This feature is based on the Pendelloesung interference within the perfect crystal. A transverse coherence length up to 6.5 mm is deduced from single slit diffraction experiments. (Auth.)