Coherence and Decoherence in Neutron Optics

Recent neutron interferometer experiments focused on coherence measurements and have shown that coherence features are determined by the beam preparation only. The wave function contains information about the particle and about the beam preparation simultaneously which signalizes the connection between quantum system and apparatus. Further experiments investigated the question of quantum decoherence and how a quantum system can evolve into a classical system. The experiments have been performed with a perfect crystal neutron interferometer at the high flux reactor of the Institut Laue‐Langevin in Grenoble. The distinction between dephasing and decoherence will be discussed.