Quantum Beam Scattering—Beam’s Coherence Length, Which-Path Information andWeak Values

The conventional theory of neutron beams interacting with many-body systems treats the beam as a classical system, i.e., its dynamical variables appearing in quantum dynamics scattering process not operators but only c-numbers. Moreover, neutrons are described plane waves, concept neutron’s (finite) coherence length is here irrelevant. same holds for electron, atom or X-ray scattering. This simplification results full decoupling probe particle’s from scatterer—a well-known fact also reflected standard formalism time-correlation functions (see textbooks). Making contact modern quantum-theoretical approaches (e.g., entanglement, “which-path information” versus interference, von Neumann measurement, Weak Values (WV), etc.), new observable effects non-relativistic may be exposed and/or predicted, instance, momentum-transfer deficit and an intensity protons hydrogen-containing samples. A WV-theoretical treatment provided, which explains both these “deficit effects” first principles on equal footing.