= Neutron interferometer
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A neutron interferometer coherently splits and recombines a <neutron> <matter wave>, converting a difference of <quantum phase> between paths into an output intensity change. A sample in one path can therefore be studied through its phase shift, even when its effect on transmitted intensity is small.
A perfect-crystal implementation uses several diffracting silicon blades machined from one crystal with a common base. <Bragg diffraction> splits the incident wave into paths, redirects them and recombines them in a geometry analogous to a <Mach-Zehnder interferometer>. The common base helps preserve relative alignment; thermal and vibration isolation protect phase stability. The institutional apparatus description includes the blade geometry and explains the importance of environmental isolation.<Neutron Interferometry and Optics Facilities by NIST>[overview, Fig. 2 and NIOF description: monolithic silicon blades, common base, and thermal/acoustic/vibration isolation]{ref}
Recombination measures a relative phase rather than an individual particle trajectory. Electric, magnetic, gravitational or material interactions can all contribute, so a quantitative result requires controls separating the desired phase from drifts and other path differences. The <Colella–Overhauser–Werner experiment> is a gravitational example.
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