Neutron Interferometer: Gravity-Induced Quantum Phase (2D)

A single silicon crystal, cut into three parallel slabs, splits a neutron beam into two coherent paths that enclose a small loop of area and recombine at the far plate — the Colella–Overhauser–Werner (COW) interferometer that first showed gravity acting directly on a quantum matter wave's phase, not just on a classical trajectory. This 2D simulator renders the real geometry across three linked panels: an end-on rotation dial you can drag to tilt the crystal about the beam axis, a side-on path diagram whose two branches visibly separate by an amount ∝ sin φ as neutrons flow through them, and a live fringe curve plus phasor (vector-sum) diagram showing exactly why the O-beam and H-beam detector rates oscillate. Wavelength and loop-area sliders scale the fringe spacing exactly as they do in the historical 1975 experiment, and the theory panel documents a numerical check on the gravitational-phase formula itself.