Which slit: successive single particles start from positions biased toward the openings. After a particle passes a slit, detection farther downstream smoothly prepares a broad Gaussian centered on that slit. Its width allows the particle to continue more gently while keeping the new wave clear of the wall. The particle keeps its position and follows the spreading wave. Actual detector hits accumulate across particles. This is an illustrative preparation with biased launches; its histogram is not an exact Born-rule prediction.

A quantum wave packet travels according to the Schrodinger equation. The barrier splits it into two coherent parts; after the slits those parts overlap and form interference.

Wave brightness is scaled by the Born density. The phase view colors the argument of the same wave: blue at +π/2, red at −π/2, and magenta at ±π. A purple density layer remains visible where the phase colors fade near phase 0. The legend shows this blend at full reference brightness.

A Bohmian particle has a definite position, and its velocity is determined by the probability current. The guiding law is:

The Pauli option adds an extra term in the current arising from the spin. Paths can change while the same wave density still governs the pattern.