The Einstein’s program enables a theoretical economy for quantum double slit experiment, in its wave-particle duality behavior, with the unification of first and second quantifications for light and matter. It introduces a space-like amplitude function u(r,t), which completes the usual time-like functions ψ(r,t) of quantum mechanics and quantum fields. The Einstein’s program is founded upon a scalar field propagating at speed of light c. It forms a common relativist framework, for classical and quantum properties of matter and interactions. Matter properties derive from standing waves, and interactions from progressive waves. The classical domain arises in the geometrical optics approximation, when frequencies are infinitely high, and then hidden. The quantum domain corresponds to wave... optics approximation. Adiabatic variations of frequencies yield electromagnetic interaction and dynamical laws of energy-momentum conservation and least action principle.