Physics
The Thouless pump (1983) slowly varies a 1D Hamiltonian periodically. After each full cycle, exactly one quantum of charge is transported — protected by the Chern number of the occupied band's Berry phase.
The SSH-like model has hopping:
t₁ = t(1 + δ cos φ), t₂ = t(1 + δ sin φ)
As φ sweeps 0→2π, charge centers shift by one lattice spacing. The Chern number C = 1 means this is topologically robust — small perturbations can't change the quantized transport.
Colors: bright = high electron density, dark = low. Watch the density wave march rightward.