Charge repulsion also works between QCA cells if they are placed side by side.
Here, two closely spaced cells start in the "0" state. They mimic each other because by being in the same state, the charges are spaced as far from one another as possible.
But then, the top input wire is charged positive. The positive charge on the top left dot runs away from the positive wire. Its movement then causes all of the other charges to move, flipping both QCA cells into a "1" logic state.
