From Habr:
I came up with a quantum algorithm to find the shortest path in a graph. Cheap and angry. On an element base available to any DIY adherent. We take a solder, wires and a set of low-power resistors. We spread a diagram in which the weight of the path is encoded by the resistance of the resistor. Cut 220 to the points between which we are looking for a path. Where you have drowned, there is the shortest path. Rapid action is amazing, complete parallelism.