For example, we may have a pair of large flat conductors, connected to a battery of voltage Δ Δ V . Then, we can run a single electron double-slit experiment, with the two slits on the two sides of the pair of conductors. If the electron takes time t to hit the screen, then we should observe a phase shift e Δ Δ V t / ℏ ℏ . By adjusting the battery voltage, we can horizontally shift the interference pattern on the screen.