The quantum interference experiment as seen under an electron microscope. Using bilayer graphene, scientists controlled the trajectory of an anion in the material (in red). They made its wave go around an island containing a magnetic field and other anions (in green) and then brought it back together with the original wave to study its properties. The electrical gates (in dark gray) allow scientists to direct the anions along specific paths in the material and also determine the density of electrons in the island.