F. Stefan Tautz

A sheet of graphene is a lattice of carbon atoms arranged like a honeycomb. Electrons in it zip around so fast they seem to have no mass, just like light. When a powerful laser pulse hits such a sheet, the electrons get a kick and start accelerating. Their path can be compared to a road with occasional barriers — the forbidden zones.

A wafer-thin film of organic molecules was grown on a silicon substrate. In this film, as if on a sheet of graph paper, tiny "pens"—artificial atoms — were laid out with the tip of a scanning tunneling microscope.

Inside a microscope that sees individual atoms, it's cold and silent: the temperature is around -268°C, and the interior is in perfect vacuum. To place individual iron atoms on such a stage, you usually need a direct 'corridor' from the evaporator to the sample. But in the coldest instruments, that corridor is blocked by thermal shields, making deposition a puzzle.