Atomic memory. Coloured scanning tunnelling microscope (STM) image of the surface of a storage medium that uses single atoms to represent data. Individual atoms (yellow) hold data in the same way as the pits on a CD. This surface comprises a substrate of gold and silicon. Extra silicon atoms sit on the surface. Such data can be written and read using an STM. This research was done at the Universities of Basel, Switzerland, and Madison, Wisconsin, USA.