The device was created using a scanning tunnelling microscope, not only allowing the team to see the atoms, but also to move them. “You could compare it to a sliding puzzle,” said lead scientist Sander Otte. “Every bit consists of two positions on a surface of copper atoms and one chlorine atom that we can slide back and forth between these two positions. If the chlorine atom is in the top position, there is a hole beneath it – we call this a 1. If the hole is in the top position, then the bit is a 0.”
Because the chlorine atoms are surrounded by other chlorine atoms, except near the holes, they keep each other in place and the approach is said to be more stable and more suitable for data storage.
The researchers organised the memory in 8byte blocks. Each block has a marker made of the same type of ‘holes’ as the raster of chlorine atoms. Said to be inspired by QR codes, markers carry information about the precise location of the block on the copper layer. The code will also indicate if a block is damaged, for instance due to some local contaminant or an error in the surface. This is said to allow the memory to be scaled to big sizes, even if the copper surface is not entirely perfect.
Otte noted: “In its current form, the memory can operate only in very clean vacuum conditions and at liquid nitrogen temperature (77 K), so the storage of data on an atomic scale is still some way off. But we have certainly come a big step closer.”
