Nano Lett. doi:10.1021/nl803800c (2009)

The data packed as magnetic regions on hard disks will fade in just a few decades, as atoms vibrate and reorient themselves.

But an iron nanoparticle sheathed inside a carbon nanotube could form a protected data element, whose position would remain stable at room temperature for more than a billion years, report Alex Zettl of the University of California, Berkeley, and his team.

By applying an electric pulse, the researchers controllably shift the nanoparticle back and forth. Its position — corresponding to a '0' or a '1' — can be easily read by measuring electrical resistance across the nanotube.

A device made of bundles of individually positionable nanotubes could form an ultra-high-density data store, readable for any practical time scale, the researchers think.