In an attempt to address the problem of a digital dark age engineers at Berkeley have developed a technique called Nanoscale Reversible Mass Transport for Archival Memory that is intended to combine high bit-density and deep-time survival:
We have developed a new mechanism for digital memory storage with the potential to store data with both long lifetime and high density. Our memory device consists of a crystalline iron nanoparticle enclosed in a multiwalled carbon nanotube. The nanotube can be reversibly moved through the nanotube by applying a low voltage, “writing” the device to a binary state represented by the position of the nanoparticle. The state of the device can then be subsequently read by a simple resistance measurement.
The abstract of the paper claims thermodynamic stability in excess of one billion years with data density of 1012 bits/in2.