Researchers in the Netherlands have created a microscopic storage system that encodes every bit with a single atom -- allowing them to fit a kilobyte in a space under 100 nanometers across. That translates to a storage density of about 500 terabits per square inch.

For comparison, those 4-terabyte hard drives you can buy today are about 1 terabit per square inch. That's because, unlike this new system, they use hundreds or thousands of atoms to store a single bit. "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," explained Sander Otte, lead scientist at Delft University of Technology, in a news release. Because chlorine on copper forms into a perfectly square grid, it's easy (relatively, anyway) to position and read them. If the chlorine atom is up top, that's a 1; if it's at the bottom, that's a 0. Put 8 chlorine atoms in a row and they form a byte.

The data the researchers chose to demonstrate this was a fragment of a Feynman lecture, "There's plenty of room at the bottom" (PDF) -- fittingly, about storing data at extremely small scales. The chlorine-copper array is only stable in a clean vacuum and at 77 kelvin -- about the temperature of liquid nitrogen. Anything past that and heat will disrupt the organization of the atoms. The research was published today in the journal Nature Nanotechnology.