Miniaturization has reached a new level as researchers at the German Center for Free-Electron Laser Science and IBM (press kit) have created a magnetic data storage unit that uses only 12 atoms to a bit, or 96 atoms to a byte. In a conventional magnetic hard disk, over half a billion atoms are used for a single byte and the area needed is hundreds of times larger.
Key to this setup is the use of antiferromagnetism. Ferromagnets, like those used in a hard disk, produce a magnetic field when the spins of the atoms all line up. Antiferromagnets contain atoms whose spins are in opposite directions. This causes a pair or group of atoms to be magnetically neutral, which then allows them to be packed much closer together. The bit itself would be stored in the spin of a single atom in the pair or group.
Initially the atoms were just in pairs, but the researchers had to combine together six pairs to a bit, for a total of 12 atoms, as quantum effects were blurring the data with fewer atoms. In fact the system had to be cooled to just 5 K to overcome the quantum effects with 12 atoms, but the researchers believe 200 atoms to a bit should be enough for use at room temperature. If the quantum effects could be harnessed though, a bit could become even smaller. Fortunately this setup can be used for studying that as it is at the edge of quantum and classical mechanics.