Franz Himpsel and a team from the University of Wisconsin have experimented with a scanning tunnelling microscope (STM) travelling over a silicon surface, the tip of which can detect the presence or absence of a single silicon atom, which can be used to represent binary zero or binary one.
At this stage, the data silicon atom must be separated from its neighbours by placing it in a five-by-four cell of atoms, the scheme therefore requiring 20 atoms in all to securely store one bit, according to data published on the university's Web site.
This translates into a storage density of 250Tbits per square inch, which is 2,500 times denser than the 100Gbits per square inch that can be stored on the most advanced conventional hard disk drives, Himpsel said.
The atomic memory on the silicon device has been tested for reliability and speed. Reading data can be achieved at a reasonable rate, although slower than in hard disk drives, but writing data at the maximum data density is currently too slow to be practical, according to Himpsel.
One potential way to speed up data reads and writes would be to use a large number of STMs in parallel, with up to 1,000 STM tips in an array, Himpsel said.
IBM is also conducting research into data storage using a variation of the STM, and believes its Millipede technology, capable of storing 1Tbits per square inch, could start appearing in products as early as 2005.
The idea for an atomic memory storage device was conceived as far back as 1959 by the US physicist Richard Feynman who described in a talk a memory cube containing 125 atoms being able to store one bit.
Further information on the atomic memory research can be found at http://uw.physics.wisc.edu/~himpsel/memory.html.