The World’s Smallest Computer

In a computer, the logic elements are the main components with computational abilities, and they are what make the machine a computer. IBM in 2001-2002 has managed to make these logic elements, approximately 260,000 times smaller than the ones used in highly advanced computer chips. IBM was not only successful in constructing these elements, but they also connected them and made them compute, which means it was a fully functional model.




IBM scientists achieved this feat of miniaturizing digital-logic elements by using a clever molecule cascading technique. They used an arrangement of carbon monoxide molecules on a copper surface, and were able to trigger a cascading effect on these molecules to work the AND and OR digital-logic functions, retrieval, and data storage.


Domino Pieces


Molecules of carbon monoxide have the capacity to be arranged in a configuration that is energetically metastable on a copper surface. The arrangement used by the scientists looked like two lines of domino pieces curving towards each other, and having a single domino piece at the end, which could be toppled by either one of the lines. This constituted the OR gate, and the input would nudge the domino to create a cascading effect or the input could be zero that would not create any nudge.


An Egg Carton


The placement of carbon monoxide molecules in a natural formation on crystalline copper grid enabled IBM scientists to form a domino code for logical calculations. The molecules and the grid are quite similar to tennis balls being placed in an egg carton. The balls being larger than the spacing of the lattice are not able to nestle down fully in the hollow space, and will be unstable.




The carbon monoxide molecules will be in a similar situation, and IBM scientists found that when they arranged the molecules in three sets of inverted V shapes, they could naturally rearrange themselves by the motion of the central molecule. The scientists were then able to link molecule pairs in a way that facilitated the reformation of new inverted V shapes in a cascading motion.


The Process


The toppling of the crucial piece of the arrangement and changing the pattern of the carbon monoxide molecules was achieved by using a STM (Scanning Tunneling Microscope). The changed pattern would then be used to perform particular calculation. Hence, the STM was used as an input device to bring changes into the domino coded circuitry. The computation was possible by each cascade that carried single bit information. 


A New Frontier


With this cascading technique, IBM managed to fabricate a complex circuit, which was a three-input sorter measuring 12 x 17 nanometers. One nanometer is billionth part of a meter, which means you could fit about 190 billion of these sorters on the top of a pencil eraser that is about quarter inch in diameter. A computer circuitry at such a nanometer scale was a milestone in computer technology, and IBM was able to show to the world that properties of small structures could be effectively harnessed. This opens new avenues in information processing approaches, and further research is under way.