UK Scientists Make Transistor One Atom Long, 10 Atoms Wide
Bibek Paudel points out a story about the latest step forward in the development of nano-scale circuits. Researchers from the University of Manchester have created some of the smallest transistors ever, measuring only one atom by 10 atoms. The transistors are made out of graphene, which has the potential to replace silicon in the never-ending hunt for smaller computer technology. From NewScientist:
"There are other kinds of prototype transistors in this size range. But they usually need supercooling using liquid gas, says Novoselov. The new graphene devices work at room temperature. Such prototypes are typically made by building one atom at a time, or wiring up individual molecules. Those approaches are complex and impractical, Novoselov says. By contrast, the graphene transistors were made in the same way that silicon devices are, by etching them out of larger pieces of material. 'That's their big advantage,' he says."
Seriously, sometimes I feel the line between science and magic gets fuzzy. A transistor one atom by 10 atoms? That's on such a small scale that is so hard to comprehend that it'd almost be easier to hand-wave it and just say "it's magic."
In Eric Drexler's book "Nanosystems, he carefully analyzes questions like this regarding the possible failure modes of atomically-precise devices. The book goes through the math in detail. The short answer is that even with fairly pessimistic assumptions (e.g. that a single-atom defect created during manufacture or afterwards by cosmic rays or other radiation will completely destroy a particular functional sub-unit), you can still design highly robust devices.
The most obvious way is to build in some level of redundancy. Naively you can have dozens of redundant sub-units, and use things like "majority voting" to pull out the signal from the noise. In practice there are more elegant ways to do this (e.g. error correction). Many modern chips do indeed have some redundancies so that even with manufacturing defects, the chip still runs (perhaps with some reduction in functionality). Organizing the chip so that failsafe-checks occur during operation is certainly possible.
Again, check out the book for more details. The point is that these questions have been thought about and they are not insurmountable. The rate of defects generated from spurious environmental damage (e.g. cosmic rays) is low enough that it can be overcome with fairly straightforward engineering.