Nanocomputers

Nanoelectronics, electronics made of tiny components, took a leap forward this week with the announcements of the first molecule-sized transistors and logic gates.
These basic devices are an important step towards developing tiny computers that will be faster, cheaper and more powerful than anything available with today's technology.
Ever since Nobel Prize winner Richard Feynman suggested that people could build machines the size of atoms, nanotechnology has been on the minds of scientists and sci-fi fans alike.
Nanophiles envision a futuristic world filled with teeny robots that can build diamonds out of the carbon atoms in a sheet of paper, or fly through your body scraping cholesterol off of your artery walls.
These and other spectacular promises have yet to materialize, but two articles published in this week's issue of Science magazine report significant advances in the sub-field of nanoelectronics.
First, a group at Lucent's Bell Labs built a Field-Effect Transistor (FET) from a single molecule.
"FETs are the powerhouse of modern electronics," said team member Jan Hendrik Schön. Creating a molecular-sized FET is the first step in building a nanocomputer.
The team's transistor is an organic molecule about 50,000 times smaller than the width of a human hair. It has the added benefit of bonding to plastics and other synthetic materials, something present-day silicon technologies cannot do.
Schön said this special ability might allow computer circuits to become integrated into credit cards and clothing. The fact that the molecule can be stored easily in a liquid solution also opens up the possibility of using ink-jet type technology to "print" processors on sheets of plastic.
The second paper describes how researchers based at Harvard University made semiconducting nanowires that assembled themselves into simple circuits.
"Self assembly is a concept that's been present in biology for billions of years," says Charles Lieber, the leader of the Harvard team.
To apply the self-assembly concept to their DNA-sized nanowires, the researchers grew the wires in a liquid and then squirted it over an array of electrical contacts. The wires attach to specialized glues on the contacts, arranging themselves into complex grids whose intersections behave like miniature FETs. By depositing layers of glues, liquids, and wires, the team was able to create a nanocircuit that could perform basic addition operations.
"I think that eventually you will be able create structures that are so integrated that they go right off the existing roadmap (of existing technology)," Leiber says. But Leiber also sees some long-term potential in quantum computing --computers based on the bizarre laws of quantum mechanics.
"When you make things very small," he explained, "the quantum mechanical features show up."
The nanowires used by the Harvard team are small enough to have quantum mechanical properties. "We don't know how to manipulate those properties very well, but they're there," he said. And with extensive research they might be able to use the wires in a future quantum computer.
"These are impressive achievements," says Ralph Merkle, a principal fellow at Zyvex, the world's first molecular nanotechnology company. Merkle believes that the compact size and enormous processing potential of these technologies might change the way we interact with computers.
"One of the things that's quite remarkable is the extent to which computers have become a vital part of our everyday lives when essentially they are just a box, a screen, and a keyboard," he said.
Molecular processors, he explained, could allow computers to see, hear and interact with humans much more directly. "Rather than us sitting down in front of a shrine, called a monitor, computers will do things in our world," he said.
But do we really need to develop technology so powerful that it can cram all present-day computer power into a space no larger than a sugar cube?
Merkle seems to think so. "Every time people say 'Gosh, what do we need more computer power for?' somebody comes up with a new application. Just take a look at Windows: we're going to need these molecular computers to run Windows 2015."