Molecule-sized Computers

Second US Team takes Step Toward Tiny Computer

Washington: Scientists said on Friday (19Nov99) they had created a molecule-sized device that may one day make cheap, superfast computers available, without relying on electricity.

The team, at Rice University in Houston and Yale University in New Haven, Connecticut, is the second group of companies to report that they have made "logic gates" - a kind of on-off switch for basic computer processes - out of a single molecule.

Logic gates are switches used to represent ones and zeroes, the binary language of digital computing.

Building one means a molecular computer - which researchers think would require far less power than current computers and may be able to hold vast amounts of data permanently - is one step closer, said chemistry professor James Tour of Rice, who worked on the study.

"Fifty percent of the job is done," he said in a statement. "The other fifty percent is memory."

Writing in Friday's (19Nov99) issue of the journal 'Science', the Yale/Rice team said their two-way switch, if it can be hooked up to a network of equally tiny and efficient materials, will be much faster than current silicon-based computers.

"It's about a million times smaller than a silicon device," Tour said in a telephone interview.

"For some applications they'll beat the pants off silicon," he added. "We are not suggesting that we are going to replace silicon... It really looks like we're going to have hybrid molecular-based and silicon-based computers within 5 to 10 years.

Engineering professor Mark Reed of Yale University noted that a lot of work has yet to be done.

"Although these are a host of engineering challenges to bring this to a manufacturable technology, this study demonstrates the principle and the fundamental limits of what can be done."

In July, a team at the University of California Los Angeles (UCLA) and at the Hewlett-Packard reported in the same journal that they had made a logic gate out of a single molecule.

"The biggest difference is that ours was reversible - theirs was irreversible," Tour said.

He said his team's molecular logic gate was far superior to a silicon-based one. "The amount that it turns on extra - it is a 1000 percent increase from off to on."

He said that it is not necessarily a problem with silicon-based devices, but it illustrates that molecules will be even better, and will be easy for engineers to work with. "It's a superior performance. People never expected it out of such a small molecule," he said.

And the low price can help transform the industry. Tour pointed out that making silicon chips is a fussy process. "Right now it costs about $2 billion to build a clean room," he said. "You have to find a way to make devices, lots of them, more cheaply."

-An article by Maggie Fox, in Sunday Times of India (21Nov99)