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the molecular-sized computer, however, that has captured the attention
of the world, or at least The New York Times and other hot media
(of Heath, Vanity Fair rhapsodized in its end-of-the-millennium
1999 Hall of Fame: "Like William Blake, he spies the world in a
grain of sand"). The idea emerged after Heath was recruited by UCLA
chemist Stan Williams to help Hewlett-Packard launch a basic research
division. While at HP, Heath and Williams met Phil Keukes, an HP
physicist, who introduced them to Teramac, an HP computer capable
of astounding performance while being as riddled with defective
circuits as Swiss cheese is with holes. This made Teramac exceedingly
relevant to Heath's dreams of synthesizing computers from the bottom
up. "If you're going to design a computer by chemical synthesis,"
says Heath, "you're inevitably going to have plenty of defects.
It's going to be far from perfect. But Teramac had a quarter-of-a-million
defects in it and it still did a trillion operations per second.
And these were hardware defects, not software bugs. If a Pentium
even has one, it's trash. And so the very fact that this worked
suggested that we ought to take some time and learn about this machine."
Keukes and Williams, along with HP's Gregory Snider, spent the next
two years studying Teramac and writing a paper for the prestigious
journal Science on a computer architecture that would be resistant
to defects and that could be synthesized using the techniques of
nanotechnology. The essence of their plan was to grow an ordered
crystal of redundant wires and switches, locate the defects and
then, in effect, download the logical architecture of the computer
in such a way that it wired itself around those defects into working
circuits. The Science article came out in June 1998 and "made a
splash," says Heath. "I think broken computers resonate with people,
and here was one that was broken that actually worked."
and his group, along with Professor of Chemistry Fraser Stoddart's
group, then spent the next year trying to synthesize their thinking
machine. While Heath had thought his quantum dots might be useful,
that turned out not to be the case. Instead they have been working
on a device built of tiny quantum wires and switches made from Stoddart's
molecules that can be turned on and off through quantum mechanical
processes. They published their first example of such a device last
summer, which was when they graced the front page of The New York
Times. "It was amazing," says Heath. "I thought we did something
pretty significant, but I didn't think it was that significant."
the 1999 version of the computer was only what Heath calls a demonstration
of architecture. While they could set their molecular switches on
or off, they could only switch them once. So Heath and his colleagues
have been working again with Stoddart's and Professor of Chemistry
Fred Wudl's '64, Ph.D. '67 groups to concoct molecular switches
that can be switched repeatedly, of which they now have four. "You
can switch two electronically," says Heath, "one chemically and
one optically. But they're all based on very similar architectures.
Molecules just do things like that."