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Dead medium: The Molecular Abacus
From: eyebrown@interpath.com (Stephen P. Brown)
Source(s): SCIENCE NEWS Dec. 7, 1996 Vol 150, No 23, page 363

"Molecular Abacus Counts on Buckyballs

"One of the world's oldest counting machines is now also one of the newest. Scientists at the IBM Zurich Research Laboratory have constructed a tiny abacus that substitutes carbon-60 buckyballs for the traditional beads. This nanoscale abacus is the first room- temperature device that can store and manipulate numbers at the molecular level.

"The buckyballs rest in orderly rows along shallow steps cut into a piece of copper. The tip of a scanning tunneling microscope (STM) pushes the molecules along the steps, just as a person's finger would slide the beads of an abacus back and forth on a wire. Some of the underlying copper atoms move too, forming tiny 'kinks' that fix the buckyballs in their new positions. The scientists report their achievement in the Nov. 11 APPLIED PHYSICS LETTERS.

"The inspiration to make a nanoscale abacus came not only from previous work that moved single atoms with an STM, but also from a trip to Japan, said project leader James K. Gimzewski. 'I saw that in the Tokyo railway station, many of the ticket sellers actually use abacuses.' From that observation, Gimzewski and his group decided to 'start from the bottom up and make a working demo of an abacus, using single molecules.'

"Right now, only one buckyball can be moved at a time, a process Gimzewski describes as 'moving grains of sand with Mount Fuji.' Faster STM tips and designs with many probes working in parallel could improve the speed of the device."

(((The mental image of future hyper-super microprocessors doing the math stuff with teraflop nano-abacuses is a concept irresistibly elegant and wonderful to me -- SPB)))

Stephen P. Brown (eyebrown@interpath.com)