Physicists have succeeded in fashioning a working transistor from a single phosphorus atom embedded in a silicon crystal.
(UNSW physicists have created a working transistor consisting of a single atom placed precisely in a silicon crystal.)
“Their approach is extremely powerful,” said Andreas Heinrich, a physicist at I.B.M. “This is at least a 10-year effort to make very tiny electrical wires and combine them with the placement of a phosphorus atom exactly where they want them.”
Dr. Heinrich said the research was a significant step toward making a functioning quantum computing system. However, whether quantum computing will ever be harnessed for useful tasks remains uncertain, and the researchers noted that their work demonstrated the fundamental limits that today’s computers would be able to shrink to.
“It shows that Moore’s Law can be scaled toward atomic scales in silicon,” said Gerhard Klimeck, a professor of electrical and computer engineering at Purdue and leader of the project there. Moore’s Law refers to technology improvements by the semiconductor industry that have doubled the number of transistors on a silicon chip roughly every 18 months for the past half-century. That has led to accelerating increases in performance and declining prices. “The technologies for classical computing can survive to the atomic scale,” Dr. Klimeck said.
The scientists placed the single phosphorus atom using a device known as a scanning tunneling microscope. They used it to essentially scrape trenches and a small cavity on a surface of silicon covered with a layer of hydrogen atoms. Phosphine gas was then used to deposit a phosphorus atom at a precise location, which was then encased in further layers of silicon atoms.
The first time I ever heard of this idea was in Robert Heinlein's 1951 novel Between Planets.
"It is theoretically possible to have a matrix in which each individual molecule has a meaning - as they do in the memory cells of your brain. If we had such subtlety, we could wrap your Encyclopedia Britannica into the head of a pin - it would be the head of that pin..."
(Read more about Heinlein's molecule matrix)