Single-Atom Transistor Is End of Moore's Law; May Be Beginning of Quantum Computing

The smallest transistor ever built -- in fact, the smallest transistor that can be built -- has been created using a single phosphorus atom by an international team of researchers at the University of New South Wales, Purdue University and the University of Melbourne.

The single-atom device was described Sunday (Feb. 19) in a paper in the journal Nature Nanotechnology.
Michelle Simmons, group leader and director of the ARC Centre for Quantum Computation and Communication at the University of New South Wales, says the development is less about improving current technology than building future tech.
"This is a beautiful demonstration of controlling matter at the atomic scale to make a real device," Simmons says. "Fifty years ago when the first transistor was developed, no one could have predicted the role that computers would play in our society today. As we transition to atomic-scale devices, we are now entering a new paradigm where quantum mechanics promises a similar technological disruption. It is the promise of this future technology that makes this present development so exciting."
The same research team announced in January that it had developed a wire of phosphorus and silicon -- just one atom tall and four atoms wide -- that behaved like copper wire.
Simulations of the atomic transistor to model its behavior were conducted at Purdue using nanoHUB technology, an online community resource site for researchers in computational nanotechnology.
Gerhard Klimeck, who directed the Purdue group that ran the simulations, says this is an important development because it shows how small electronic components can be engineered.
"To me, this is the physical limit of Moore's Law," Klimeck says. "We can't make it smaller than this."
Although definitions can vary, simply stated Moore's Law holds that the number of transistors that can be placed on a processor will double approximately every 18 months. The latest Intel chip, the "Sandy Bridge," uses a manufacturing process to place 2.3 billion transistors 32 nanometers apart. A single phosphorus atom, by comparison, is just 0.1 nanometers across, which would significantly reduce the size of processors made using this technique, although it may be many years before single-atom processors actually are manufactured.
The single-atom transistor does have one serious limitation: It must be kept very cold, at least as cold as liquid nitrogen, or minus 391 degrees Fahrenheit (minus 196 Celsius).
"The atom sits in a well or channel, and for it to operate as a transistor the electrons must stay in that channel," Klimeck says. "At higher temperatures, the electrons move more and go outside of the channel. For this atom to act like a metal you have to contain the electrons to the channel.
"If someone develops a technique to contain the electrons, this technique could be used to build a computer that would work at room temperature. But this is a fundamental question for this technology."
Complete article in here
Journal Reference:

1. Martin Fuechsle, Jill A. Miwa, Suddhasatta Mahapatra, Hoon Ryu, Sunhee Lee, Oliver Warschkow, Lloyd C. L. Hollenberg, Gerhard Klimeck, Michelle Y. Simmons. A single-atom transistor. Nature Nanotechnology, 2012; DOI: 10.1038/nnano.2012.21