Researchers say they've made a key step toward the next age of computing, making the world's smallest transistor.
The researchers, based at the University of New South Wales and University of Wisconsin-Madison, have constructed the tiny electronic component through the manipulation of a small number of atoms.
The breakthrough, which appears in the journal Nature Nanotechnology, is seen as another step towards the world's first quantum computer.
Moore's Law, which has driven technological change at a breakneck pace for decades, states that the number of transistors on a microprocessor doubles every year or two.
But Professor Andrew White of the University of Queensland, says that progress is beginning to slow.
"For the last couple of years you've had one or two gigahertz chips and they're no longer talking about speed, they're talking about things like multiple cores and things like that," says White. "That's because it's getting harder and harder to make the wires smaller and it's getting harder and harder to double the power every 18 months.
Pushing the limit
White says the eventual limit to Moore's Law will be that the wires will eventually be one atom each thick.
"You have no more increase of power at that point if you're stuck with the classical computing model," he says.
That's where quantum computing comes in; if scientists can get computer processors to work on an atomic scale.
The technology to move atoms around on a surface has been around for decades, but no one's managed to do it with enough precision to make a device that can process electronic input.
"When you get down to the very small single atom level you can actually start to control those quantum states and build a whole computer based on the quantum principles," says Professor Michelle Simmons of the University of New South Wales.
Her team have succeeded in taking a silicone crystal and replacing seven of its atoms with phosphorous atoms.
"I guess the critical thing that we've done is being able to connect from the outside world to those atoms. You actually have a functioning electronic device," she says.
"It's the world's smallest component where we've actually put the atoms exactly where we want them."
As scientists around the world race to develop the first quantum computer, Simmons is focussing on silicon as a basis for her experiments because it's used in current computer technology.
White has also been trying to make a quantum computer, but he's using single particles of light.
"No one really knows which technique will work," says White. "We really don't know what will be the answer and it probably will be some hybrid of them, but we don't know yet."
Having worked out a way to make individual components out of seven atoms, Simmons and her team are working on reducing it to one atom. If they achieve that they'll start building a quantum computer.
"For us probably it's about another five to ten years away," she says. "We're ruthlessly going ahead to try and make the next stage of the quantum computer."
So the question is: When can I have a quantum computer on my desktop?
"Ah now that's a very interesting question because I think at the beginning the quantum computers are probably going to be held by a few people where you can access them, like a mainframe system," says Simmons.
"They have to be kept cold and operate at very low temperatures to maintain the quantum state. So it's not going to be something that I see in the next 20 years that you would have one on your desk."