Quantum leap: World's smallest transistor built with just 7 atoms

May 24, 2010 By Bob Beale
An image of the template of the quantum dot device showing a central hole where seven phosphorus atoms are incorporated. Running diagonally from top left to bottom right are the two electronic leads to connect to the dot.

(PhysOrg.com) -- Scientists have literally taken a leap into a new era of computing power by making the world's smallest precision-built transistor - a "quantum dot" of just seven atoms in a single silicon crystal. Despite its incredibly tiny size - a mere four billionths of a metre long - the quantum dot is a functioning electronic device, the world's first created deliberately by placing individual atoms.

It can be used to regulate and control electrical current flow like a commercial transistor but it represents a key step into a new age of atomic-scale miniaturisation and super-fast, super-powerful computers.

The discovery is reported today in the journal Nature Nanotechnology by a team from the UNSW Centre for Quantum Computer Technology (CQCT) and the University of Wisconsin-Madison.

"The significance of this achievement is that we are not just moving atoms around or looking at them through a microscope," says co-author Professor Michelle Simmons, Director of the CQCT, an Australian Research Council Centre of Excellence. "We are manipulating individual atoms and placing them with atomic precision, in order to make a working electronic device.

"The Australian team has been able to fabricate an electronic device entirely out of crystalline silicon where we have replaced just seven individual silicon atoms with phosphorus atoms. That is amazing exactness.

"This is a huge technological achievement and it is a critical step to demonstrating that it is possible to build the ultimate computer - a quantum computer in silicon."

The technology for placing individual atoms on a surface, the scanning tunnelling microscope, has existed for two decades. But until now nobody has been able to use it to make atomic-precision devices capable of processing electronic inputs from the macroscopic world.

"We are testing the limits of how small an electronic device can be," Professor Simmons says. "Australia's first computer was commissioned in 1949. It took up an entire room and you could hold its components in your hands. Today you can carry a computer around in your hand and many of its components are more than 1000 times smaller than the width of a human hair.

"Now we have just demonstrated the world's first electronic device in silicon systematically created on the scale of individual atoms. This is highly significant not just for computer buffs but for all Australians. For 50 years, this process of miniaturization has been fundamental in driving productivity growth across the global economy. We have shown that this process can continue."

The team's primary goal is to create a quantum computer in silicon - an area where Australia has a unique collection of researchers and an international lead. This new device demonstrates that the technologies to enable fabrication and measurement at the atomic scale have begun to arrive.

At present, the length of a commercial transistor gate - which allows the transistor to act as an amplifier or switch for an electrical current - is about 40 nanometres (billionths of a metre). The CQCT team is now making devices with features about 10 times smaller at 4 nanometres.

It is 20 years since the world's smallest logo was made by Don Eigler and Erhard Schweizer at IBM's Almaden Research Center in San Jose, California, Professor Simmons notes. They used a scanning tunnelling microscope to place 35 xenon atoms individually on a nickel surface to write the letters 'IBM'.

They ended their paper in the journal Nature with a comment that 'the possibilities for perhaps the ultimate in device miniaturization are evident', but added several notes of caution and concluded tentatively that 'the prospect of atomic-scale logic circuits and other devices is a little less remote'.

"Well, what seemed remote then is now a reality," Professor Simmons says. "We have found a way to use that microscope not simply to observe or manipulate atoms but to purposefully build with atomic precision a device with just seven atoms and it works in a real environment."

Explore further: A tool for measuring atomic properties at the quantum limit

More information: www.nature.com/nnano/index.html

Provided by University of New South Wales

4.7 /5 (52 votes)

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KronosDeret
5 / 5 (5) May 24, 2010
and thats two more points for Australia, singularity here we come :)
nuge
5 / 5 (2) May 24, 2010
Towards a quantum computer? How can this store a qubit? From the article it sounds like its just a really small conventional transistor, encoding a regular bit. Or was there some detail I missed?
LivaN
5 / 5 (3) May 24, 2010
It's mind blowing to realise that there are people who can build stuff out of atoms...
mauro48it
3.6 / 5 (5) May 24, 2010
The next challenge is to find a technology able to assemble such a computer before the extinction of the human race.
Noumenon
4.8 / 5 (47) May 24, 2010
Towards a quantum computer? How can this store a qubit? From the article it sounds like its just a really small conventional transistor, encoding a regular bit. Or was there some detail I missed?


They didn't say it would store a qubit. The components used in a proposed quantum computer would have to be small enough to operate within qm realm, I.e. entanglement.
LivaN
4 / 5 (4) May 24, 2010
The next challenge is to find a technology able to assemble such a computer before the extinction of the human race.


I think you underestimate the rate at which innovations develope. Far underestimate it.
Birthmark
4.2 / 5 (5) May 24, 2010
This is mind-boggling, I mean it's amazing to think that we went from a computer that filled a room that can now fit in your pocket...I'm dying to see 10 years from now in 2020 when it will be common place to see quantum computing in everything around us; phones, computers, everything! I'm so excited for the singularity :)
Noumenon
4.9 / 5 (45) May 24, 2010
Feynman would have been proud.
pauljpease
5 / 5 (3) May 24, 2010
It's mind blowing to realise that there are people who can build stuff out of atoms...


I think it's even more mind blowing that people's bodies build themselves out of atoms!
Bob_B
2.5 / 5 (2) May 24, 2010
@pauljpease
And that water (of which we are 97%) is elevated up to 2 meters above the ground inside the body by just that 3% of atoms.

Water does work wonders.
purringrumba
not rated yet May 24, 2010
Feynman would have been proud.


Yes! And we are running out of what used to be 'plenty of' room.
de_la_meu
1 / 5 (1) May 24, 2010
@pauljpease
And that water (of which we are 97%) is elevated up to 2 meters above the ground inside the body by just that 3% of atoms.

Water does work wonders.

I'm pretty sure that water is also made of atoms. And body water percentage is around 60 in terms of weight.
Vaughn
not rated yet May 24, 2010
These folks really need to hook up with the folks working on DNA-based pattern assembly. It may cause a 'scaling' up in size, but it's the only likely means of fabricating large scale circuits efficiently. Might even suggest a switch to a graphene substrate at the same time :)
magpies
not rated yet May 24, 2010
So what happens if this device gets "bumped"? Are the bonds between the atoms really strong?
RobertKarlStonjek
not rated yet May 24, 2010
If RadioShack sold these transistors at 1c for a million of them, they could fit around a quintillion dollars worth in a standard component tray (one quintillion=one million million million or 10^18, assuming around one pound of components on the tray)...and don't think you can stash a few in your pocket and sneak out of the shop!!...
Parsec
not rated yet May 25, 2010
And if they cost 2c to make a million of them, they could run a deficit close to the national debt in seconds!
thematrix606
not rated yet May 28, 2010
The billion dollar question is: If you build it, will it run Crysis?

Yes: go to finish, acquire 1 billion dollars.
No: go back to start, all your base are belong to us!
Quantum_Conundrum
not rated yet May 29, 2010
I think you underestimate the rate at which innovations develope. Far underestimate it.


Agreed, seeing as how this is silicon and essentially the same core technology as existing computers, it's likely to be on the shelf in a year or two...

And just to put this in perspective, if the transistor is 1/10th as wide, then that means you can theoretically put 100 times as many transistors in the same 2 dimensional area.

The billion dollar question is: If you build it, will it run Crysis?

Yes: go to finish, acquire 1 billion dollars.
No: go back to start, all your base are belong to us!


It would take centuries for a game development company to program a video game that uses a 4nm architecture's entire potential by design...

You could still bog it down with intentional memory leaks or something, but "by design" would take a game or a simulation far, far more complex than anything even remotely on the market today.
Quantum_Conundrum
not rated yet May 29, 2010
They will have "processor ports" on motherboards which will work much like video cards do now.

You'll be able to just plug in a card with like 256 * 4nm processors and a terrabyte of ram built in, and your motherboard will have like 4-8 ports crammed in the space where the entire 4 core or 8 core processor is now...
PinkElephant
not rated yet May 29, 2010
It's a loooong way from painstakingly assembling a single transistor by nudging individual atoms around with an atomic force microscope tip, to manufacturing of VLSI circuits containing billions of such transistors, with mere seconds of assembly time per processor.

Then there's the issue of noise. With a transistor so small, you're going to have all sorts of spurious signals getting through, due to just thermal noise. The operating voltage (from source to sink) across such a transistor would have to be incredibly tiny, to avoid causing a breakdown and/or electron tunneling currents. Tiny voltages again run up against over-threshold noise issues.

And then there are thermal problems with packing so many tiny transistors close together, and trying to deliver current to all of them. The thinner a wire, the greater its resistance. And dissipating heat is already a problem with 32 nm manufacturing nodes; at 4 nm it's absolutly insurmountable with current state of the art methods.
Quantum_Conundrum
not rated yet May 30, 2010
Pink Elephant:

Thermal problems can be handled by "rotating" the processors. I.E. have some in a "sleep mode" while others work, and then as temperatures rise swap them in and out.