David Kirkpatrick

May 25, 2010

A seven atom transistor

Via KurzweilAI.net — We are heading toward the terminus of physical computing components. Can’t get a whole lot smaller than seven atoms.

Quantum leap: World’s smallest transistor built with just 7 atoms
PhysOrg.com, May 24, 2010

The world’s smallest precision-built transistor — aquantum dot of just seven phosphorus atoms in a single silicon crystal — has been created by scientists from the UNSW Centre for Quantum Computer Technology and the University of Wisconsin-Madison.

At present, the length of a commercial transistor gate is about 40 nanometers (billionths of a metet). The new device has features about 10 times smaller at 4 nanometers.


Template of the quantum dot device showing a central hole where seven phosphorus atoms are incorporated
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February 27, 2010

Getting closer to a quantum computer

Another incremental step toward functional quantum computing. We don’t need quantum computing just yet, but we will.

The release:

UW-Madison physicists build basic quantum computing circuit

MADISON — Exerting delicate control over a pair of atoms within a mere seven-millionths-of-a-second window of opportunity, physicists at the University of Wisconsin-Madison created an atomic circuit that may help quantum computing become a reality.

Quantum computing represents a new paradigm in information processing that may complement classical computers. Much of the dizzying rate of increase in traditional computing power has come as transistors shrink and pack more tightly onto chips — a trend that cannot continue indefinitely.

“At some point in time you get to the limit where a single transistor that makes up an electronic circuit is one atom, and then you can no longer predict how the transistor will work with classical methods,” explains UW-Madison physics professor Mark Saffman. “You have to use the physics that describes atoms — quantum mechanics.”

At that point, he says, “you open up completely new possibilities for processing information. There are certain calculational problems… that can be solved exponentially faster on a quantum computer than on any foreseeable classical computer.”

With fellow physics professor Thad Walker, Saffman successfully used neutral atoms to create what is known as a controlled-NOT (CNOT) gate, a basic type of circuit that will be an essential element of any quantum computer. As described in the Jan. 8 issue of the journal Physical Review Letters, the work is the first demonstration of a quantum gate between two uncharged atoms.

The use of neutral atoms rather than charged ions or other materials distinguishes the achievement from previous work. “The current gold standard in experimental quantum computing has been set by trapped ions… People can run small programs now with up to eight ions in traps,” says Saffman.

However, to be useful for computing applications, systems must contain enough quantum bits, or qubits, to be capable of running long programs and handling more complex calculations. An ion-based system presents challenges for scaling up because ions are highly interactive with each other and their environment, making them difficult to control.

“Neutral atoms have the advantage that in their ground state they don’t talk to each other, so you can put more of them in a small region without having them interact with each other and cause problems,” Saffman says. “This is a step forward toward creating larger systems.”

The team used a combination of lasers, extreme cold (a fraction of a degree above absolute zero), and a powerful vacuum to immobilize two rubidium atoms within “optical traps.” They used another laser to excite the atoms to a high-energy state to create the CNOT quantum gate between the two atoms, also achieving a property called entanglement in which the states of the two atoms are linked such that measuring one provides information about the other.

Writing in the same journal issue, another team also entangled neutral atoms but without the CNOT gate. Creating the gate is advantageous because it allows more control over the states of the atoms, Saffman says, as well as demonstrating a fundamental aspect of an eventual quantum computer.

The Wisconsin group is now working toward arrays of up to 50 atoms to test the feasibility of scaling up their methods. They are also looking for ways to link qubits stored in atoms with qubits stored in light with an eye toward future communication applications, such as “quantum internets.”

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This work was funded by grants from the National Science Foundation, the Army Research Office and the Intelligence Advanced Research Projects Agency.

December 11, 2008

More on nanotech and public perception

Man, this study is producing a lot of press releases. I’ve blogged here and here so far, and now here’s more food for thought.

The release:

New studies reveal differing perceptions of nature-altering science

Religion and culture shape views of nanotechnology

Two new National Science Foundation (NSF)-sponsored research studies say public acceptance of the relatively new, nature-altering science of nanotechnology isn’t a foregone conclusion. Instead, the studies indicate continued concern.

Researchers at Yale University say that when people learn about this novel technology they become sharply divided along cultural lines, while a separate study led by researchers at the University of Wisconsin-Madison and Arizona State University says nanotechnology seems to be failing the moral litmus test of religion.

Federal entities are looking into safety and public acceptance issues surrounding nanotechnology because of its ability to alter matter on an atomic and molecular scale. The potential societal benefits of using nanotechnology to create new materials and devices for medicine, electronics and energy production could be huge. But the idea of creating them through molecular manipulation leaves some people apprehensive.

“Evidence shows that there is much room for improvement in efforts to communicate about the environmental, health, and safety impacts of nanotechnology,” said Robert E. O’Connor, NSF program manager for decision, risk and management sciences.

The Yale study, part of their Cultural Cognition Project, surveyed 1,500 Americans, the majority of whom were unfamiliar with nanotechnology. Researchers gave participants balanced information about its risks and benefits. Upon seeing it, study participants became highly divided on the technology’s safety compared to a group that was not shown the same information.

According to Dan Kahan, the Elizabeth K. Dollard Professor at Yale Law School and lead author of the study, people’s cultural values determined how they responded. “People who had more individualistic, pro-commerce values, tended to infer that nanotechnology is safe,” said Kahan. People more worried about economic inequality saw the same information as implying that nanotechnology is likely to be dangerous.

The finding is consistent with other Cultural Cognition Project studies that show people’s cultural values influence their perceptions of environmental and technological risks. Kahan notes, “When respondents learned about this new technology, they matched their views of its risks with previously held cultural values.”

A separate study conducted in the United States and Europe indicates that people with religious views see nanotechnology as less morally acceptable, compared with people who live in more secular societies.

According to the study, the United States and a few European countries where religion plays a larger role, notably Italy, Austria and Ireland see the potential of nanotechnology to alter living organisms or inspire synthetic life as less morally acceptable. In more secular European societies such as France and Germany, people are less likely to see nanotechnology as morally suspect.

“What we captured is nano-specific,” said Dietram Scheufele, University of Wisconsin-Madison professor of life sciences communication. “But it is also representative of a larger attitude toward science and technology. It raises a big question about what’s really going on in our public discourse where science and religion often clash.”

“Our findings show that the public no longer just turns to scientists for answers about the science, but also for answers about its social implications,” he said. “In other words, they want to know not only what can be done, but also what should be done. The more prepared scientists are to answer both questions, the more credible their societal leadership will be on issues like nanotechnology,” said Scheufele, who co-authored the study with Elizabeth Corley, School of Public Affairs at Arizona State.

According to O’Connor, both studies highlight the need for specific public education strategies that consider citizens’ values and predispositions. “Understanding that people make decisions about technology through the prisms of their personal values will be important to take into account if we are to accurately communicate the risks and benefits of innovations like nanotechnology to the public,” said O’Connor.

“There is still plenty of time to develop risk-communication strategies that make it possible for persons of diverse values to understand the best evidence on nanotechnology’s risks,” said Kahan. “The only mistake would be to assume that such communication strategies aren’t necessary.”

It’s estimated that nanotechnology will be a $3.1 trillion global industry by 2015. Both studies can be found in the Dec. 7, 2008, issue of the journal Nature Nanotechnology.

 

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August 14, 2008

Smaller electronics, larger hard drives

A new manufacturing approach in creating patterned templates should lead to improvements in hard drive technology and electronic devices. The key to the process is self-assembling materials called block copolymers combined with traditional lithography techniques.

From the link:

The block copolymers pattern the resulting array down to the molecular level, offering a precision unattainable by traditional lithography-based methods alone and even correcting irregularities in the underlying chemical pattern. Such nanoscale control also allows the researchers to create higher-resolution arrays capable of holding more information than those produced today.

In addition, the self-assembling block copolymers only need one-fourth as much patterning information as traditional materials to form the desired molecular architecture, making the process more efficient, Nealey says. “If you only have to pattern every fourth spot, you can write those patterns at a fraction of the time and expense,” he says.

In addition to shared intellectual contributions, the collaboration between the UW-Madison and Hitachi teams provided very clear objectives about creating a technology that is industrially viable. “This research addresses one of the most significant challenges to delivering patterned media — the mass production of patterned disks in high volume, at a reasonable cost,” says Richard New, director of research at Hitachi Global Storage Technologies. “The large potential gains in density offered by patterned media make it one of the most promising new technologies on the horizon for future hard disk drives.”

courtesy Paul Nealey

Researchers from the University of Wisconsin-Madison and Hitachi Global Storage Technologies have reported a way to improve the quality and resolution of patterned templates such as those used to manufacture hard drives and other data storage devices. When added to lithographically patterned surfaces such as those shown in the upper left panel of this composite image, specially designed materials called block copolymers self-assemble into structures, shown in the upper right panel, with improved quality and resolution over the original patterns. These structures can be used to make templates with nanoscale elements like the silicon pillars shown in the bottom panel, which may be useful for manufacturing higher capacity hard disk drives. Photo by: courtesy Paul Nealey

May 2, 2008

Nanotrees and nanomotors

From KurzweilAI.net, nanotrees are a new type of nanowire and Arizona State researchers have created the fastest nanomotor.

Spiraling nanotrees offer new twist on growth of nanowires
PhysOrg.com, May 1, 2008

University of Wisconsin-Madison researchers have discovered a new way of growing nanowires that leads to “nanopines”–elaborate pine-tree-shaped nanowires–caused by a “screw” dislocation, or defect, in their crystal structure.

Dislocations are fundamental to the growth and characteristics of all crystalline materials, but this is the first time they’ve been shown to aid the growthof one-dimensional nanostructures.

Engineering these dislocations may allow scientists to create more elaborate nanostructures, and to investigate the fundamental mechanical, thermal and electronic properties of dislocations in materials.

 
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Revving up the world’s fastest nanomotor
PhysOrg.com, May 1, 2008

Arizona State University researchers have developed a new generation of nanomotors with an average speed of 60 micrometers per second.


Tracks left by various types of speeding nanomotors (American Chemical Society)

Existing catalytic nanomotors–made with gold and platinum nanowires and fueled with hydrogen peroxide–have top speeds of about 10 micrometers per second.

The new design adds carbon nanotubes to the platinum (boosting the average speed) and spikes the hydrogenperoxide fuel with hydrazine to increase the nanomotor’s top speed to 200 nanometers per second.

 
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