Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum computing breakthrough arises from unknown molecule

01.07.2008
The odd behavior of a molecule in an experimental silicon computer chip has led to a discovery that opens the door to quantum computing in semiconductors.

In a Nature Physics journal paper currently online, the researchers describe how they have created a new, hybrid molecule in which its quantum state can be intentionally manipulated - a required step in the building of quantum computers.

"Up to now large-scale quantum computing has been a dream," says Gerhard Klimeck, professor of electrical and computer engineering at Purdue University and associate director for technology for the national Network for Computational Nanotechnology.

"This development may not bring us a quantum computer 10 years faster, but our dreams about these machines are now more realistic."

The workings of traditional computers haven't changed since they were room-sized behemoths 50 years ago; they still use bits of information, 1s and 0s, to store and process information. Quantum computers would harness the strange behaviors found in quantum physics to create computers that would carry information using quantum bits, or qubits. Computers would be able to process exponentially more information.

If a traditional computer were given the task of looking up a person's phone number in a telephone book, it would look at each name in order until it found the right number. Computers can do this much faster than people, but it is still a sequential task. A quantum computer, however, could look at all of the names in the telephone book simultaneously.

Quantum computers also could take advantage of the bizarre behaviors of quantum mechanics - some of which are counterintuitive even to physicists - in ways that are hard to fathom. For example, two quantum computers could, in concept, communicate instantaneously across any distance imaginable, even across solar systems.

Albert Einstein, in a letter to Erwin Schrödinger in the 1930s, wrote that in a quantum state a keg of gunpowder would have both exploded and unexploded molecules within it (a notion that led Schrödinger to create his famous cat-in-a-box thought experiment).

This "neither here nor there" quantum state is what can be controlled in this new molecule simply by altering the voltage of the transistor.

Until now, the challenge had been to create a computer semiconductor in which the quantum state could be controlled, creating a qubit.

"If you want to build a quantum computer you have to be able to control the occupancy of the quantum states," Klimeck says. "We can control the location of the electron in this artificial atom and, therefore, control the quantum state with an externally applied electrical field."

The discovery began when Sven Rogge and his colleagues at Delft University of Technology in the Netherlands were experimenting with nano-scale transistors that show the effects of unintentional impurities, or dopants. The researchers found properties in the current-voltage characteristics of the transistor that indicated electrons were being transported by a single atom, but it was unclear what impurity was causing this effect.

Physicist Lloyd Hollenberg and colleagues at the University of Melbourne in Australia were able to construct a theoretical silicon-based quantum computer chip based on the concept of using an individual impurity.

"The team found that the measurements only made sense if the molecule was considered to be made of two parts," Hollenberg says. "One end comprised the arsenic atom embedded in the silicon, while the 'artificial' end of the molecule forms near the silicon surface of the transistor. A single electron was spread across both ends.

"What is strange about the 'surface' end of the molecule is that it occurs as an artifact when we apply electrical current across the transistor and hence can be considered 'manmade.' We have no equivalent form existing naturally in the world around us."

Klimeck, along with graduate student Rajib Rahman, developed an updated version of the nano-electronics modeling program NEMO 3-D to simulate the material at the size of 3 million atoms.

"We needed to model such a large number of atoms to see the new, extended quantum characteristics," Klimeck says.

The simulation showed that the new molecule is a hybrid, with the naturally occurring arsenic at one end in a normal spherical shape and a new, artificial atom at the other end in a flattened, 2-D shape. By controlling the voltage, the researchers found that they could make an electron go to either end of the molecule or exist in an intermediate, quantum, state.

This model was then made into an image by David Ebert, a professor of electrical and computer engineering at Purdue, and graduate student Insoo Woo.

Delft's Rogge says the discovery also highlights the current capabilities of designing electronic machines.

"Our experiment made us realize that industrial electronic devices have now reached the level where we can study and manipulate the state of a single atom," Rogge says. "This is the ultimate limit, you can not get smaller than that."

Writer: Steve Tally, (765) 494-9809, tally@purdue.edu
Sources: Gerhard Klimeck, (765) 494-9212, gekco@purdue.edu
Sven Rogge, +31 (0) 15 278 24 95, s.rogge@tudelft.nl
Lloyd Hollenberg, +61 3 8344 4210, lloydch@unimelb.edu.au
Purdue News Service: (765) 494-2096; purduenews@purdue.edu

Steve Tally | EurekAlert!
Further information:
http://www.purdue.edu

More articles from Health and Medicine:

nachricht Researchers release the brakes on the immune system
18.10.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Shallow soils promote savannas in South America

20.10.2017 | Earth Sciences

How Obesity Promotes Breast Cancer

20.10.2017 | Life Sciences

How the smallest bacterial pathogens outwit host immune defences by stealth mechanisms

20.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>