Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum coherence possible in incommensurate electronic systems

06.11.2006
Researchers at the University of Illinois at Urbana-Champaign have demonstrated that quantum coherence is possible in electronic systems that are incommensurate, thereby removing one obstacle in the development of quantum devices.

Electronic effects in thin films and at interfaces lie at the heart of modern solid-state electronic technology. As device dimensions shrink toward the nanoscale, quantum coherence and interference phenomena become increasingly important.

"At quantum dimensions, quantum mechanics says device components will couple together and act in a concerted manner, where everything affects everything else," said Tai-Chang Chiang, a professor of physics and a researcher at the university's Frederick Seitz Materials Research Laboratory. "Most scientists assume that electronic layers must be commensurate, so electrons will flow without being diverted or scattered."

In fact, however, most material interfaces are incommensurate as a result of differences in crystal sizes, symmetries or atomic spacing. Random scattering of electrons was thought to destroy quantum coherence in such systems at the nanoscale.

Now, by studying electron fringe structure in silver films on highly doped silicon substrates, Chiang and his research group show that even when electronic layers are incommensurate, they can still be coherent. The researchers report their findings in the Nov. 3 issue of the journal Science.

In work performed at the Synchrotron Radiation Center at the University of Wisconsin at Madison, the researchers grew atomically uniform silver films on highly doped n-type silicon substrates. Then they used a technique called angle-resolved photoemission to examine the fine-structured electronic fringes.

Although the silver films and silicon substrates are lattice mismatched and incommensurate, the wave functions are compatible and can be matched over the interface plane, Chiang said. The resulting state is coherent throughout the entire system.

The fringes the scientists recorded correspond to electronic states extending over the silver film as a quantum well and reaching into the silicon substrate as a quantum slope, with the two parts coherently coupled through an incommensurate interface structure.

"An important conclusion drawn from the present study is that coherent wave function engineering, as is traditionally carried out in lattice-matched epitaxial systems, is possible for incommensurate systems," the researchers wrote, "which can substantially broaden the selection of materials useful for coherent device architecture."

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>