Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Find Asymmetry in Topological Insulators

14.08.2013
Surprising findings bolster case for energy efficient quantum computer

New research shows that a class of materials being eyed for the next generation of computers behaves asymmetrically at the sub-atomic level. This research is a key step toward understanding the topological insulators that may have the potential to be the building blocks of a super-fast quantum computer that could run on almost no electricity.

Scientists from the Energy Department’s National Renewable Energy Laboratory contributed first-principles calculations and co-authored the paper “Mapping the Orbital Wavefunction of the Surface States in 3-D Topological Insulators,” which appears in the current issue of Nature Physics. A topological insulator is a material that behaves as an insulator in its interior but whose surface contains conducting states.

In the paper, researchers explain how the materials act differently above and below the Dirac point and how the orbital and spin texture of topological insulator states switched exactly at the Dirac point. The Dirac point refers to the place where two conical forms – one representing energy, the other momentum – come together at a point. In the case of topological insulators, the orbital and spin textures of the sub-atomic particles switch precisely at the Dirac point. The phenomenon occurs because of the relationship between electrons and their holes in a semiconductor.

This research is a key step toward understanding the topological insulators like bismuth selenide (Bi2Se3), bismuth telluride (Bi2Te3), antimony telluride (Sb2Te3), and mercury telluride (HgTe) that may have the potential to be the building blocks of a quantum computer, a machine with the potential of loading the information from a data center into the space of a laptop and processing data much faster than today's best supercomputers.

“The energy efficiency should be much better,” said NREL Scientist Jun-Wei Luo, one of the co-authors. Instead of being confined to the on-and-off switches of the binary code, a quantum computer will act more like the human brain, seeing something but imagining much more, he said. “This is entirely different technology.”

Topological Insulators are of great interest currently for their potential to use their exotic properties to transmit information on electron spins with virtually no expenditure of electricity, said Luo. NREL’s Xiuwen Zhang is another co-author as are scientists from University of Colorado, Rutgers University, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, and the Colorado School of Mines. Luo and Zhang work in NREL’s Center for Inverse Design, one of 46 Energy Frontier Research Centers established around the nation by the Energy Department’s Office of Science in 2009 to accelerate basic research on energy.

The finding of orbital texture switch at Dirac point implies the novel backwards spin texture -- right-handed instead of left-handed, in the short-hand of physicists -- comes from the coupling of spin texture to the orbital texture for the conserved quantity is total angular momentum of the wave function, not spin. The new findings, supported partly by observations taken at the Advanced Light Source at Lawrence Berkeley National Laboratory, were surprising and bolster the potential of the topological insulators.

“In this paper, we computed and measured the profile of the topological states and found that the orbital texture of topological states switches from tangential to radial across the Dirac point,” Zhang said. Equally surprising, they found that phenomenon wasn’t a function of a unique material, but was common to all topological insulators.

The topological insulators probably won’t be practical for solar cells, because at the surface they contain no band gap. A band gap – the gap between when a material is in a conducting state and an inert state – is essential for solar cells to free photons and have them turn into energy carrying electrons.

But the topological insulators could be very useful for other kinds of electronics-spintronics. The electrons of topological insulators will self-polarize at opposite device edges. “We usually drive the electron in a particular direction to spatially separate the spin-up and spin-down electrons, but this exotic property suggests that electrons as a group don’t have to move,” Luo said. “The initial idea is we don’t need any current to polarize the electron spins. We may be able to develop a spin quantum computer and spin quantum computations.”

In theory, an entire data center could operate with virtually no electricity. “That’s probably more in theory than reality,” Luo said, noting that other components of the center likely would still need electricity. “But it would be far more energy efficient.” And the steep drop in electricity would also mean a steep drop in the number of coolers and fans needed to cool things down.

Luo cautioned that this is still basic science. The findings may have limited application to renewable energy, but Luo noted that another of NREL’s key missions is energy efficiency.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by the Alliance for Sustainable Energy, LLC.

David Glickson | EurekAlert!
Further information:
http://www.nrel.gov

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>