Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017

The 'quantized magneto-electric effect' has been demonstrated for the first time in topological insulators at TU Wien, which is set to open up new and highly accurate methods of measurement

A light wave sent through empty space always oscillates in the same direction. However, certain materials can be used to rotate the direction in which the light is oscillating when placed in a magnetic field. This is known as a 'magneto-optical' effect.


In certain materials, light waves can change their direction of polarization.

Credit: TU Wien

After much speculation spanning a long period of time, one variant of this type of effect has now been demonstrated at TU Wien for the first time. Rather than switching the direction of the light wave continually, special materials called 'topological insulators' do so in quantum steps in clearly defined portions.

The extent of these quantum steps depends solely on fundamental physical parameters, such as the fine-structure constant. It may soon be possible to measure this constant even more accurately using optical techniques than is currently possible via other methods. The latest findings have now been revealed in the open-access journal 'Nature Communications'.

Topological insulators

"We have been working on materials that can change the direction of oscillation of light for some time now," explains Prof. Andrei Pimenov from the Institute of Solid State Physics at TU Wien. As a general rule, the effect depends on how thick the material is: the larger the distance to be travelled by the light in the material, the larger the angle of rotation.

However, this is not the case for the materials that Pimenov's team has now investigated more closely with the assistance of a research group from Würzburg. Their focus has been on 'topological insulators', for which the crucial parameter is the surface rather than the thickness.

Insulators on the inside, electricity can usually be conducted very effectively along the surface of a topological insulator. "Even when sending radiation through a topological insulator, the surface is what makes all the difference," says Pimenov. When light propagates in this material, the oscillation direction of the beam is turned by the surface of the material twice - once when it enters and again when it exits.

What is most remarkable here is that this rotation takes place in particular portions, in quantum steps, rather than being continuous. The interval between these points is not determined by the geometry or by properties of the material and is instead defined only by fundamental natural constants.

For example, they can be specified on the basis of the fine-structure constant, which is used to describe the strength of the electromagnetic interaction. This could open up the possibility of measuring natural constants with more precision than has previously been the case and may even lead to new measuring techniques being identified.

Increased measurement precision using special materials

The situation is similar for the quantum Hall effect, which is another quantum phenomenon observed in certain materials, in which case a particular variable (here electrical resistance) can rise only by certain amounts. The quantum Hall effect is currently used for high-precision measurements, with the official standard definition of electrical resistance being based on it. Back in 1985, the Nobel Prize in Physics was awarded for the discovery of the quantum Hall effect.

Topological materials have also already been the subject of a Nobel Prize victory - this time in 2016. It is expected that these latest results will also make it possible for materials with special topological characteristics (in this case topological insulators) to be used for specific technical applications.

Further information:

Prof. Andrei Pimenov
Institute for Solid State Physics
TU Wien
Wiedner Hauptstraße 8-10, 1040 Vienna
T: +43-1-58801-137 23
andrei.pimenov@tuwien.ac.at

Media Contact

Florian Aigner
florian.aigner@tuwien.ac.at
0043-155-801-41027

 @tuvienna

http://www.tuwien.ac.at/tu_vienna/ 

Florian Aigner | EurekAlert!

More articles from Physics and Astronomy:

nachricht Observations of nearby supernova and associated jet cocoon provide new insights on gamma-ray bursts
18.01.2019 | George Washington University

nachricht A new twist on a mesmerizing story
17.01.2019 | ETH Zurich Department of Physics

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: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Additive manufacturing reflects fundamental metallurgical principles to create materials

18.01.2019 | Materials Sciences

How molecules teeter in a laser field

18.01.2019 | Life Sciences

The cytoskeleton of neurons has been found to be involved in Alzheimer's disease

18.01.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>