Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Breakthrough in light sources for new quantum technology

29.08.2014

Electronic circuits are based on electrons, but one of the most promising technologies for future quantum circuits are photonic circuits, i.e. circuits based on light (photons) instead of electrons.

First, it is necessary to be able to create a stream of single photons and control their direction. Researchers around the world have made all sorts of attempts to achieve this control, but now scientists at the Niels Bohr Institute have succeeded in creating a steady stream of photons emitted one at a time and in a particular direction. The breakthrough has been published in the scientific journal Physical Review Letters.

Single-photon Cannon

This is an illustration of the single-photon cannon. A quantum dot (illustrated with the yellow symbol) emits one photon (red wave packet) at a time. The quantum dot is embedded in a photonic-crystal structure, which is obtained by etching holes (black circles) in a semiconducting material (light grey). Due to the holes, the photons are not emitted in all directions, but only along the channel where there are no holes. Only 1.6 percent of the emitted photons will be emitted in other directions (illustrated by the upward moving photon) and is thus lost, while 98.4 percent are emitted in the desired direction.

Credit: Illustration: Marta Arcari, Niels Bohr Institute

Photons and electrons behave very differently at the quantum level. A quantum is the smallest unit in the atomic world and photons are the basic units of light and electrons of electrical current. Electrons are so-called fermions and can easily flow individually, while photons are bosons that prefer to clump together. But because information for quantum communication based on photonics lies in the individual photon, it is necessary to be able to send them one at a time.

"So you need to emit the photons from a fermionic system and we do this by creating an extremely strong interaction between light and matter," explains Peter Lodahl, Professor and head of the research group Quantum Photonics at the Niels Bohr Institute at the University of Copenhagen.

Photon canon

The researchers have developed a kind of single-photon cannon integrated on an optical chip. The optical chip consists of an extremely small photonic crystal that is 10 microns wide (1 micron is a thousandth of a millimeter) and 160 nanometers thick (1 nanometer is a thousandth of micron.) Embedded in the centre of the chip is a light source, a so-called quantum dot.

"What we then do is shine laser light on the quantum dot, where there are atoms with electrons in orbit around the nucleus. The laser light excites the electrons, which then jump from one orbit to another and thereby emit one photon at a time. Normally, light is scattered in all directions, but we have designed the photonic chip so that all of the photons are sent through only one channel," explains Søren Stobbe, Associate Professor of the Quantum Photonic research group at the Niels Bohr Institute.

Peter Lodahl and Søren Stobbe explain that it not only works, but also that it is extremely effective. "We can control the photons and send them in the direction we want with a 98.4 percent success rate. This is ultimate control over the interaction between matter and light and has amazing potential. Such a single-photon cannon has long been sought after in the research field and opens up fascinating new opportunities for fundamental experiments and new technologies," they explain.

The two researchers are in the process of patenting several parts of their work, with a specific goal of developing a prototype high-efficiency single-photon source, which could be used for encryption or for calculations of complex quantum mechanical problems and in general, is an essential building block for future quantum technologies. It is expected that the future's quantum technology will lead to new ways to code unbreakable information and to carry out complex parallel calculations.

###

For more information contact:

Peter Lodahl, Professor and head of the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen. Tel: +45 2056-5303, lodahl@nbi.ku.dk

Søren Stobbe, Associate Professor in the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen. Tel: +45 6065-6769, stobbe@nbi.ku.dk

Gertie Skaarup | Eurek Alert!

Further reports about: Photonic Quantum electrons fermions photons technologies

More articles from Physics and Astronomy:

nachricht Successful Boron-Doping of Graphene Nanoribbon
27.08.2015 | Universität Basel

nachricht New theory leads to radiationless revolution
27.08.2015 | Australian National University

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: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

Im Focus: Self-healing landscape: landslides after earthquake

In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.

These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...

Im Focus: FIC Proteins Send Bacteria Into Hibernation

Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.

For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...

Im Focus: Fraunhofer IPA develops prototype of intelligent care cart

It comes when called, bringing care utensils with it and recording how they are used: Fraunhofer IPA is developing an intelligent care cart that provides care staff with physical and informational support in their day-to-day work. The scientists at Fraunhofer IPA have now completed a first prototype. In doing so, they are continuing in their efforts to improve working conditions in the care sector and are developing solutions designed to address the challenges of demographic change.

Technical assistance systems can improve the difficult working conditions in residential nursing homes and hospitals by helping the staff in their work and...

Im Focus: A Grand Voyage for Tiny Organisms

Climate and Ecosystem Change in the Mediterranean

Since the opening of the Suez Canal in 1869 many hundreds of marine animal and plant species from the Red Sea have invaded the eastern Mediterranean, leading...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

Cells cling and spiral 'like vines' in first 3-D tissue scaffold for plants

27.08.2015 | Life Sciences

Hypoallergenic parks: Coming soon?

27.08.2015 | Health and Medicine

Stiffer breast tissue in obese women promotes tumors

27.08.2015 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>