Subscribe free to our newsletters via your
. 24/7 Space News .

Twisted light waves sent across Vienna
by Staff Writers
Washington DC (SPX) Nov 13, 2014

The 3 kilometer free-space experiment was performed in the city of Vienna, from ZAMG (Zentralanstalt fur Meteorologie und Geodynamik, Central Institute for Meteorology and Geodynamics) to our institute IQOQI. Picture of an alignment laser from IQOQI to ZAMG, captured at ZAMG. Image courtesy New Journal of Physics/IOP Publishing.

A group of researchers from Austria have sent twisted beams of light across the rooftops of Vienna. It is the first time that twisted light has been transmitted over a large distance outdoors, and could enable researchers to take advantage of the significant data-carrying capacity of light in both classical and quantum communications.

The results of the experiment have been published in the Institute of Physics and German Physical Society's New Journal of Physics, and are accompanied by a video abstract, which can viewed here.

Previous research has shown that if a beam of a certain colour, or wavelength, of light is twisted into a corkscrew shape, the number of channels that data can be transmitted through can be drastically increased. Instead of using one wavelength of light as one channel of communication, the light can be theoretically twisted with an infinite number of turns, with each configuration acting as a single communication channel.

This twisting characteristic, known as orbital angular momentum (OAM), has been exploited by researchers in the past, with some showing that it can be used to transmit 2.5 terabits of data per second--the carrying capacity of more than 66 DVDs--through an optical fibre.

Yet optical fibres are not always suitable, or available, for certain types of communication where light is used--such as Earth to satellite communications--so researchers have been trying to send twisted light over free space whilst at the same time avoiding disturbances from air turbulence. So far, this has only been achieved over small distances in the lab.

In the current study, the researchers, from the University of Vienna and the Institute for Quantum Optics and Quantum Information, used a green laser beam to send twisted light through a lens on top of a radar tower at the Central Institute for Meteorology and Geodynamics in Vienna.

The researchers sent 16 different twisted configurations of a specific wavelength of light to a receiver 3 km away at the University of Vienna. A camera was used to capture the beams of light and an artificial neural network was deployed to reveal the pattern and remove any possible disturbances that may have been caused by air turbulence.

After distinguishing and characterising the 16 different patterns, the researchers then encoded the light with real information-- grey-scale images of Wolfgang-Amadeus Mozart, Ludwig Boltzmann and Erwin Schrodinger.

Co-author of study Mario Krenn said: "We have shown for the first time that information can be encoded onto twisted light and sent through a 3 km intra-city link with strong turbulences.

"The OAM of light is theoretically unbounded, meaning that one has, in theory, an unlimited amount of different distinguishable states in which light can be encoded. It is envisaged that this additional degree of freedom could significantly increase data-rates in classical communication."

Krenn and his co-authors also believe that the OAM of light can be used in quantum communication experiments, whereby a secret key made from a string of polarised, or "spinning", photons--individual particles of light--is passed between two individuals to protect data they want to share with each other.

The laws of physics dictate that any attempt by an eavesdropper to intercept the key and try and measure the "spin" of the photons will inherently alter the spin and thus destroy the secret key.

This type of quantum communication has subsequently been labelled as "unbreakable" and Krenn believes that the use of the OAM of light can make secret keys even tougher to crack.

"Quantum communication could profit greatly from the almost infinite number of OAM states. Each single photon can carry an OAM number, thus carrying more information than just one spin, or polarisation, as is common in the most recently proposed quantum experiments," Krenn continued.

"A higher information density could make the secret key more robust against several side-channel attacks by eavesdroppers, which is, of course, a serious problem as we have seen in recent months."

Timeline of the twist
1992: Researchers begin to study the orbital angular momentum of light (

2004: The first successful transmission of data using twisted light in the lab (

2012: Twisted microwaves are sent 450 m over free space (

2012: Researchers transmit terabits of data per second using the OAM of light (

2013: Terabits of data per second are transmitted in a specialised optical fibre using the OAM of light (

2014: Two photons are entangled with 103 dimensions using the OAM of light (

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only


Related Links
Institute of Physics
Understanding Time and Space

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Good vibrations give electrons excitations
Oak Ridge TN (SPX) Nov 11, 2014
For more than 50 years, scientists have debated what turns particular oxide insulators, in which electrons barely move, into metals, in which electrons flow freely. Some scientists sided with Nobel Prize-winning physicist Nevill Mott in thinking direct interactions between electrons were the key. Others believed, as did physicist Rudolf Peierls, that atomic vibrations and distortions trumped all ... read more

After Mars, India space chief aims for the moon

China examines the three stages of lunar test run

China gears up for lunar mission after round-trip success

NASA's LRO Spacecraft Captures Images of LADEE's Impact Crater

Warmth and flowing water on early Mars were episodic

Next NASA Mars Mission Reaches Milestone

Mars, too, has macroweather

Comet lander 'working well', but may be on slope

Tencent looks to the final travel frontier

ESA Commissions Airbus As contractor For Orion Service Module

Study Investigates How Men and Women Adapt Differently to Spaceflight

S3 concludes first phase of drop-tests

China publishes Earth, Moon photos taken by lunar orbiter

China plans to launch about 120 applied satellites

Mars probe to debut at upcoming air show

China to build global quantum communication network in 2030

Europe's 3D printer set for ISS

NASA Commercial Crew Partners Continue System Advancements

Astronaut turned Twitter star, Reid Wiseman, back on Earth

Three-man multinational space crew returns to Earth

Time-lapse video shows Orion's move to Cape Canaveral launch pad

Soyuz Installed at Baikonur, Expected to Launch Wednesday

SpaceX chief Musk confirms Internet satellite plan

Orbital recommits to NASA Commercial program and Antares

Follow the Dust to Find Planets

NASA's TESS mission cleared for next development phase

ADS primes ESA's CHEOPS to detect and classify exoplanets

NASA's TESS Mission Cleared for Next Development Phase

Shaking the topological cocktail of success

Drexel Engineers Improve Strength, Flexibility of Atom-Thick Films

Creating Bright X-Ray Pulses in the Laser Lab

New Process Isolates Promising Material

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.