Twisted Beams of Light Transmitted Over Large Distance Outdoors for First Time

A group of researchers from the University of Vienna and the Institute for Quantum Optics and Quantum Information have sent twisted beams of light across the rooftops of Vienna. It's 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. Previous research has shown that if a light beam of a certain color or wavelength is twisted into a corkscrew shape, the number of channels that data can be transmitted through can be drastically increased. Yet optical fibers are not always suitable, or available, for certain types of communication where light is used, so researchers have been trying to send twisted light over free space while simultaneously avoiding disturbances from air turbulence. Before now, this had only been achieved over small distances in the lab. The researchers 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. They 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 characterizing the 16 different patterns, the researchers then encoded the light with real information - grey-scale images of Wolfgang-Amadeus Mozart, Ludwig Boltzmann, and Erwin Schrödinger.