Twisted light has been transmitted over Vienna rooftops over a large distance outdoors for the 1st time and could enable researchers to take advantage of the significant #data-carrying #capacity of light in both #classical and #quantum communications. This twisting characteristic, known as orbital angular momentum (#OAM), has been shown that it can be used to transmit 2.5 terabits of data/s- the carrying capacity of more than 66 DVDs -through an #optical fibre: which are not always suitable, or available, for certain types of communication where light is used eg #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 this study, they sent 16 different twisted configurations of a specific wavelength of light to a receiver 3 km away at the University of Vienna and #encoded the light with real info, #grey-scale images of Wolfgang-Amadeus Mozart, Ludwig Boltzmann and Erwin Schrödinger. 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. >>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. 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 = unbreakable quantum communications + the use of the OAM of light can make secret keys even tougher to crack. iop.org/news/14/nov/page_64430.html
Posted on: Wed, 12 Nov 2014 15:08:21 +0000
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