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A laser achieves a quantum record

Hello World! This is the message with which a team of researchers from the University of Vienna (Austria) and the Max Planck Center for Quantum and Extreme Photonics in Ottawa (Canada), among others, have managed to test a science fiction technology capable of create "holograms" to send vast amounts of information through light.


Top Image: "Twisted light" traveling the distance of 143 kilometers between the islands, in just five thousandths of a second - University of Vienna


The experiments, carried out between the astronomical observatories of Tenerife and La Palma, 143 kilometers away, have made it possible to break all world records for laser communication. The findings have been recently published in the journal PNAs, and have shown that light can be twisted to contain a lot of information and also send it over long distances.


Specifically, they have used OAM spiral light beams to send from the summit of La Palma a series of codes that were projected in the form of images on the wall of a telescope in Tenerife.


These in turn were recognized by a computer thanks to an algorithm.


Image of the complex pulses of light sent, formed by photons with high quantum numbers - IQOQI Vienna / Robert Fickler


These strange beams of light have the peculiarity that they allow more information to be stored than straight beams. In conventional optical communications, each photon stores one bit of information (a 0 or a 1) through a quantum parameter known as polarity. But each of these "twisted light" photons can store tens of thousands of bits.


The researchers say that this technology is very promising for facilitating optical communications between the earth and satellites in space, but they acknowledge that it is still in its infancy. Even so, two years ago the researchers managed to carry out this transmission of information at a distance of three kilometers, but now they have greatly increased the distance, reaching 143 kilometers.


Despite the distortion suffered by light passing through 143 kilometers of atmosphere, the system only made 8.33% errors for each letter. However, he managed to decipher the message "Hello world!" with a single mistake, the final exclamation, which was mistaken for a "P".


Despite this achievement, and although the laser covered the distance between Tenerife and La Palma five thousandths of a second, the truth is that the work of deciphering the information required four and a half minutes .


"The entire transmission lasted 271 seconds, a speed comparable to that of smoke signals , the first long-distance communication system of antiquity," wrote the authors of one of the articles published in PNAs.


Image of the light falling on the observatory of Tenerife. Its ring shape is visible after traveling 143 kilometers - University of Vienna


Those responsible for the work emphasize that the important thing is that this laser transmission from La Palma to Tenerife shows that sending data by this procedure is possible in open spaces.


In addition, they point out that the "effective thickness" of the atmosphere vertically is only six kilometers (23 times less than the path between the two Canarian astronomical observatories), so they have stressed that optical communications from Earth to a satellite "do not they would be limited by turbulence.


Other parallel research also published in PNAs analyzed how photons of twisted light with high quantum numbers can be entangled. Entanglement is a feature of quantum mechanics whereby two particles "coordinate" or correlate their quantum states such that the value of any property, such as polarization, is the same for both particles at all times. This allows you to teleport information .


An investigation supported in part by the same scientists has already managed to teleport information between the observatories of La Palma and Tenerife, 143 kilometers away.

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