European team bests Chinese record at teleporting distance

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European team bests Chinese record at teleporting distance
June 1, 2012 by Bob Yirka

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Quantum teleportation between the Canary Islands La Palma and Tenerife over both quantum and classical 143 km free-space channels. Image from arXiv:1205.3909v1.

(Phys.org) -- A European team of physicists has bested the record set by a team of Chinese researchers last month for distance in teleporting quantum bits (qubits). Where the Chinese team accomplished their feat by teleporting photons across a lake, the European team did so by performing the same feat across the ocean between two islands off the coast of Africa. It was apparently no easy feat as the team describes in the paper they’ve written and uploaded to the preprint server arXiv; they had so much foul weather to contend with that their experiment took nearly a year to complete. The record breaking distance by the Chinese team was close to 100 meters. The Europeans bested that mark by almost fifty meters, setting up a possible rivalry between the two teams to see which might be the first to successfully teleport a qubit to an orbiting satellite.



The work done by both teams, and many others across the globe in working out how to use entanglement of quantum bits of information to achieve a degree of teleportation is not just an exercise to prove that physics theories are correct; if qubits can be sent and read onboard satellites a new age in such communications is likely to be born, one where messages can be sent without worry that they are being decoded by others. That’s because common sense tells researchers that information that is sent instantaneously, without having to actually travel through the air, leaves no means for those that might wish to capture such data.

In their paper, the team says that they had to develop several different techniques to deal with all the noise that occurs when attempting to communicate not just through the air, but air that is volatile. This was made even more difficult by uncooperative weather and sand storms. One of those new techniques might just help pave the way to teleporting qubits much longer distances. They used entangled photons to synchronize the clocks that were used on both ends of their system to enable them to look at the qubits at both locations at very nearly the same instant in time. Prior to the development of this method, researchers had to rely on GPS synchronization. This new method reduced the event window from 10 nanoseconds to just 3.

The team notes that adapting their technique to teleport qubits to a satellite should be easier in some respects, as there is less noise when trying to teleport straight up as opposed to horizontally through the atmosphere. Of course, there will be the problem of adjusting for the movement of a satellite relative to equipment on the ground, but thus far neither team seems to see that as a problem.
European team bests Chinese record at teleporting distance
 
Uncle Ferd would like to teleport to France so he could meet a sexy French lady...
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Teleportation step toward quantum internet
Tue, 20 Sep 2016 - Physicists have set a new bar for quantum teleportation - transferring information from one place to another without anything physically travelling between the locations.
Two separate teams managed to teleport information across several kilometres of optical fibre network in two cities. This form of teleportation differs from that depicted in Star Trek: it involves transferring quantum states of a light particle, not Starfleet officers. But the method offers huge promise. Teleportation over long distances and across optical fibre networks is an important step towards the ultra-secure communications promised by quantum cryptography. And the set-ups described in studies published in Nature Photonics journal could be seen as building blocks for a future "quantum internet".

In one of the papers, Dr Wolfgang Tittel and colleagues describe how they teleported the quantum state of a photon, or light particle, over 8.2km in the Canadian city of Calgary. The process by which information - the quantum state of a photon - is teleported involves creating two photons at the University of Calgary (site B in the aerial photo). One of these photons is sent in a "classical" way along 11.1km of optical fibre to a building near Calgary City Hall (C in the photo), while the other remains behind at the university. Meanwhile, a photon is also sent to the City Hall site from site A (located in the neighbourhood of Manchester). This all results in the quantum state of the photon from site A being transferred to the photon which remained behind at the university (B) through quantum teleportation.

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This teleportation process occurs via a phenomenon known as entanglement, which describes how sub-atomic particles can be linked even if they are separated by a large distance. The details of entanglement are not well understood; it even befuddled Einstein, who famously described it as "spooky action at a distance". In the other Nature Photonics study, Qiang Zhang and Jian-Wei Pan from the University of Science and Technology of China, Shanghai, used a different set-up to achieve teleportation over a 30km optical fibre network in the Chinese city of Hefei.

In 2012, Anton Zeilinger of the University of Vienna carried out quantum teleportation over 143km of free space between different Canary Islands. But Dr Tittel says his study uses a configuration that could serve as the benchmark for useful city-based quantum networks. Both studies demonstrate that teleportation works over several kilometres of the optical fibre used in metropolitan areas. In future, theoretical devices known as repeaters could help amplify signals, enabling communications - a quantum internet, if you like - over much bigger distances.

This could enable the roll-out of much more secure communications offered by quantum cryptography. This would enable separate parties to produce a shared and random secret key known only to them that could be used to encrypt and decrypt messages. In the same issue of Nature Photonics, quantum information researcher Frédéric Grosshans from the Université Paris-Sud in Orsay, France, said: "Undoubtedly many interesting quantum information experiments in the future will be built on this work. "For the longer term, the two papers demonstrate that the possibility of quantum networks that span a city are a realistic proposition, which is an exciting vision for the future."

Teleportation step toward quantum internet - BBC News
 
Perhaps our radio telescopes are not going to detect anybody communicating by radio, because a technology fifty years beyond where we are today, no longer uses that form of communications. Kind of like the radio supplanted the telegraph.
 

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