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Arthur T Knackerbracket has found the following story:
For the first time, a team led by Innsbruck physicist Ben Lanyon has sent a light particle entangled with matter over 50 km of optical fiber. This paves the way for the practical use of quantum networks and sets a milestone for a future quantum internet.
The quantum internet promises absolutely tap-proof communication and powerful distributed sensor networks for new science and technology. However, because quantum information cannot be copied, it is not possible to send this information over a classical network.
In a nonlinear crystal illuminated by a strong laser the photon wavelength is converted to the optimal value for long-distance travel. Quantum information must be transmitted by quantum particles, and special interfaces are required for this. The Innsbruck-based experimental physicist Ben Lanyon, who was awarded the Austrian START Prize in 2015 for his research, is researching these important intersections of a future quantum Internet.
Now his team at the Department of Experimental Physics at the University of Innsbruck and at the Institute of Quantum Optics and Quantum Information of the Austrian Academy of Sciences has achieved a record for the transfer of quantum entanglement between matter and light. For the first time, a distance of 50 kilometers was covered using fiber optic cables.
"This is two orders of magnitude further than was previously possible and is a practical distance to start building inter-city quantum networks," says Ben Lanyon.
[...] With 100-kilometer node spacing now a possibility, one could therefore envisage building the world’s first intercity light-matter quantum network in the coming years: only a handful of trapped ion-systems would be required on the way to establish a quantum internet between Innsbruck and Vienna, for example.
[...] Light-matter entanglement over 50 km of optical fibre. V. Krutyanskiy , M. Meraner, J. Schupp, V. Krcmarsky, H. Hainzer and B. P. Lanyon. npj Quantum Information 2019 DOI: https://doi.org/10.1038/s41534-019-0186-3 (Open Access)
(Score: 2) by HiThere on Sunday September 01 2019, @06:06PM (2 children)
More to the point, it won't work past a repeater even on a wired connection. But that may be the next step...however it looks to me (a non-specialist) as an especially tricky one. Otherwise the signal could be copied at every amplifier stage it hits.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by kazzie on Sunday September 01 2019, @08:55PM (1 child)
The fact that one can't use amplification en-route without breaking the entanglement (i.e. it's s passive optical network) is a major range limitation.
I know of research in the Cambridge/Ipswich area of the UK that's looking into using entanglement in between each pair of optical amplifiers, and using the low-bandwidth entangled channel to regularly exchange encryption keys for a non-entangled optical signal that's sent alongside it. But iirc, that still leaves the issue of having to trust the amplifier nodes.
(Score: 0) by Anonymous Coward on Monday September 02 2019, @02:03PM
uhm ... I wonder if it's possible to get better range with entangled particles than prior? For instance see
https://soylentnews.org/article.pl?sid=19/08/31/0151247 [soylentnews.org]
It seems to claim that entanglement can make radar less noisy. Less noise = further range?
What would be the increase in range though? Fewer amplifier nodes required than prior? More bandwidth with fewer amplifier nodes? Could be useful for something.