Hi everyone :)

Erbium

is a chemical element with the atomic number of 68, enabling us to store quantum information 10.000x longer compared to the efforts from other experiments. It's chemical symbol is ER and it is a rare earth element, occurring bound in monazite sand ores. Rare earth elements are a set of 17 elements in the periodic table with unique magnetic, luminescent, and electrochemical properties, which aren't really rare, but hard to mine as we can't find them in concentrations high enough for economical extraction. For example, we carry rare earths in our mobile phones or got them in our computer memory. Erbium is used as a key component of high-performance fiber optic communications in erbium-doped fiber amplifiers (EDFAs), as erbium oxide for coloring glass and other materials pink and in lasers.

erbium from the group of the "Lanthanides"                         

"For example, we carry rare earths in our mobile phones or got them in our computer memory." 

Memory is a good keyword.

The research team from the Australian National University (ANU) led by Matthew Sellars used crystals treated with erbium to extend the data storage time of quantum systems.  It is used in fiber optic networks, naturally operating at the right wavelength to boost communication signals. This effect can be used in quantum communication networks too.

What are quantum networks?

A quantum network allows physically separated quantum processors to transmit quantum information. Practically the same as a normal network, just with quantum computers. Unfortunately, this is way more difficult. Quantum entanglement is a very fragile priniciple, occurring when the quantum state of a particle of a group of particles can't described independently. Imagine giving someone a exact copy of a sheet of paper. If you start drawing on it, entanglement let the same drawing instantly appear to the other block as a result of their dependency. It is not a particle (block) which was sent, but an information(drawing) between them. The principle is way more difficult, but maybe this made it a bit easier to understand. 

We are having two coins in two different boxes which are entangled and are spinning around until one box gets opened. They keep being in a superposition (either head,number or both) until the box get's opened. As the state of the coin (showing number or head) is a relative, geometrical position from the observer to the coin. The decision made, can be determined before Bob even opened the box. Alice seeing a head on her coin means, Bob has to see a number (50/50 chance). This way is very simplified and lacks of information, but can get you a little overview if you don't know about the topic yet. Looking at particles, imagine looking at two particles, having a spin known to be 0 if paired. Mesuring particle one with the spin of 1/2, entanglement tells us the other one's spin is -1/2 without observing it as we know the pair has a spin of 0 (1/2 - 1/2 = 0).

But why do we need erbium?

Current problems are that photons can't be sent over long distances through fiber cables. They simply get destroyed after some distance. China used a satellite with the nickname "Micius" to solve this issue. A special crystal in it turned one photon into two which were entangled and sent them two two different ground stations. Due to the satellite, the signal was transmitted over 1200km from one base to the other. The team believes about 5 satellites would be enough if they travel in a higher orbit enabling a 24/7 available data transfer. Still, many other methods were tested (for some of them 8 meters were a long distance, meaning they have to get improved a lot more) and some of them even showed good results, the technological abilities we have, must get increased before we are able to set up this kind of a network in bigger dimensions.

connecting quantum computers around the world - science-fiction or reality in some years?

This job is done by scientists around the globe. Like the team from ANU with the successful alternative to current materials called "erbium."

With their investigations, they made the research team even states, the existing telecommunication system could be used by utilising these crystals as they are operating in the same 1550 nanometer bandwidth ( operation window of the glas in the fiber) as our existing telecommunication infrastructure. This would mean, it isn't necessary to build a whole new infrastructur e.g. satelittes, underwater cables...

How we are going to send qubits around the world in the future?

"Due to a lack of a suitable storage material, a quantum memory that  operates in the 1,550 nm optical fibre communication band with a storage  time greater than 1 μs has not been demonstrated." 

-from "Coherence time of over a second in a telecom-compatible quantum memory storage material", the teams nature.com article

According to that, their research is an innovative and necessary door opener. 

The team leader  Associate Professor Matthew Sellar said, erbium's versatility makes it possible to connect with many types of quantum computers including CQC2T's silicon qubits and the computers IBM and Google are developing. Another advantage is, it is operating at the same wavelength as the telecommunication infrastructure. No convertation from wavelength to wavelength is necessary, making their method far more realistic than approaching to the issue with other materials. Still ebrium isn't very good at storing quantum information because of the sensitivity to magnetic field fluctuations, taking place inside the crystals. Therefore a large magnetic field is necessary to quiet the magnetic field fluctuations inside the crystals and improving the storage time by the factor of 10.000! This result could change our view on the possibilities we can consider, implementing a world-wide quantum network. 

The future of quantum computing will be interesting and I hope to follow it through the different inventions the technology will face.

Thanks for reading :)

Source

Text

http://chemistry-reference.com/q_elements.asp?Symbol=Er

http://www.rareelementresources.com/rare-earth-elements#.WlBGe3lFcuW

http://www.rareearthtechalliance.com/What-are-Rare-Earths

https://en.wikipedia.org/wiki/Quantum_entanglement 

https://www.sciencealert.com/watch-this-is-how-quantum-entanglement-really-works

https://en.wikipedia.org/wiki/Erbium

https://en.wikipedia.org/wiki/Rare-earth_element

https://www.inverse.com/article/36317-quantum-internet-erbium-crystal

https://www.cqc2t.org/node/6911 

http://www.deutschlandfunk.de/spukhafte-fernwirkung-im-all-chinesischer-quantensatellit.676.de.html?dram:article_id=388868 (translated)

https://www.nature.com/articles/nphys4254

https://futurism.com/scientists-just-successfully-stored-quantum-information-10000-times-longer-than-ever-before/

Pictures

http://www.vanderkrogt.net/elements/images/elements/erbium.jpg

Picture 2 was designed with Canva.com

https://cdn.pixabay.com/photo/2017/12/14/14/23/blockchain-3019121_960_720.png

http://guardianlv.com/wp-content/uploads/2014/01/NASA-NEOWISE-Telescope-Finds-%E2%80%98Potentially-Hazardous%E2%80%99-Asteroid.jpg