HN Academy

That research quantum network has a different purpose. Quantum key distribution (QKD) as mentioned in the article has been commercially available for a number of years now (for example by ID Quantique [1]). These products rely on having a direct connection, i.e. a single fibre line without repeaters or other ‘interruptions’. This limits their range to about 100km (20dB attenuation).

The research network in The Netherlands is more ambitious than that. The researchers’ goal is to build a true quantum internet, with ‘quantum repeaters’ that allow connections over longer distances [2]. These quantum repeaters work on the principe of quantum entanglement generation and purification to achieve quantum teleportation of qubits to allow end to end communication [3].

If you’re interested in learning more about this, I can highly recommend the free edX course by TU Delft and Caltech on quantum cryptography [4].

[1]: https://www.idquantique.com/quantum-safe-security/overview/q... [2]: https://qutech.nl/roadmap/quantum-internet/ [3]: https://en.m.wikipedia.org/wiki/Quantum_network#Quantum_repe... [4]: https://www.edx.org/course/quantum-cryptography-0

This is currently on edx. Its more advanced that the courses mentioned here. I do not know what edx will do after the course ends, but if you want it you can get it while it ss still available.

https://www.edx.org/course/quantum-cryptography-caltechx-del...

Quantum Cryptography by Thomas Vidick (Caltech) and Stephanie Wehner (Delft University)

⬐ tptacek

This is certainly not the first thing you want to learn in cryptography, for many reasons.

⬐ hannob

So-called Quantum Cryptography is largely snake oil. The most important things you need to know about it is that:

* In order to do QC you need an authenticated channel first. QC proponents hardly mention that or try to obscure it, but it basically means you can't have QC unless you already have some other secure cryptography.

* QC has severe practical limits. It needs a point to point connection capable of sending physical particles. That means: No Wifi, no mobile Internet and no connections over large distances. Given that these people recently started talking about a "Quantum Internet" makes this simply ridiculous.

⬐ bogomipz

Is there a working and practical implementation somewhere? I was under the impression it wasn't practical yet.

⬐ hannob

You can buy it: http://www.idquantique.com/

It's probably insecure (these things get broken regularly), not practical for any real use case and total obvious nonsense to buy it, but I think there are some banks who thought they have some money leftover that they'd sink in such devices.

⬐ jpt4

Of the first point I shall plead Wittgenstein and not speak, but as regards the second: In what way are photons, the medium of wireless telecommunication, not physical particles? In what way are, indirect connections not decomposable into multiple direct connections (broadcast vs. point-to-point is a more robust difference, I agree)?

⬐ marcosdumay

For QC to work, the receiver must receive the exact same photons the transmitter created. Those photons can not be tampered with, what means they can not be relayed, or reflected by most surfaces.