Complete graph in a quantum network for eight participants – discussing this experiment

The other day we talked about a study in which a quantum key distribution mechanism was proposed for ten network participants. We continue to look at similar projects.


A photo – Joshua sortino – Unsplash

What is this project

A new system for distributing data over quantum communication channels among several participants presented an international group of engineers from the laboratories of the University of Bristol, the Institute for Quantum Optics and Information in Vienna, the Ruger Boscovic Institute in Zagreb, the PLA Defense Science and Technology University and the University of Leeds.

The implementation of a quantum network demonstrated by scientists is different from the one we discussed earlier. The developers of this project showed their own solution to a number of problems – from the efficiency of scaling to strengthening the security of classical quantum networks.

What the implementation looks like

As part of the experiment, engineers connected each “user” of the network with others, forming complete graph with the number of pairs equal to twenty-eight. AT article there is a general outline of the architecture (p. 3) and its experimental representation for Bristol (p. 4).

Image – Koko90 – (CC BY-SA)
Key distributions were performed for all twenty-eight pairs of users with the option to select four of them as priority ones. Plus, they used the method of two-particle quantum entanglement between the frequency modes of the signal. Avoiding multiparticle entanglement towards a simpler solution and a new approach to the network topology made it possible to use a minimum of equipment (detectors, etc.) to maintain it.

Trusted nodes are also excluded in this project. This is the second key difference from the project presented earlier by a group of physicists from South Africa. The project developers conducted the first tests with eight participants named a record for systems of this type, which are a new alternative to classical point-to-point quantum networks.

Development prospects

The system designers say that their approach is suitable for a wide range of use cases and allows for efficient key distribution for geographically dispersed network participants. This is another step towards the deployment of large-scale quantum networks and the quantum Internet. Another thing is that in order to implement such plans, it is necessary to significantly advance not only research in this area. As our Russian colleagues rightly point out, the development of the direction will require significant efforts in equipment certification.


A photo – Josh adams – Unsplash

Although the scientists who conducted the experiment in Bristol put forward a number of possible improvements for large-scale implementations with topology in the form of a complete graph – for example, they propose to use additional detectors on a number of nodes (several on one), it is known that even experimental quantum networks are “enough capricious, low-speed and expensive. “

Therefore, attenuated laser radiation is often used today. Who is working on the implementation of commercial developments in this area, we will tell in one of the following materials.


What we write about in the corporate blog 1cloud.ru:

Unusual interview invitations – from the HTTP header to the message in the search engine
Why the old options for monitoring employee performance are not suitable for telecommuting
Why developers are more valuable than money, how to save and increase them

Screening of mobile devices – how things are in the world
Development team suggests switching to UTF-8
What are the open operating systems for network equipment


New publications on our Habré:

  • Quantum communications: a key distribution system for ten network participants
  • “Restructuring” of IT monopolies, breaking cookie walls and open “gossoft” – cloud TL; DR
  • TL; DR: Unusual “remote control” and the issue of screening personal gadgets
  • Who will deal with the security of open source software – new projects and their future


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