Viennese waltz - first live quantum key distribution network demonstration - UPDATED

Tony Austin
Monday, 13 October 2008 07:22

Opinion and Analysis

However they warn: "QKD networks are however not ubiquitous networks; they are closed, secret-key-based and distance-limited infrastructures, and their characteristics are intrinsically linked to the quantum nature of their physical layer. As a consequence, such networks fundamentally differ from classical Key Distribution infrastructures and cannot be deployed to secure open networks.

"We however believe that QKD networks are likely to find promising applications in high-security environments that were, up to now, relying solely on trusted couriers for Key Establishment. QKD-based systems can also be considered as an alternative to public-key-based systems for session key exchange in the context of secure networks relying on symmetric-key encryption schemes."

The SECOQC group is hoping to achieve ends like countering espionage, apparently including the Echelon signals intelligence (SIGINT) system run by the "friendly" AUSCANZUKUS signatory states.

The picture (courtesy Austrian Research Centers, click on it for an enlargement) shows one of the nodes.

The event was streamed live but unfortunately they didn't take the opportunity record it, which is quite an oversight, so the supplied stream link is dead.

Although these solutions are suitable for some applications such as connecting two data centres in a metropolitan area, they cannot address all scenarios requiring secure communication.

These limitations are related to a number of disadvantages of the point-to-point solutions: the maximum distance between sender and receiver is limited due to loss of photons in the optical fibre; the maximal speed of key generation is relatively low – it is comparable to that of a modem from the 1980’s – and the communication can be interrupted by simply cutting the fibre or interfering with the line of sight (in case of a free-space application).

In a network, longer distances can be bridged and alternative paths between sender and receiver can automatically be chosen in order to increase key generation throughput or prevent denial-of-service attacks even if a communication line is interrupted.

Furthermore, in a network, more than two partners can simultaneously obtain keys for encrypting confidential communication. This development will open up the possibility for telecom operators to develop novel services and products based on quantum cryptography.

If you want to do more reading in this esoteric field, try the International Journal of Quantum Information (IJQI) and get ready to impress your friends by casually dropping lines on such everyday matters as Non-Uniform Mixing Of Quantum Walk On Cycles or On The Non-Existence Of A Universal Hadamard Gate or Generating Quantum Entanglement In Scalable Superconducting Charge Qubits.

Remember that cat from an earlier page? Is it really there, or not? In researching this article, I came across Quantum physics says goodbye to reality where some physicists "giving the uneasy consequence that reality does not exist when we are not observing it."

UPDATE: These physicists are Austrian too. I wonder why so. There must be something in the Austrian water supply that makes them so concerned about reality! You know, Sigmund Freud, and all the rest of them. And what about this village in Austria, does psychoanalysis have its "roots" there? (Australian in joke.)

Until next time, from your sometimes here, sometimes there, unquantifiable iTWire reporter!