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

Tony Austin
Monday, 13 October 2008 07:22

Opinion and Analysis

In a significant advance for information security science, the first live quantum key distribution (QKD) network was just demonstrated in Vienna at the SECOQC Demonstration and International Conference.

When you start delving into quantum cryptography (quantum encryption), you're entering a world replete with concepts very unfamiliar to most of us.

As Wikipedia explains: "Quantum cryptography, or quantum key distribution (QKD), uses quantum mechanics to guarantee secure communication. It enables two parties to produce a shared random bit string known only to them, which can be used as a key to encrypt and decrypt messages.

An important and unique property of quantum cryptography is the ability of the two communicating users to detect the presence of any third party trying to gain knowledge of the key.

This results from a fundamental part of quantum mechanics: the process of measuring a quantum system in general disturbs the system. A third party trying to eavesdrop on the key must in some way measure it, thus introducing detectable anomalies."

Sort of like an extension of the uncertainty principle from the earliest days of quantum physics in the 1920s and 1930s, usually associated with the name of German theoretical physicist Werner Heisenberg?

No theoretical physicist am I (nor yourself, most likely), but it's all very thought-provoking. However, there's oodles of opportunity for both minor and major misconceptions.

One trap is the misuse of terms, such as the so-called observer effect (that the very act of observation will in itself make changes to the phenomenon being observed). This applies not just on the subatomic scale but also on the gross level. Thus, measuring an electric current can only be done by connecting an ammeter to the circuit thereby drawing an extra amount of current, and measuring a web server's throughput or response times or counting web page hits involves using extra code that slows down that server.

Then there's a famous thought experiment known as Schrödinger's cat in which it seems the cat is supposedly neither alive nor dead until observed. (In contrast, some politicians seem to remain dead even after being observed.)

However, most quantum physicists, in resolving Schrödinger's seeming paradox, now understand that the acts of 'observation' and 'measurement' must also be defined in quantum terms before the question makes sense.

In a similar vein, I hereby propose a corollary of the observer effect: Austin's theory of OS euphoric illusion. This states that if you extol the virtues of a particular operating system —such as Windows Vista or Ubuntu Linux— long enough, your sense of reality diminishes to the point where you cannot measure or appreciate the good points of any competing OS, and you get snared in a feature-list trap where you are compelled to build lists of OS features that asymptotically approach infinite length.

When you're moving in such esoteric levels of theoretical physics, it's ever so easy to wander off the beaten track and finish up in a land of absurdity, real Alice in Wonderland stuff, but splendid entertainment nevertheless.

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