QUANTUM weirdness has finally made it out of the lab and into a commercial product. A Swiss start-up has become the first company in the world to sell a quantum cryptography system designed to guarantee the secrecy of messages sent along standard optical fibres.
The company, id Quantique, is exploiting technology developed at the University of Geneva, one of the world leaders in research into quantum cryptography. Gr茅goire Ribordy, a physicist at the university who runs the company, hopes the products will kick-start an industry that could be worth billions.
Quantum cryptography was conceived in 1984 by Charles Bennett at IBM鈥檚 Thomas J. Watson Research Center in New York and Gilles Brassard at the University of Montreal. The idea is to use quantum effects to transmit a 鈥渒ey鈥濃�攁 sequence of numbers that allows a scrambled message to be decoded鈥攕ecurely from one computer to another. The technique relies on the ability to create, manipulate and detect single photons of light.
Advertisement
No one has tried to commercialise the idea until now because the photon detectors needed to make it work relied on a large cooling system that鈥檚 only really at home in a lab. Now id Quantique has solved this problem by developing its own cooling system, based on the 鈥淧eltier effect鈥�, in which heat can be absorbed at the junctions of two metals when a current passes through them. The new cooler fits easily into a box the size of a PC.
Liberated from the clunky old cooler, the new cryptographic system can be fitted into just two desktop boxes, connected to each end of a fibre-optic cable. Each box contains a laser for generating single photons, a device for encoding information onto each photon and the Peltier-cooled detector for sensing photons when they arrive.
The system achieves its level of security by exploiting the fact that any measurement of a particle鈥檚 quantum properties alters these properties (see Diagram). This means that an eavesdropper cannot avoid changing a message he or she hacks into. Spotting an eavesdropper is simply a question of monitoring errors in the transmission.
The secure key is used to encrypt a message in the conventional way. As long as the key remains secret, so does the message. Even the toughest conventional encryption systems could, in theory at least, be broken in future, which is why governments, the military and commercial organisations all over the world are keen to find an alternative. Quantum cryptography guarantees that the key hasn鈥檛 been intercepted.
Bennett demonstrated the quantum technique for the first time in 1989. Later, in 1995, the Geneva team behind id Quantique became the first to test the idea outside the lab. Now, the company鈥檚 new 鈥減lug-and-play鈥� quantum encoder and decoder can send messages through standard telecoms optical fibre over distances of more than 60 kilometres.
Ribordy says initial interest in the system has come from the banking and insurance industries, who back up sensitive data to off-site computers at the end of each day. He believes this could become a growth area in the wake of the 11 September terrorist attacks, which drove home the need for secure communications.
Meanwhile, the company is cashing in on other quantum devices developed by the University of Geneva. It is already selling its single-photon detectors to other research groups involved in quantum optics around the world, and its quantum random number generators to Web security companies.
Random numbers are essential to the safety of secure transactions online but are difficult to generate using conventional computer algorithms because computers are inherently predictable. The id Quantique device generates its random numbers by analysing the paths photons take after they hit a semi-transparent mirror鈥攖hat is, whether they are reflected or transmitted. Because quantum physics is intrinsically random, these paths are too.