Companies will soon be able to securely encrypt their communications with data transmission that is completely impervious to interception using new quantum cryptography technology.

Siemens and a number of its partners have demonstrated the world's first quantum cryptography network in the world as part of the research project SECOQC.
The network combines seven high-security links on the basis of quantum cryptography, which is impervious to physical attack, and connects various Siemens locations in Austria.
Siemens also worked on the integration of the system and developed solutions for administering and monitoring the network, and is participating in the development of a quantum cryptography chip.
Quantum cryptography operates with photons, the carriers of light.
Because of the special features of quantum physics, the researchers involved – among them the famous scientist Anton Zeilinger – can use the photons to generate identical keys between two partners for secure transmission of data. Since any measurement of a photon leaves clear traces, an eavesdropper would be detected immediately.
This results from a fundamental principle of the complex world of quantum mechanics according to which a measured value is changed by the measurement itself.
In practice, the data transmission requires a quantum cryptography network. Without the network, the distances between the partners are limited, because photons cannot be transmitted arbitrarily far. The network passes the keys onward; in the experiment in Vienna, at any rate, it conveyed them over 85km. The scientists carried out a telephone conversation over the network, and the data was sent via optical fibres after having been encrypted securely with quantum cryptography.
The fibre-optic network was supplied by Siemens.