On 8 October, secure communication using quantum cryptography was demonstrated for the first time in a commercial telecommunications network by SECOQC ('Development of a global network for secure communication based on quantum cryptography'), an EU-funded project, at a meeting in Vienna, Austria. 'Quantum mechanics' describes the way we understand the fundamental nature of things at the infinitesimal level. Interestingly, the very act of measuring a quantum system disturbs it. Quantum cryptography, also called quantum key distribution (QKD), uses quantum mechanics to create 'secure' communication, wherein anyone listening in can be detected. In traditional cryptography, mathematical functions are used to create difficulties for any interloper. Such systems cannot guarantee security; their encryption is hard, but not impossible to break. QKD enables two parties to produce a shared 'key' that they can use to encrypt and decrypt messages. An eavesdropper would need to measure this key in some way, and this alone would create anomalies in the communication system. In other words, a third party can be detected by the very laws of nature that govern the system. The SECOQC project set out to create a long-range, high-security communication network that combined QKD with classical computer science. Great advances in quantum cryptography had already been made in the previous decade, and QKD products already exist that connect two users within a short distance of one another. However, significant challenges remained that made practical use of this technology difficult. The first problem was the fact that a quantum system uses quantum objects: photons, firing a million times a second along optical fibres. Photons travelling along optical fibres are lost over greater distances, making key generation very slow. Another difficulty was that communication between two users can be interrupted by simply cutting the fibre or interfering with the signal. Interruption can be devastating for business, and developing a network that is both secure and robust was essential for integrating QKD with modern business applications. SECOQC installed their network of cryptographic devices in a standard optical-fibre communication ring (provided by project partner Siemens) around Vienna. The six nodes and eight links were located between 6km and 82km apart. During the conference the project partners proved that the system worked: network-wide key generation and distribution, eavesdropper detection and other network functionalities were demonstrated. The SECOQC network succeeded in being both robust and secure. The network made bridging longer distances between users possible, and allowed for alternative paths between users to be automatically chosen. This made key generation faster and offered an automatic work-around in the event of an interruption in the communication line. This successful conclusion of the four-year project provides a basis for telecom operators to develop QKD-based products and services that can be integrated into modern business applications. International standards for this new technology will be developed by an 'Industry specification group on quantum key distribution and quantum technologies' under the direction of the European Telecommunication Standards Institute (ETSI) and representatives of industries as well as future users. The integrated project brought together experts in quantum physics and network specialists in addition to experts in cryptography, electronics, IT security, software development and economics. It comprised 41 participants (including 3 SMEs, 25 universities, 5 national research centres and 8 private enterprises) from 12 countries and was coordinated by ARC Seibersdorf research GmbH. The project was granted EUR 11.4 million by the 'Information society technologies' Thematic area of the Sixth Framework Programme (FP6).