Beyond bits
Information processing is currently implemented using quantities such as charges, voltages or currents in electronic devices which operate on the basics of classical physics. More specifically, conventional computers perform calculations on fundamental pieces of information called bits, which can take the values of 0 or 1. On the other hand, quantum information processing promises to employ the laws of quantum physics. A number of technologies are under investigation for their suitability to implement a quantum computer that uses quantum bits, representing both values of 0 and 1 at the same time. Research on quantum information processing needs therefore to be highly interdisciplinary and coordinated efforts led to the creation of a diverse consortium made up of the 15 QUPRODIS project partners. For a quantum computer, basic gate operations will be provided by logical operations on individual quantum bits and controlled coherent interactions between two quantum bits. As a fully theoretical project, QUPRODIS focused on information processing and transmission by controllable and distributed systems (atoms and molecules), exploiting quantum mechanical operations and new quantum algorithms. From the beginning of the project, new ideas emerged in connection with quantum coherence and entanglement, although theoretical work may be far ahead of experimental realisation of these ideas. Secret correlations are already an important resource in classical cryptography, where sender and receiver hold identical code books whose contents are only known to them. Entanglement, as a novel form of such secret correlations, will be a key resource in communication scenarios between distant laboratories. The transfer of concepts from quantum information theory to other fields of theoretical physics such as condensed matter physics or quantum field theory has also proved fruitful. Research work done within the QUPRODIS project was undoubtedly at the-state-of-art in several theoretical fields, providing a benchmark for possible future applications.
