Quantum computing  A classical computer runs programs which process definite input states and produce corresponding outputs. It was realised in the 1980s that quantum theory gives us a new computing paradigm with radically different architecture and properties. A quantum computer can process a superposition of many different classical inputs and produce a superposition of outputs, and quantum entanglement means that the number of superposed states can be increased exponentially by linearly increasing the physical resources. In theory, this quantum parallelism can be utilized for solving problems which are intractable on any classical computer. The factorization of large composite integers (which would facilitate the breaking of the well known RSA public key cryptosystem!) and the discrete logarithm problem are two examples. The Quantum Information Processing Group is working on both the theory and practical implementation of quantum computing, collaborating in the development of promising technologies for quantum gates and networks, designing new quantum algorithms and investigating the consequences of QIP for conventional information security.
