Today's computers and other information processing devices manipulate information using what is known as the "classical" approximation to the laws of physics. However, we have known for some time that there is a more accurate description of the laws - the one provided by quantum mechanics. The study of how the laws of quantum mechanics affect computing, cryptography, and similar information processing tasksis known as quantum information processing.
In the 1990s, a sequence of results culminated in an efficient quantum algorithm for decomposing integers into their prime factors. No efficient classical algorithm is known for this problem, and its apparent hardness for classical computers is the foundation of the RSA encryption protocol widely used for e-commerce. Since then, fast quantum algorithms have been discovered for a variety of important problems. Quantum phenomena have a dramatic, and often counter-intuitive effect on other aspects of information processing as well. For instance, they enable cryptographic tasks such as secret key expansion with the guarantee that its security rests solely on the validity of quantum theory, as opposed to the conjectured hardness of a computational problem.
The current research expertise of the faculty spans quantum algorithms and complexity theory, the theory of quantum information and communication, and quantum cryptography. Together with the faculty at Institute for Quantum Computing and the proximate Perimeter Institute for Theoretical Physics they form one of the strongest and most diverse groups in quantum computation.