The work of John Bell in the mid 1960s and experiments carried out to test his famous inequalities in the following decades have led to a detailed re-examination of the concepts of quantum mechanics, and revealed the full importance of the notion of entanglement. This reconsideration helped to generate the new and extremely rich field of research known as quantum information in the 1980s. The guiding idea behind this field of activity is that, by exploiting the specific rules of quantum physics, one can conceive of new ways of calculating and communicating, in which the rules of play are no longer the well-known classical rules.

One can thus develop new methods of cryptography in which the message is protected by the basic principles of quantum mechanics, and new computation methods that can be exponentially more efficient than classical algorithms. Quantum information is not therefore a mere sideline for physics, but concerns information theory, algorithmics and the mathematics of complexity theory. This research has already led to proposals for new algorithms and new computation architectures based on quantum logic gates with no classical equivalent. Still on the fundamental level, the meeting of information theory and quantum mechanics which lies at the heart of quantum information has led to a very stimulating regeneration of the theoretical tools used on both sides.