Abstract: Entanglement is one of the most curious features of quantum physics, and has engendered much debate, from the days of the founders of quantum physics (Einstein, Schrödinger and others) to the present day, raising important issues such as local realism and strange and counter-intuitive correlations. Two correlated quantum systems can become much more correlated than classical physics would allow. Such correlations are not revealed when one looks at only one individual component of the system, even if the constituents are perfectly correlated — instead one sees a wholly mixed state of maximum entropy. I will discuss the relationship between unobserved correlations, entropy and information. Finally, in the last decade or two we have realized that entanglement offers new opportunities to encode, process and transmit information in ways quite different from classical physics. I will discuss how parallelism and entanglement, the characteristic features of the quantum world, enable us to undertake information processing tasks that are peculiar to the quantum world.
