Quantum spin computing, illustration. Quantum computers, which are under development, are based on quantum mechanics and the principle of representing information using quantum properties. This has the potential to massively increase computing power. In this illustration, an electric field (positive and negative poles shown) controls the spin state of particles such as electrons (blue) and effectively stretches them. As the current runs through the particles their frequency is changed, which can be observed by microwaves (green) in a phenomenon called 'stark shift'.