Michelle Simmons, a professor from the Centre for Quantum Computer Technology, displays an image of the world's smallest transistor (right) built with just seven atoms in a single silicon crystal and measuring four nanometres in length, at the University of New South Wales in Sydney. The quantum transistor can be used to regulate and control electrical current flow like a commercial transistor but it represents a key step into a new age of atomic-scale miniaturisation and super-fast, super-powerful computers.