Topological insulators are exotic states of matter that show quantum-Hall-like behaviour in the absence of a magnetic field. Surface states in such systems are protected against scattering and are thought to provide an avenue for the realization of fault-tolerant quantum computing. Experiments now reveal the observation of such a topological state of matter in Bi2Se3, a naturally occurring stoichiometric material with a simple surface-state structure and a bulk energy gap larger than kBT at room temperature.
