In topological insulators, global geometric phases of energy bands determine the existence of unidirectionally propagating edge states, which are immune to local defects, bringing a new stage for designing noise-resilient devices of electrons, photons and atoms. The geometric phase is measured by adiabatically transporting a quantum state through a Brillouin zone, which requires sophisticated quantum control technique. In atoms, such measurement can only be carried out at an extremely low temperature.
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Source: Phys.org