Topological approach to electron correlations at fractional quantum Hall effect

摘要: Abstract The classification of homotopy invariants in interacting multi-electron 2D systems at quantizing magnetic fields is presented, explaining the topologically protected correlations occurring integer and fractional quantum Hall effects. long-range entanglement essential for correlated phases contrast to binary conventional with local order parameters. induced by Coulomb interaction electrons has been derived terms invariants, which are universal robust against disorder single-particle crystal field, as illustrated experimental observations various materials different microscopic structure, like GaAs 2DES, graphene monolayer bilayer Chern topological insulators. demonstrated be immune perturbations, temperature chaos variation electron strength. nonzero repulsive between shown, however, definition disappear gaseous systems.