▎ 摘　　要

Quantum Hall effects in graphene occur in the unconventional form of (4e2)/(h)(n + 1/2), which is h shifted by a half integer on the Landau levels. The peculiar behaviors are fundamentally governed by massless Dirac fermions and the nontrivial topology of the band structure on the graphene in 2 + 1 dimensions. Charge carriers in bilayer graphene reveal chiral fermions with a parabolic energy spectrum and a zero-level anomaly accompanied by metallic conductivity. We also discuss briefly the possibility of studying a variety of unusual transport properties in the graphene system from the topological point of view and the techniques developed in the theories of 2 + 1 dimensional gravity.