[理论室报告] Topological Bloch oscillations
摘要：Topological invariants of crystalline topological insulators can be inferred from topological Bloch oscillations in electrical transport. In the presence of certain spatial (i.e. non-symmorphic) symmetries, electrical transport along symmetry-invariant directions results in period multiplication of the Bloch period, where the integer multiple is protected from perturbations that preserve the spatial symmetry.
For electric fields directed along other high-symmetry lines or planes, differences of Berry-Zak phases can be symmetry-protected to rational fractions of 2pi by spatial (symmorphic or non-symmorphic) symmetries. One consequence of such rational fractions is, that period multiplication occurs asymptotically for increasing lattice constants (atomic limit). We give necessary and sufficient criteria on the symmetry representation to determine spatially-protected Berry-Zak phases.