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HL: Fachverband Halbleiterphysik
HL 37: Transport: Topological insulators 3 (TT with HL/DS)
HL 37.8: Vortrag
Dienstag, 17. März 2015, 15:45–16:00, H 0110
Fractional quantization of the topological charge pumped in a 1D superlattice — •Pasquale Marra1, Roberta Citro1,2, and Carmine Ortix3 — 1CNR-SPIN, I-84084 Fisciano (Salerno), Italy — 2Dipartimento di Fisica “E. R. Caianiello”, Universitá di Salerno, I-84084 Fisciano (Salerno), Italy — 3Institute for Theoretical Solid State Physics, IFW Dresden, D-01069 Dresden, Germany
A one-dimensional quantum charge pump transfers a quantized charge in each pumping cycle. This quantization is topologically robust being analogous to the quantum Hall effect. The charge transferred in a fraction of the pumping period is instead generally not quantized. We show, however, that with specific symmetries in parameter space the charge transferred at well-defined fractions of the pumping period is quantized as integer fractions of the Chern number. We illustrate in details this fractional quantization in a one-dimensional Harper-Hofstadter model for both periodic and open boundary conditions, and discuss its relevance for cold atomic gases in optical superlattices.
[1] arxiv:1408.4457 [cond-mat]