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Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Transport: Topological Insulators 3 (joint session with DS, HL, MA, O)

DS 17.8: Talk

Tuesday, March 17, 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 Ortix31CNR-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]

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