FisMat2017 - Submission - View

Abstract's title: Non-adiabatic breaking of topological pumping
Submitting author: Lorenzo Privitera
Affiliation: Sissa
Affiliation Address: Via Bonomea 265, Trieste, 34136, Italy
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Angelo Russomanno (Scuola Normale Superiore - Pisa; ICTP -Trieste) Rosario Fazio (NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, I-56126 Pisa) Roberta Citro (Università di Salerno) Giuseppe E. Santoro (Sissa; CNR-IOM Democritos National Simulation Center; ICTP)
Abstract

Thouless adiabatic quantum pumping [1] is a cornerstone in condensed matter physics. It lays the conceptual foundations to many aspects of the field of topological insulators. Recently, systems explictly realizing a topological quantum pump have been realized in cold-atom experiments. In this work, we study what happens out of the perfect adiabatic limit. Within a Floquet framework, we analyze the features of the transported charge as a function of the frequency of the driving. Most importantly, we find that the system is not topologically robust to non-adiabatic effects.  The long-time average value of the trasported charge, described by the Floquet diagonal ensemble, shows deviations from the topologically quantized limit which are quadratic in the frequency, on the contrary of previous works [4], which found instead exponentially small corrections to the quantized value. The charge transported in the first period shows beatings-like oscillations on top of the diagonal value, in accordance with a theorem of Avron and Kons [5].

References:

[1] D. J. Thouless, "Quantization of particle transport." Physical Review B 27.10 (1983): 6083.

[2] M. Lohse et al. "A Thouless quantum pump with ultracold bosonic atoms in an optical superlattice." Nature Physics 12.4 (2016): 350-354.

[3] S. Nakajima, et al. "Topological Thouless pumping of ultracold fermions." Nature Physics (2016).

[4] W.K. Shih and Q. Niu. "Nonadiabatic particle transport in a one-dimensional electron system." Physical Review B 50.16 (1994): 11902.

[5]  J. E. Avron and Z. Kons, "Quantum response at finite fields and breakdown of Chern numbers." Journal of Physics A: Mathematical and General 32.33 (1999): 6097.