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Anomalous pumping in the non-Hermitian Rice-Mele model.

Journal of physics. Condensed matter : an Institute of Physics journal·2025
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Anomalous pumping in the non-Hermitian Rice-Mele model.

Abhishek Kumar1, Sarbajit Mazumdar2, S D Mahanti3

  • 1Department of Physics, University of Massachusetts Amherst, Amherst, MA 01003, USA, Amherst, Massachusetts, 01003, UNITED STATES.

Journal of Physics. Condensed Matter : an Institute of Physics Journal
|January 13, 2025
PubMed
Summary

Topological charge pumping in the Rice-Mele model with non-Hermiticity exhibits novel behaviors, including anomalous pumping and trivial protocols inducing charge transfer. This arises from unique point gap physics in non-Hermitian systems.

Keywords:
Anomalous pumpingBulk-boundary correspondenceNon-Bloch Chern numberNon-Hermitian topology

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Area of Science:

  • Condensed Matter Physics
  • Topological Materials
  • Non-Hermitian Systems

Background:

  • Topological charge pumping (TCP) describes charge transport in gapped systems driven by parameter variations.
  • Non-Hermitian systems introduce phenomena like skin effect and exceptional points, altering topological properties.
  • The Rice-Mele (RM) model is a 1D lattice model exhibiting topological transitions.

Purpose of the Study:

  • Investigate topological charge pumping in the Rice-Mele model with irreciprocal hopping and non-Hermiticity.
  • Explore the influence of non-Hermiticity on topological transitions and pumping phenomena.
  • Characterize novel pumping behaviors and their underlying mechanisms in non-Hermitian topological models.

Main Methods:

  • Utilized a finite-size generalized Brillouin zone (GBZ) scheme to distinguish edge modes from skin modes.
  • Analyzed topological transitions driven by non-Hermitian parameter gamma and system size N.
  • Reformulated a non-Bloch topological invariant for the 1+1D Rice-Mele model.

Main Results:

  • Identified gamma and N as independent tuning knobs for topological transitions in the static 1D RM model.
  • Demonstrated that standard topological pumping survives finite non-Hermiticity but can be modified by driving protocols.
  • Observed anomalous pumping and pumping from trivial protocols due to non-Hermitian point gap physics.

Conclusions:

  • Non-Hermiticity fundamentally alters topological charge pumping, leading to phenomena absent in Hermitian systems.
  • The generalized Brillouin zone scheme and non-Bloch topological invariant provide robust tools for analyzing non-Hermitian topological systems.
  • This study offers insights into engineering novel topological states and transport phenomena in non-Hermitian materials.