4.6 Article

Electron Pumping and Spectral Density Dynamics in Energy-Gapped Topological Chains

Journal

APPLIED SCIENCES-BASEL
Volume 11, Issue 2, Pages -

Publisher

MDPI
DOI: 10.3390/app11020772

Keywords

quantum dots; charge pumping; topology; atomic chains

Funding

  1. National Science Centre, Poland [2018/31/B/ST3/02370]

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This paper investigates electron pumping through energy-gapped systems and electron transport properties of a topological Su-Schrieffer-Heeger chain. The results show that the topologically trivial chain performs better in charge pumping than other normal or nontrivial chains. Additionally, during the perturbation process, electrons are pumped through temporary mid-gap states or induced sideband states.
Electron pumping through energy-gapped systems is restricted for vanishing local density of states at the Fermi level. In this paper, we propose a topological Su-Schrieffer-Heeger (SSH) chain between unbiased leads as an effective electron pump. We analyze the electron transport properties of topologically trivial and nontrivial systems in the presence of external time-dependent forces in the form of one-Gaussian or two-Gaussian perturbations (train impulses). We have found that the topologically trivial chain stands for much better charge pump than other normal or nontrivial chains. It is important that, during the perturbation, electrons are pumped through the mid-gap temporary states or through the induced sidebands states outside the energy gap. We also analyze the local density of states dynamics during the quench transition between different topological phases of the SSH chain. It turns out that after the quench, the edge topological states migrate through other sites and can temporarily exist in a topologically trivial part of the system. The tight-binding Hamiltonian and the evolution operator technique are used in our calculations.

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