Topological charge and spin pumping in a semiconductor nanowire

TL;DR

This paper proposes a method for achieving quantized charge and spin pumping in a semiconductor nanowire double-quantum-dot chain through adiabatic modulation of potentials and magnetic fields, highlighting the role of topological edge states.

Contribution

It introduces a novel scheme for topological charge and spin pumping in semiconductor nanowires using periodic modulation of potentials and magnetic fields, including effects of Rashba spin-orbit interaction.

Findings

Quantized charge transport achieved via potential modulation.

Topological spin pumping realized with magnetic field modulation.

Presence of gapless edge states correlates with topological pumping.

Abstract

The adiabatic topological pumping is proposed by periodically modulating a semiconductor nanowire double-quantum-dot chain. We demonstrate that the quantized charge transport can be achieved by a nontrivial modulation of the quantum-dot well and barrier potentials. When the quantum-dot well potential is replaced by a time-dependent staggered magnetic field, the topological spin pumping can be realized by periodically modulating the barrier potentials and magnetic field. We also demonstrate that in the presence of Rashba spin-orbit interaction, the double-quantum-dot chain can be used to implement the topological spin pumping. However, the pumped spin in this case can have a quantization axis other than the applied magnetic field direction. Moreover, we show that all the adiabatic topological pumping are manifested by the presence of gapless edge states traversing the band gap as a function of time.