Devil's staircase of incompressible electron states in a nanotube

TL;DR

This paper demonstrates how a periodic potential in a nanotube can create incompressible electron states through different mechanisms, leading to quantized current phenomena detectable via a Thouless pump setup.

Contribution

It introduces a new understanding of incompressible states in nanotubes influenced by periodic potentials and electron interactions, with potential experimental detection methods.

Findings

Incompressible states arise from Bragg diffraction and Wigner crystal pinning.

Excitation gaps depend on electron binding strength to the potential.

Quantized current can be achieved through a Thouless pump setup.

Abstract

It is shown that a periodic potential applied to a nanotube can lock electrons into incompressible states. Depending on whether electrons are weakly or tightly bound to the potential, excitation gaps open up either due to the Bragg diffraction enhanced by the Tomonaga - Luttinger correlations, or via pinning of the Wigner crystal. Incompressible states can be detected in a Thouless pump setup, in which a slowly moving periodic potential induces quantized current, with a possibility to pump on average a fraction of an electron per cycle as a result of interactions.