Transport measurement of fractional charges in topological models

TL;DR

This paper proposes a transport measurement scheme to detect fractional topological charges in topological models, enabling experimental verification of charge quantization and distribution in systems like SSH and kagome models.

Contribution

It introduces a novel electronic transport method to measure fractional charges and their spatial distribution in topological systems, including higher-dimensional models.

Findings

Successfully verifies the $e/2$ charge in the SSH model.

Shows the scheme's robustness against disorder in higher-dimensional systems.

Demonstrates detection of $2e/3$ charge in the breathing kagome model despite disorder.

Abstract

The static topological fractional charge (TFC) in condensed matter systems is related to the band topology and thus has potential applications in topological quantum computation. However, the experimental measurement of these TFCs in electronic systems is quite challenging. We propose an electronic transport measurement scheme that both the charge amount and the spatial distribution of the TFC can be extracted from the differential conductance through a quantum dot coupled to the topological system being measured. For one-dimensional Su-Schrieffer-Heeger (SSH) model, both the $e/2$ charge of the TFC and its distribution can be verified. We also show that the Anderson disorder effect, which breaks certain symmetry related to the TFC, is significant in higher-dimensional systems while has little effect on the one-dimensional SSH chain. Nonetheless, our measurement scheme can still work well for specific higher-order topological insulator materials, for instance, the $2e/3$ TFC in the breathing kagome model could be confirmed even in the presence of disorder effect.