# Transport signatures of symmetry protection in 1D Floquet topological insulators

## TL;DR

This paper investigates how transport measurements can reveal the symmetry-protected topological features of one-dimensional Floquet topological insulators, using theoretical predictions of transmission spectra under various boundary conditions.

## Contribution

It introduces a scheme to probe the unique transport signatures of 1D FTIs, considering different symmetry-preserving and breaking boundary perturbations, with detailed Green's function calculations.

## Key findings

- Transport spectra show distinct signatures depending on symmetry protection.
- Boundary perturbations influence the robustness of edge states.
- The proposed method can distinguish between different topological phases.

## Abstract

Time-periodic external drives have emerged as a powerful tool to artificially create topological phases of matter. Prime examples are Floquet topological insulators (FTIs), where a gapped bulk supports in-gap edge states, protected against symmetry-preserving local perturbations. Similar to an ordinary static topological insulator, the robustness of an edge state in a one-dimensional (1D) FTI shows up as a pinning of its quasienergy level, but now inside one of two distinct bulk gaps. Here we propose a scheme for probing this unique feature by observing transport characteristics of a 1D finite-sized FTI attached to external leads. We present predictions for transmission spectra using a nonequilibrium Green's function approach. Our analysis covers FTIs with time-independent and periodically driven boundary perturbations which either preserve or break the protecting chiral symmetry.