# Universal non-analytic behavior of the non-equilibrium Hall conductance in Floquet topological insulators

## TL;DR

This paper reveals universal non-analytic behaviors of the Hall conductance in Floquet topological insulators after sudden driving amplitude changes, extending static system results to driven systems.

## Contribution

It demonstrates that the Hall conductance exhibits universal non-analytic laws near phase transitions in Floquet topological insulators, generalizing static system findings to driven cases.

## Key findings

- Logarithmic divergence of Hall conductance for gapped initial states.
- Quantized jumps of Hall conductance for gapless initial states.
- Universal non-analytic behavior near phase transitions.

## Abstract

We study the Hall conductance in a Floquet topological insulator in the long time limit after sudden switches of the driving amplitude. Based on a high frequency expansion of the effective Hamiltonian and the micromotion operator we demonstrate that the Hall conductance as function of the driving amplitude follows universal non-analytic laws close to phase transitions that are related to conic gap closing points, namely a logarithmic divergence for gapped initial states and jumps of a definite height for gapless initial states. This constitutes a generalization of the results known for the static systems to the driven case.