Universal Landau-Zener regimes in dynamical topological phase transitions

TL;DR

This paper investigates the dynamical behavior of topological phase transitions in finite systems, revealing universal Landau-Zener regimes and proposing the dc Hall response as a robust detection method independent of topological indices.

Contribution

It introduces a unified framework for understanding topological transitions across different boundary conditions and system sizes, highlighting universal Landau-Zener regimes.

Findings

Topological indices change regimes depend on ramp speed and system size.

A regime exists where topological indices remain unchanged at finite ramp speeds.

dc Hall response can detect topological transitions regardless of index behavior.

Abstract

In finite systems driven unitarily across topological phase transitions, the Chern number and the Bott index have been found to exhibit different behaviors depending on the boundary conditions and on the commensurability of the lattice. For periodic boundary conditions, the Chern number does not change for finite commensurate lattices (or in the thermodynamic limit). On the other hand, the Chern number can change for incommensurate lattices with periodic boundary conditions and the Bott index can change for lattices with open boundary conditions. Here we show that the scalings of the fields at which those two indices change exhibit Landau-Zener and near-adiabatic regimes depending on the speed at which the strength of the drive is ramped up and on the system size. Those regimes are preceded by a regime in which the topological indices do not change. The latter is the only regime that, for nonvanishing ramp speeds, survives in the thermodynamic limit. We then show that the dc Hall response can be used to detect topological phase transitions independently of the behavior of the topological indices.