Immutable quantized transport in Floquet chains

TL;DR

This paper introduces a new form of robust, immutable quantized transport in Floquet chains, which is unaffected by strong perturbations and does not rely on a band gap, expanding the understanding of topological phenomena.

Contribution

It presents the concept of a shiftbox and demonstrates how to achieve immutable quantized transport in Floquet chains, independent of topological phase transitions.

Findings

Transport is unaffected by strong perturbations.

Quantized transport is achieved without a band gap.

Model systems exhibit strictly quantized chiral and helical transport.

Abstract

We show how quantized transport can be realized in Floquet chains through encapsulation of a chiral or helical shift. The resulting transport is immutable rather than topological in the sense that it neither requires a band gap nor is affected by arbitrarily strong perturbations. Transport is still characterized by topological quantities but encapsulation of the shift prevents topological phase transitions. To explore immutable transport we introduce the concept of a shiftbox, explain the relevant topological quantities both for momentum-space dispersions and real-space transport, and study model systems of Floquet chains with strictly quantized chiral and helical transport. Natural platforms for the experimental investigation of these scenarios are photonic Floquet chains constructed in waveguide arrays, as well as topolectrical or mechanical systems.