Tracking the quantized information transfer at the edge of a chiral Floquet phase

TL;DR

This paper demonstrates that the chiral unitary index in chiral Floquet phases can be interpreted as a quantized transfer of quantum information along the edge, and proposes a measurement method for this transfer.

Contribution

It introduces the chiral mutual information as a new way to interpret the topological invariant and provides a physical setup to measure quantum information transfer in Floquet phases.

Findings

Chiral mutual information quantifies chiral information transfer.

A physical measurement setup for the chiral transfer is proposed.

The chiral unitary index is linked to quantized quantum information flow.

Abstract

Two-dimensional arrays of periodically driven qubits can host inherently dynamical topological phases with anomalous chiral edge dynamics. These chiral Floquet phases are formally characterized by a dynamical topological invariant, the chiral unitary index. Introducing a quantity called the chiral mutual information, we show that this invariant can be precisely interpreted in terms of a quantized chiral transfer of quantum information along the edge of the system, and devise a physical setup to measure it.