Robustness of topologically protected edge states in quantum walk experiments with neutral atoms

TL;DR

This paper investigates the robustness of topologically protected edge states in quantum walks with neutral atoms, combining numerical simulations, an analytical model, and an experimental proposal to observe dissipationless transport in optical lattices.

Contribution

It introduces a simple analytical model for edge state robustness against decoherence and proposes a feasible experimental setup using neutral atoms in optical lattices.

Findings

Edge states decay exponentially under decoherence.

Analytical model predicts robustness against spin and spatial dephasing.

Experimental scheme for observing unidirectional transport is feasible.

Abstract

Discrete-time quantum walks allow Floquet topological insulator materials to be explored using controllable systems such as ultracold atoms in optical lattices. By numerical simulations, we study the robustness of topologically protected edge states in the presence of decoherence in one- and two-dimensional discrete-time quantum walks. We also develop a simple analytical model quantifying the robustness of these edge states against either spin or spatial dephasing, predicting an exponential decay of the population of topologically protected edge states. Moreover, we present an experimental proposal based on neutral atoms in spin-dependent optical lattices to realize spatial boundaries between distinct topological phases. Our proposal relies on a new scheme to implement spin-dependent discrete shift operations in a two-dimensional optical lattice. We analyze under realistic decoherence conditions the experimental feasibility of observing unidirectional, dissipationless transport of matter waves along boundaries separating distinct topological domains.