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

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Thorsten Groh, Stefan Brakhane, Wolfgang Alt, Dieter Meschede, Janos Asbóth, Andrea Alberti


arXiv:1605.03633 [quant-ph]

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 temporal disorder in one- and two-dimensional discrete-time quantum walks. We also develop a simple analytical model to gain further insight into the robustness of these edge states against either spin or spatial dephasing. We find that the population of topologically protected edge states decays exponentially due to environment-induced decoherence. 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.