Local topological switch for boundary states in quantum walks
Xiang Zhan, Yue Yu, Peng Xue · Physical Review A · 2024
Localization is a critical phenomenon in quantum walks that has attracted much attention in quantum simulations. In this paper, we present a unified framework for investigating the localization due to two causes, single-position defects and topology. Furthermore, we show that a specific phase defect can act as a topological switch, which can turn on (off) topological boundary states between two regions with the same (different) topological numbers. Remarkably, the localized state turned on by the switch is protected by topological features. Thus, the switch is a topologically nontrivial defect that significantly differs from ordinary defects. Our results provide new intuitive insight into the topological features of quantum walks and shed new light on manipulating quantum walks.