Tunable Topological Floquet Bound States in the Continuum in a Periodically Driven Double SSH Chain

We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum (BICs) via a class of systems constructed by coupling two identical periodically driven one-dimensional Su– Schrieffer–Heeger chains. The formation of topological Floquet BICs can be adjusted only by tuning the driving amplitude or frequency, regardless of whether the static system has BICs or not. The interchain bias can only change the localization property of topological Floquet BICs, and a bigger bias can lead to transforming topological Floquet BICs into bound states out of the continuum (BOCs). But it does not change the topological properties of these topological Floquet states. Based on the repulsion effect of edge states, we propose to detect occurrence of topological Floquet BICs and transition point between topological Floquet BICs and BOCs using quantum walk. Our work provided a convenient and realistic approach for the experimental realization and manipulation of BICs in a single-particle quantum system.