Circuit-based magnetless floquet topological insulator

Abstract

We explore the design and realization of a topological Floquet insulator in the form of a graphene-like honeycomb network of wye resonators, in order to achieve non-reciprocal transport with zero backward reflection over a continuous frequency range. The topological insulator here consists of two domains, with different topological orders induced by a periodic spatio-temporal modulation of the resonance frequency in each branch of suitably arranged wye resonators, creating a form of local `spinning'. The modulation in opposite directions breaks time-reversal symmetry in the lattice and produces a topologically protected edge state with a gapless dispersion crossing the bulk bandgap. The topologically protected edge states possess unique properties, such as one-way guiding, small group velocity dispersion, absence of backscattering, and immunity to structural disorder. Our analysis allows unveiling their peculiar propagation and confinement properties, and their inherent robustness to defects and loss.