Limits of topological protection under local periodic driving

Abstract

The bulk-edge correspondence guarantees that the interface between two topologically distinct insulators supports at least one topological edge state that is robust against static perturbations. Here, we address the question of how dynamic perturbations of the interface affect the robustness of edge states. We illuminate the limits of topological protection for Floquet systems in the special case of a static bulk. We use two independent dynamic quantum simulators based on coupled plasmonic and dielectric photonic waveguides to implement the topological Su-Schriefer-Heeger model with convenient control of the full space- and time-dependence of the Hamiltonian. Local time-periodic driving of the interface does not change the topological character of the system but nonetheless leads to dramatic changes of the edge state, which becomes rapidly depopulated in a certain frequency window. A theoretical Floquet analysis shows that the coupling of Floquet replicas to the bulk bands is responsible for this effect. Additionally, we determine the depopulation rate of the edge state and compare it to numerical simulations.

Generalized laws of refraction and reflection at interfaces between different photonic artificial gauge fields

“…For details on the fabrication, see ref. 36 . The experimental measurement setup is sketched in Fig.…”

“…For details on the fabrication see Ref. 36 . The experimental set up is sketched in Fig 5 . We reflect a 700 nm laser beam off a spatial light modulator (SLM) to excite a Bloch mode with a given 𝑘𝑘 𝑦𝑦,inc while exciting the entire first Brillouin zone in 𝑥𝑥 (i.e., −𝜋𝜋 ≤ 𝑘𝑘 𝑥𝑥 𝑎𝑎 𝑥𝑥 ≤ 𝜋𝜋).…”

Robustness of quantized transport through edge states of finite length: Imaging current density in Floquet topological versus quantum spin and anomalous Hall insulators

“…2. However, specific to Floquet TIs is the possibility of Floquet replicas to couple to bulk bands [54,59]. That is, although edge states within the gap 0 are primarily built from states near the CNP of nonirradiated graphene, they also contain harmonic components near ±nhω which open the possibility for electronic photon-assisted tunneling into or out of states in the NM leads whose energies are far away from the CNP.…”

2D BeP2 monolayer: investigation of electronic and optical properties by driven modulated strain

“…13,17 Dirac semimetals are incredible directors of power, even though they have zero band gaps, and thus cannot be turned off. Due to the specic limitation of topology insulators in photonic devices, 18,19 we applied Lagrangian strain to the BeP 2 monolayer for bandgap opening. To date, there are no reports on engineering the physical and corresponding anisotropic properties of BeP 2 , and thus the present work focused on the examination of its in-plane anisotropic properties, including its stable structural, electrical, optical and anisotropies.…”