# Rabi-like oscillation of photonic topological valley Hall edge states

## TL;DR

This paper demonstrates Rabi-like oscillations in photonic topological valley Hall edge states through weak periodic modulation, enabling controlled switching between edge states without altering the lattice's topological properties.

## Contribution

It introduces a novel method to induce resonant oscillations in valley Hall edge states via periodic modulation, expanding control over topological photonic systems.

## Key findings

- Resonant oscillations occur without changing lattice symmetry.
- Switching efficiency varies nonmonotonically with Bloch momentum.
- Detuning affects the resonance and switching efficiency.

## Abstract

We investigate Rabi-like oscillations of topological valley Hall edge states by introducing two zigzag domain walls in an inversion-symmetry-breaking honeycomb photonic lattice. Such resonant oscillations are stimulated by weak periodic modulation of the lattice depth along the propagation direction that does not affect the overall symmetry and the band topology of the lattice. Oscillations are accompanied by periodic switching between edge states with the same Bloch momentum, but located at different domain walls. Switching period and efficiency are the nonmonotonic functions of the Bloch momentum in the Brillouin zone. We discuss how efficiency of this resonant process depends on detuning of modulation frequency from resonant value. Switching of nonlinear edge states is also briefly discussed. Our work brings about an effective approach to accomplish resonant oscillations of the valley Hall edge states in time-reversal-invariant topological insulators.

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Source: https://tomesphere.com/paper/1905.09511