Ratchet effect in frequency-modulated waveguide-coupled emitter arrays

TL;DR

This paper investigates how periodic frequency modulation in waveguide-coupled emitter arrays induces a spatial asymmetry in emitter occupation, revealing conditions for maximal asymmetry and enhancement via topological edge states.

Contribution

It introduces the concept of a ratchet effect in frequency-modulated emitter arrays and analyzes optimal conditions and topological enhancements for this phenomenon.

Findings

Maximal asymmetry occurs under specific modulation conditions.

Topological edge states can enhance the ratchet effect.

The results are applicable to classical and quantum emitter systems.

Abstract

We study theoretically the spatial distribution of the polarizations in the array of resonant electromagnetic dipole emitters coupled to a one-dimensional waveguide. The ratchet effect manifests itself in the spatial asymmetry of the distribution of the emitter occupations along the array under symmetrical pumping from both sides. The occupation asymmetry is driven by the periodic modulation in time of the emitter resonance frequencies. We find numerically and analytically the optimal conditions for maximal asymmetry. We also demonstrate that the ratchet effect can be enhanced due to the formation of topological electromagnetic edge states, enabled by the frequency modulation. Our results apply to the classical structures with coupled resonators or arrays of semiconductor quantum wells as well as the quantum setups with waveguide-coupled natural or artificial atoms.