# Chiral quantum optics in photonic sawtooth lattices

## TL;DR

This paper proposes a new platform for chiral quantum optics using quantum emitters coupled to a photonic sawtooth lattice, enabling directional emission and tunable emitter interactions without relying on polarization.

## Contribution

It introduces a novel photonic sawtooth lattice model for chiral quantum optics, demonstrating directional emission and tunable interactions in a platform beyond nanophotonics.

## Key findings

- Achieves quasi-perfect directional emission when emitters are resonant with the band.
- Shows photons mediate tunable, complex emitter-emitter interactions within a band-gap.
- Proposes implementation in platforms like matter-waves and circuit QED.

## Abstract

Chiral quantum optics has become a burgeoning field due to its potential applications in quantum networks or quantum simulation of many-body physics. Current implementations are based on the interplay between local polarization and propagation direction of light in nanophotonic structures. In this manuscript, we propose an alternative platform based on coupling quantum emitters to a photonic \emph{sawtooth} lattice, a one-dimensional model with an effective flux per plaquette introduced by complex tunnelings. We study the dynamics emerging from such structured photonic bath and find the conditions to obtain quasi-perfect directional emission when the emitters are resonant with the band. In addition, we find that the photons in this bath can also mediate complex emitter-emitter interactions tunable in range and phase when the emitters transition frequencies lie within a band-gap. Since these effects do not rely on polarization they can be observed in platforms beyond nanophotonics such as matter-waves or circuit QED ones, of which we discuss a possible implementation.