# Coherent nonlinear optics of quantum emitters in nanophotonic waveguides

## TL;DR

This paper reviews the progress in achieving coherent and nonlinear quantum light-matter interactions with solid-state emitters in nanophotonic waveguides, highlighting theoretical foundations, experimental benchmarks, and future challenges.

## Contribution

It provides a comprehensive overview of the theoretical and experimental advances in coherent nonlinear optics of quantum emitters in nanophotonic systems, emphasizing new protocols and challenges.

## Key findings

- Benchmark experimental realizations of coherent interactions
- Analysis of higher-order nonlinearities and multi-emitter coupling
- Identification of remaining challenges for full coherence

## Abstract

Coherent quantum optics, where the interaction of a photon with an emitter does not scramble phase coherence, lies at the heart of many quantum optical effects and emerging technologies. Solid-state emitters coupled to nanophotonic waveguides are a promising platform for quantum devices, as this combination is scalable. Yet, reaching full coherence in these systems is challenging due to the dynamics of the solid-state environment of the emitters. Here, we review progress towards coherent light-matter interactions with solid-state quantum emitters coupled to nanophotonic waveguides. We first lay down the theoretical foundation for coherent and nonlinear light-matter interactions of a two-level system in a quasi-one-dimensional system, and then benchmark experimental realizations. We then discuss higher-order nonlinearities that arise due to the addition of photons of different frequencies, more complex energy-level schemes of the emitters, and the coupling of multiple emitters via a shared photonic mode. Throughout, we highlight protocols for applications and novel effects that are based on these coherent interactions, the steps taken towards their realization, and the challenges that remain to be overcome.

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Source: https://tomesphere.com/paper/1906.08565