# Design of the coherent diffusive photon gun for generating non-classical states

## TL;DR

This paper proposes a practical, integrated quantum light source using coherent diffusive photonics in waveguides, capable of generating non-classical states efficiently and feasibly with simplified models.

## Contribution

It introduces a novel design for a deterministic non-classical light source based on dissipatively coupled waveguides, with a comprehensive analysis of model validity and feasibility.

## Key findings

- Feasibility of generating bright sub-Poissonian light states from coherent input.
- Generation of non-classical states occurs early in the dynamics, simplifying modeling.
- Linear models can accurately describe the initial non-classical state generation.

## Abstract

We suggest and discuss a concept of deterministic integrated source of non-classical light based on the coherent diffusive photonics, a coherent light flow in a system of dissipatively coupled waveguides. We show how this practical quantum device can be realized with a system of single-mode waveguides laser-inscribed in nonlinear glass. We describe a hierarchy of models, from the complete multi-mode model of the waveguide network to the single mode coupled to a bath, analyze the conditions for validity of the simplest single-mode model and demonstrate feasibility of the generation of bright sub-Poissonian light states merely from a coherent input. Notably, the generation of non-classical states occurs at the initial stages of the dynamics, and can be accounted for in the linear model that allows us to circumvent the prohibiting computational complexity of the exact full quantum representation.