A simple model for entangled photon generation in resonant structures

TL;DR

This paper introduces a simplified theoretical model for entangled photon generation via SPDC in resonant structures, facilitating easier design and analysis of quantum light sources in nano- and micro-scale devices.

Contribution

The authors develop and validate a simplified model that separates photon pair generation from resonant enhancement, streamlining the design process for quantum photonic sources.

Findings

Model agrees with rigorous theory at low gain

Simplifies calculations for photon pair generation

Accelerates design iteration for quantum sources

Abstract

The ability to engineer pairs of entangled photons is essential to quantum information science, and generating these states using spontaneous parametric down-conversion (SPDC) in nano- and micrometer-scale materials offers numerous advantages. To properly engineer such sources, a reliable model describing nano- and micrometer-scale SPDC is necessary; however, such a theoretical description remains a challenge. Here, we propose and derive a simplified model to describe SPDC in resonant structures, which considers the generation of photon pairs and the resonant enhancement of spectral bands to be separate processes, even though they actually occur simultaneously. We compare our simplified model to both the rigorous theory of SPDC in an etalon - a simple example of a resonant structure - and our experiments on SPDC in etalons and find agreement for low-gain SPDC. By simplifying the calculations required to generate photon pairs, our model promises to make designing complex resonant structures easier, and it promises to hasten the iteration of designs across the field of quantum state engineering.