Broadband Entangled-Photon Pair Generation with Integrated Photonics: Guidelines and A Materials Comparison

TL;DR

This paper compares various integrated photonic materials for broadband entangled-photon pair generation, highlighting design strategies and material advantages for quantum communication applications.

Contribution

It provides a comprehensive evaluation of different materials and design approaches for broadband entanglement generation in integrated photonics.

Findings

Silicon nitride and lithium niobate enable broadband phase-matching.

Robust designs tolerate fabrication variations.

Type-1 cross-polarized phase-matching expands bandwidth.

Abstract

Correlated photon-pair sources are key components for quantum computing, networking, and sensing applications. Integrated photonics has enabled chip-scale sources using nonlinear processes, producing high-rate entanglement with sub-100 microwatt power at telecom wavelengths. Many quantum systems operate in the visible or near-infrared ranges, necessitating broadband visible-telecom entangled-pair sources for connecting remote systems via entanglement swapping and teleportation. This study evaluates broadband entanglement generation through spontaneous four-wave mixing in various nonlinear integrated photonic materials, including silicon nitride, lithium niobate, aluminum gallium arsenide, indium gallium phosphide, and gallium nitride. We demonstrate how geometric dispersion engineering facilitates phase-matching for each platform and reveals unexpected results, such as robust designs to fabrication variations and a Type-1 cross-polarized phase-matching condition for III-V materials that expands the operational bandwidth. With experimentally attainable parameters, integrated photonic microresonators with optimized designs can achieve pair generation rates greater than ~1 THz/mW$^2$.