Ultra-bright entangled-photon pair generation from an AlGaAs-on-insulator microring resonator

TL;DR

This paper presents a novel AlGaAs-on-insulator microring resonator that significantly enhances the brightness and quality of entangled photon pairs for quantum information, outperforming existing platforms.

Contribution

The work introduces an ultra-low-loss AlGaAs-on-insulator platform with a high-Q microring resonator capable of generating entangled photons with unprecedented brightness and purity.

Findings

Over 20 billion pairs per second per milliwatt squared generated

Near 1550 nm emission with >99% heralded photon purity

Violates Bell's inequality by over 40 standard deviations

Abstract

Entangled-photon pairs are an essential resource for quantum information technologies. Chip-scale sources of entangled pairs have been integrated with various photonic platforms, including silicon, nitrides, indium phosphide, and lithium niobate, but each has fundamental limitations that restrict the photon-pair brightness and quality, including weak optical nonlinearity or high waveguide loss. Here, we demonstrate a novel, ultra-low-loss AlGaAs-on-insulator platform capable of generating time-energy entangled photons in a $Q$ $>1$ million microring resonator with nearly 1,000-fold improvement in brightness compared to existing sources. The waveguide-integrated source exhibits an internal generation rate greater than $20\times 10^9$ pairs sec$^{-1}$ mW$^{-2}$, emits near 1550 nm, produces heralded single photons with $>99\%$ purity, and violates Bell's inequality by more than 40 standard deviations with visibility $>97\%$. Combined with the high optical nonlinearity and optical gain of AlGaAs for active component integration, these are all essential features for a scalable quantum photonic platform.