Broadband biphoton generation and polarization splitting in a monolithic AlGaAs chip

TL;DR

This paper demonstrates a monolithic AlGaAs chip capable of generating broadband orthogonally polarized photon pairs and efficiently splitting them, advancing integrated quantum photonics with high interference quality at room temperature.

Contribution

It introduces a novel monolithic AlGaAs chip that generates and separates broadband orthogonally polarized photon pairs on-chip, a key step for scalable quantum photonic circuits.

Findings

85% of photon pairs are deterministically separated over 60 nm bandwidth

Hong-Ou-Mandel interference visibility of 75.5% across the bandwidth

Operation achieved at room temperature and telecom wavelength

Abstract

The ability to combine various advanced functionalities on a single chip is a key issue for both classical and quantum photonic-based technologies. On-chip generation and handling of orthogonally polarized photon pairs, one of the most used resource in quantum information protocols, is a central challenge for the development of scalable quantum photonics circuits; in particular, the management of spectrally broadband biphoton states, an asset attracting a growing attention for its capability to convey large-scale quantum information in a single spatial mode, is missing. Here, we demonstrate a monolithic AlGaAs chip including the generation of broadband orthogonally polarized photon pairs and their polarization splitting; 85% of the pairs are deterministically separated by the chip over a 60 nm bandwidth. The quality of the two-photon interference at the chip output is assessed via a Hong-Ou-Mandel experiment displaying a visibility of 75.5 % over the same bandwidth. These results, obtained at room temperature and telecom wavelength, in a platform combining high second-order nonlinearity, electro-optic effect and direct bandgap, confirm the validity of our approach and represent a significant step towards miniaturized and easy-to-handle photonic devices working in the broadband regime for quantum information processing.