Silicon-Nitride Platform for Narrowband Entangled Photon Generation

TL;DR

This paper presents a silicon nitride photonic chip capable of generating narrowband, entangled photon pairs with high brightness and tunability, advancing integrated quantum photonics for quantum communication and memory interfacing.

Contribution

The work demonstrates an ultracompact, bright, entangled photon-pair source on a silicon nitride platform with unprecedented narrow bandwidth and simple temperature tuning, addressing key challenges in integrated quantum optics.

Findings

Photon pairs generated at rates exceeding 10^7 per second.

Selectable photon bandwidths down to 30 MHz.

Wavelength tunability via simple temperature control.

Abstract

CMOS-compatible photonic chips are highly desirable for real-world quantum optics devices due to their scalability, robustness, and integration with electronics. Despite impressive advances using Silicon nanostructures, challenges remain in reducing their linear and nonlinear losses and in creating narrowband photons necessary for interfacing with quantum memories. Here we demonstrate the potential of the silicon nitride (Si3N4) platform by realizing an ultracompact, bright, entangled photon-pair source with selectable photon bandwidths down to 30 MHz, which is unprecedented for an integrated source. Leveraging Si3N4's moderate thermal expansion, simple temperature control of the chip enables precise wavelength stabilization and tunability without active control. Single-mode photon pairs at 1550 nm are generated at rates exceeding 107 s-1 with mW's of pump power and are used to produce time-bin entanglement. Moreover, Si3N4 allows for operation from the visible to the mid-IR, which make it highly promising for a wide range of integrated quantum photonics applications.