High-quality photonic entanglement for wavelength-multiplexed quantum communication based on a silicon chip

TL;DR

This paper presents a silicon photonics chip that efficiently generates high-purity energy-time entangled photon pairs across multiple telecom channels, advancing integrated quantum communication technology.

Contribution

The work introduces a CMOS-compatible silicon ring resonator that produces bright, noise-free entangled photon pairs suitable for wavelength-multiplexed quantum networks.

Findings

Spectral brightness of 400 pairs/s/MHz at 500 μW pump power

High raw visibility (>98%) across telecom channels

Generation of a frequency comb compatible with telecom multiplexers

Abstract

We report an efficient energy-time entangled photon-pair source based on four-wave mixing in a CMOS-compatible silicon photonics ring resonator. Thanks to suitable optimization, the source shows a large spectral brightness of 400\,pairs of entangled photons /s/MHz for $\rm 500\,\mu W$ pump power. Additionally, the resonator has been engineered so as to generate a frequency comb structure compatible with standard telecom dense wavelength division multiplexers. We demonstrate high-purity energy-time entanglement, i.e., free of photonic noise, with near perfect raw visibilities ($>$~98\%) between various channel pairs in the telecom C-band. Such a compact source stands as a path towards more complex quantum photonic circuits dedicated to quantum communication systems.