A compact, integrated silicon device for the generation of spectrally-filtered, pair-correlated photons

TL;DR

This paper presents a silicon photonic crystal device that efficiently generates spectrally-filtered, pair-correlated photons with high pump suppression, suitable for integrated quantum photonics.

Contribution

The authors design a symmetry-protected photonic crystal cavity that achieves near-perfect pump suppression and high photon generation efficiency on-chip.

Findings

Achieves close to 40 dB pump suppression despite fabrication disorder.

High quality factors and small mode volumes enhance photon generation efficiency.

Design is compatible with CMOS fabrication for integrated quantum applications.

Abstract

The third-order non-linearity of silicon gives rise to a spontaneous four-wave mixing process in which correlated photon pairs are generated. Sources based on this effect can be used for quantum computation and cryptography, and can in principle be integrated with standard CMOS fabrication technology and components. However, one of the major challenges is the on-chip demultiplexing of the photons, and in particular the filtering of the pump power, which is many orders of magnitude larger than that of the signal and idler photons. Here, we propose a photonic crystal coupled-cavity system designed so that the coupling of the pump mode to the output channel is strictly zero due to symmetry. We further analyze this effect in presence of fabrication disorder and find that, even then, a pump suppression of close to 40 dB can be achieved in state-of-the art systems. Due to the small mode volumes and high quality factors, our system is also expected to have a generation efficiency much higher than in standard micro-ring systems. Those two considerations make a strong case for the integration of our proposed design in future on-chip quantum technologies.