Scalable on-chip integration of diamond color centers for cryogenic quantum photonics

TL;DR

This paper demonstrates the integration of diamond color centers with photonic crystal cavities on a chip, enabling cryogenic operation and Purcell enhancement, advancing scalable quantum photonic systems.

Contribution

It presents a novel chip-integrated diamond photonic crystal cavity with embedded NV centers, achieving cryogenic operation and optical coupling for quantum photonics.

Findings

Successful integration of diamond color centers with photonic cavities on-chip

Observation of Purcell enhancement at cryogenic temperatures

Demonstration of optical fiber coupling for quantum emission

Abstract

Chip integration of quantum emitters is a crucial milestone for scalable quantum photonic information processing. Among optically active defect centers for quantum photonics, diamond color centers are promising because of their long spin coherence times and high photon emission rates. However, for a coherent-photon emission, they typically require a cryogenic environment to protect optical coherence from thermal phonons, which makes chip integration challenging. In this paper, we develop a chip-integrated diamond photonic crystal cavity embedding an ensemble of nitrogen-vacancy (NV) centers. We confirm cryogenic operation by observing Purcell enhancement of NV-center emission via an edge-coupled optical fiber. This result demonstrates successful integration of diamond color centers, a photonic crystal cavity, and an optical waveguide-fiber package, representing a key step toward scalable diamond-based quantum communication platforms.