Scalable integration of long-lived quantum memories into a photonic circuit

TL;DR

This paper presents a scalable photonic circuit integrating long-lived quantum memories using diamond nitrogen vacancy centers, achieving high coupling efficiency and long coherence times, advancing quantum information processing.

Contribution

It demonstrates the deterministic integration of stable quantum memories into silicon nitride photonic circuits with high yield and efficiency, enabling scalable quantum technologies.

Findings

Quantum memories with up to 120 μs coherence time.

High coupling efficiency with > 1 million counts per second.

Near unity yield in assembling multiple quantum memories.

Abstract

We demonstrate a photonic circuit with integrated long-lived quantum memories. Pre-selected quantum nodes - diamond micro-waveguides containing single, stable, and negatively charged nitrogen vacancy centers - are deterministically integrated into low-loss silicon nitride waveguides. Each quantum memory node efficiently couples into the single-mode waveguide (> 1 Mcps collected into the waveguide) and exhibits long spin coherence times of up to 120 {\mu}s. Our system facilitates the assembly of multiple quantum memories into a photonic integrated circuit with near unity yield, paving the way towards scalable quantum information processing.