A scalable photonic quantum interconnect platform

TL;DR

This paper presents a scalable platform for integrating diamond-based quantum memories with photonic structures, enabling high-yield fabrication and strong photon-memory coupling for quantum networking applications.

Contribution

It introduces a wafer-scale processing technique for thin-film diamond with high yield, deterministic membrane transfer, and reliable integration of photonic cavities with quantum memories.

Findings

Achieved near-unity yield in wafer-scale diamond membrane processing.

Demonstrated strong coupling of SiV centers to photons with high cooperativity.

Enabled scalable fabrication of photonic crystal cavities across multiple membranes.

Abstract

Many quantum networking applications require efficient photonic interfaces to quantum memories which can be produced at scale and with high yield. Synthetic diamond offers unique potential for the implementation of this technology as it hosts color centers which retain coherent optical interfaces and long spin coherence times in nanophotonic structures. Here, we report a technique enabling wafer-scale processing of thin-film diamond that combines ion implantation and membrane liftoff, high-quality overgrowth, targeted color center implantation, and serial, high-throughput thermocompression bonding with yields approaching unity. The deterministic deposition of thin diamond membranes onto semiconductor substrates facilitates consistent integration of photonic crystal cavities with silicon-vacancy (SiV) quantum memories. We demonstrate reliable, strong coupling of SiVs to photons with cooperativities approaching 100. Furthermore, we show that photonic crystal cavities can be reliably fabricated across several membranes bonded to the same handling chip. Our platform enables modular fabrication where the photonic layer can be integrated with functionalized substrates featuring electronic control lines such as coplanar waveguides for microwave delivery. Finally, we implement passive optical packaging with sub-decibel insertion loss. Together, these advances pave the way to the scalable assembly of optically addressable quantum memory arrays which are a key building block for modular photonic quantum interconnects.