International Exchange Award – Tin-vacancy centres in diamond with integrated photonics for quantum networking

From left to right: David Starling (MIT), Niels Timmerman (Cambridge), Niamh Mulholland (Cambridge), and Ryan Murphy (MIT)

Niels Timmerman a PhD student at the University of Cambridge was awarded an M4QN international exchange award to visit MIT Lincoln Laboratory. The visit took place from 05-12 April 2025.

Tin-vacancy centres in diamond with integrated photonics for quantum networking

The exchange enabled in-person collaboration on quantum networking with tin-vacancies in diamond at the Massachusetts Institute of Technology and MIT Lincoln Laboratory. The collaboration between the University of Cambridge and MIT aims to enable scalable quantum memories by using tin-vacancy centres, which have excellent optical and spin properties, in an integrated photonic silicon nitride chip. The chip allows all-fibre interfacing with the emitter, resulting in unmatched ease of access and implementation, without the need for complex and bulky optical microscopes. The tin vacancy colour centre itself also has properties that help with scalability, such as operating at higher cryogenic temperatures and being resistant to first order electrical noise. In Cambridge, they have demonstrated that tin is a great quantum emitter, while the team at MIT has shown great results with silicon vacancies and their packaged module. This visit provided a significant step forward to using this photonics platform for tin vacancies in Cambridge. Spending time in their laboratories has been massively useful to discuss our different approaches, understanding the development of the integrated photonic chip, and aligning on practical considerations. Building up a quantum networking experiment is a complicated task, so being in the laboratory in person has brought experience that is unmatched by a videocall. Thanks to this exchange, we were able discuss the learnings that the MIT team took from research on the packaged photonic module with silicon vacancy centres and translate them into improvements to our approach with tin.

Benefits to the UK materials and quantum community

This project brings together expertise from MIT, MIT Lincoln Laboratory, and the University of Cambridge to develop long-lived, highly accessible quantum memories in a scalable platform. We have promising results on the spin coherence times and indistinguishability of photons emitted by the tin-vacancy centre in diamond, and the integration of the emitter in integrated photonics platform is a big step toward bringing this technology to a deployed, long-range, UK-wide quantum network. Efforts towards long-range remote entanglement networks are strongly aided by this technology, specifically because it has been engineered to be easier to implement at remote sites without laboratory-grade equipment. Our focus is now on demonstrating remote entanglement with this platform, which is a direct result of this exchange, thanks to M4QN. The University of Cambridge has long been at the forefront of colour centre research, and this project and collaboration will accelerate the transition of this technology from the lab into the real world.

Visit Outcomes

Niels writes “The outcome is twofold. Firstly, the visit allowed us to refine how we embed the photonic device into our laboratory. Because of this, the packaged tin-vacancy was successfully implemented at the University of Cambridge, and the first results have been very promising. The team is working on a paper in a high impact journal, together with MIT. Secondly, the knowledge gained from the exchange has led to the development of a second-generation photonic device with even higher performance, in the same collaboration.”