Lab exchange grant: Quantum Sensing in two-dimensional materials – From large spin ensembles to single spin defects

Charlie Patrickson PhD student at The University of Exeter was awarded an M4QN laboratory exchange award to visit Hannah Stern at the University of Oxford. The visit took place from 17th – 28th March 2025.

The purpose of the visit

The visit had the central aim of facilitating knowledge exchange between Prof. Isaac Luxmoore’s group at the University of Exeter where Charlie is based, and Prof. Stern’s group in the materials department at the University of Oxford.

Charlie writes ” We develop quantum sensing protocols using spin defects in two dimensional materials. To increase the signal-to-noise ratio of our sensors we use large spin ensembles. However, this compromises on spatial resolution as the readout process becomes diffraction limited. In contrast, single defects in two-dimensional materials could combine nanoscale sensor-source distances with nanoscale spatial resolution. Professor Hannah Stern has pioneered the development of single defects in the two-dimensional van der Waals material hexagonal boron nitride.
The visit has allowed me to develop an understanding of critical experimental differences between using well-established defect ensembles and unidentified single defects. For the latter, Prof Stern’s group have developed considerable expertise regarding the stringent requirements on experimental stability and defect characterisation. The group provided an overview of their experimental setup, after which I shadowed PhD students Finlay Campbell and Sivasruthi Kesavan whilst they built an experimental setup capable of single defect characterisation. It was clear that the stability of the setup was of critical importance; observing how they identified and navigated these experimental challenges was incredibly valuable. I was also invited to present my own research to the department.”

Benefits to the UK materials and quantum community

Charlie writes “These types of spin system are exceptionally sensitive magnetometers. If successfully applied to nanoscale magnetometry they could have a considerable impact on materials development, with near term efforts focusing on magnetic resonance imaging and probing low dimensional condensed matter systems. Effective implementation will benefit significantly from a collaborative effort that encompasses all aspects of device performance. This visit laid the foundations for this kind of approach, with Prof. Stern’s group focusing on materials research, where they have led the development of new defects that are robust to magnetic noise, and our research into targeted measurement protocols, using advanced spin control techniques to enhance sensing performance. Having the opportunity to share this expertise will accelerate the development of nanoscale magnetometry, and help to solidify the UK’s position in the field. Looking further ahead, both robust single defects and advanced spin control protocols have direct relevance in applications that require quantum memories, such as quantum networking.

It was clear that the materials department in Oxford is home to a flourishing community of quantum researchers, and I found Prof. Stern’s group and the wider department to be exceptionally welcoming. Throughout the trip I was invited to attend group meetings, research seminars and neighbouring lab visits. Additionally, my own presentation was well attended by neighbouring research groups, with engaging and insightful questions offering refreshing perspectives on our work. This kind of exposure to broader research themes is incredibly valuable, helping to generate new ideas and collaborative links.”

Visit outcomes

The trip strengthened ties within the UK’s quantum materials community and allowed the groups involved to establish the foundations of an ongoing knowledge exchange and collaboration. Prof. Stern generously extended an open invitation to return in the future. Charlie will build on the experience with regular contact and hopes to plan further work packages once initial results are established.