Physics Colloquium: Paul Stevenson, Northeastern University

About

Small fields, big challenges: spectroscopy

and imaging with NV centers

Nitrogen Vacancy (NV) centers in diamond are now a workhorse platform for solid-state quantum sensing. As the technology matures, attention is shifting from proof-of-concept demonstrations toward practical measurements where sensitivity, spatial resolution, and sensor integration are paramount. In many of these applications - from nanoscale imaging to molecular spectroscopy - the relevant signals are surprisingly weak, often at the edge of what current NV sensors can detect. Understanding the fundamental limits and developing strategies to work at these limits is essential for expanding the reach of NV-based sensing.

In this talk, I will discuss recent progress from our lab in working at the limits of NV-based detection across two fronts. First, I will present our work on imaging nanoscale magnetic textures in multiferroic materials, where the sub-diffraction resolution of NV centers reveals new topological features. Second, I will discuss the diverse magnetic signals present in biological systems and show how we can probe the probe the spin configuration in metalloproteins. These challenges drive new approaches to measurement and analysis that will be essential as NV centers and other quantum defects move toward more demanding applications.