Solid-state spin defects, such as nitrogen-vacancy centers in diamond, have emerged as powerful platforms for quantum sensing, enabling nanoscale measurements of magnetic fields, temperature, strain, and electric fields at both cryogenic and ambient temperatures.

Some experimental efforts in Singha’s group focus on using these quantum sensors for non-invasive probing of isolated magnetic molecules on surfaces, which are difficult to access with other complementary methods. These efforts naturally require the use of near-surface NV centers (less than 10 nm) to achieve the desired magnetic sensitivity. However, such shallow NV sensors are infamous for often lacking sufficient stability of their optical and spin properties. They take advantage of their UHV experimental conditions to understand the role of the diamond surface in defining these optical and spin properties for shallow NV sensors, as well as to better engineer the diamond surface with desired surface chemistry.

Another aspect of their current research involves two-dimensional mapping of both static and dynamic magnetization profiles of synthetic antiferromagnets, 2D superconductors, and nanoscale devices using a scanning-probe NV magnetometer. The key idea here is to characterize their local nanoscale properties, which are often obscured in conventional transport measurements.
After providing a broad overview of the current research scope in her experimental group, Singha will highlight the challenges and opportunities in this vibrant field of research.