Quantum metrology enables some of the world's most sensitive measurements. When applied to biophysical systems, diamond-based quantum sensors have the potential to probe processes that cannot be accessed by conventional technologies. Examples of such processes range from cancer research to neuroscience to developmental biology. However, interfacing coherent qubit sensors with fragile biological target systems has remained an outstanding challenge that has severely limited applications. In this talk, I will discuss a novel approach that combines single-molecule biophysics technology with quantum engineering to interface intact biomolecules on a diamond quantum sensor without impacting qubit coherence and bio-functionality.

In a second part, I will discuss our recent work on engineering highly coherent quantum sensors based on diamond nanocrystal. Such nanosensors can readily be taken up by cells and integrated into intact organisms. However, coherence in these nanocrystal sensors is limited by surface noise, which severely reduces the sensor’s sensitivity. In our work we developed a new approach to engineer spin coherence in core-shell nanostructures which leads to a 50-fold improvement in qubit sensitivity. Finally, potential future applications of quantum sensing to biophysical and diagnostics will be discussed.