Optimization of single crystalline all diamond scanning probes for quantum sensing applications

Moore's Law demands for innovation not only to solve the question of how to store even more information on even smaller areas but also in how to access this information. Both problems make point defects in solid-state systems very interesting. Color centers in diamond are one of these atom-like systems. Their electronic spins can be used as a versatile sensor or quantum storage. These sensors live up to their full potential when combined with a scanning technique as atomic force microscopy (AFM). The precise control of the position combined with an atom-sized light source or sensor opens up various possibilities. The main struggles encountered by the field so far are the difficulty of retaining the crystal quality of bulk diamond and simultaneously have a sharp tip to get the best topological feedback possible. In our work, we present three different avenues to tackle this. We conduct a study of the cause of decoherence in plasma etched nanostructures and test different treatments to reduce the effect. We test a novel method to stabilize an alternative color center believed to be less sensitive to electric field noise. Furthermore, we explore a new approach combining top-down fabrication and bottom-up overgrowth to get sharp tips with good crystal quality. The combination of the individual avenues has the potential to bring the sensing and imaging capabilities of color center-based sensing to the next level.