Towards quantum sensing at megabar pressures using nitrogen vacancy centers in diamond

The nitrogen vacancy (NV) color center in diamond has emerged as a robust and versatile sensor for a wide range of applications. The recent incorporation of NV centers into diamond anvil cells - the workhorse technology of high pressure science - has enabled the direct imaging of pressure-driven phenomena. In particular, by implanting a shallow layer of NV centers near the anvil cell's culet, one can map the magnetic field vector and the stress tensor with diffraction limited spatial resolution. Despite this progress, a number of challenges remain. Most importantly, prior experiments suggest that NV sensing cannot be performed above \textasciitilde 60 GPa of pressure owing to a sharp reduction of the NV center's contrast as a function of increasing pressure. To this end, we introduce a new approach that enables NV spectroscopy to be performed at well above 100 GPa (megabar) pressures, opening the door for the exploration of high-temperature, pressure-induced superconductivity in the hydrides.