Ultrahigh Vacuum Surface Chemistry for Nanoscale Sensors in Diamond

Abstract

Shallow nitrogen vacancy (NV) centers in diamond are actively explored for quantum sensing applications due to their high sensitivity and nanoscale resolution. However, the diamond surface can host contaminants and defects that give rise to magnetic noise and NV charge state instability. To prepare pristine diamond surfaces and systematically study the surface noise, we have constructed a novel cluster tool combining surface preparation and spectroscopy with cryogenic, confocal microscopy of single NV centers inside the same ultrahigh vacuum (UHV) environment. The UHV confocal microscope chamber allows for high NA imaging, high Rabi frequency microwave driving, and precise magnetic field alignment. Using in situ annealing, we isolate the contribution of adventitious carbon to magnetic noise. We are also able to study surface terminations that are unstable in ambient conditions, allowing us to design new surfaces to enable state-of-the-art nanoscale quantum sensors. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0018978, the NSF under the CAREER program (Grant No. DMR- 1752047), and the DARPA DRINQS program (Agreement No. D18AC00015). We also acknowledge the support from Princeton Imaging and Analysis Center.