High-precision electron-spin sensing with ensembles of nitrogen-vacancy centers in diamond

Abstract

This thesis describes physical background and an experimental realization of a bulk diamond magnetic field and temperature sensor. The sensing is done using continuous-wave electron-spin resonance spectra of nitrogen-vacancy centers in diamond. Experiments were performed using a light-trapping diamond waveguide sample, with which we estimate to address 10¹³ nitrogen-vacancy centers simultaneously. We derive energy level structure of a nitrogen-vacancy center and recover resonant frequencies of the ESR spectrum. Using the Lindblad master equation, we model ESR line-shape and for the first time consider the influence of infrared driving on the ESR contrast. Both continuous-wave and pulsed sensing protocols are described, and a novel reference-free temperature sensing scheme is proposed. In addition to building a laboratory setup for sensing, we discuss how to miniaturize the setup components and make an on-chip diamond sensor. In particular, we optimize the on-chip fluorescence collection apparatus. Finally, using the built laboratory setup, we demonstrate magnetic field sensitivity floor on the order of 1 nT/Hz 1/2 and temperature sensitivity floor of 0.3 mK/Hz 1/2.