UC Berkeley

Pressure alters all properties of matter. The development of the diamond anvil cell enables the exploration of high pressure phenomena in tabletop experiments. This thesis introduces an optical sensing platform based on nitrogen-vacancy color centers embedded into the culet (tip) of a diamond anvil. The micron-scale spatial resolution and high sensitivity of this platform to stress, magnetic and electric fields opens the door to a hitherto unexplored range of experiments. We demonstrate the versatility of this platform through several applications. In the context of stress, we demonstrate imaging of all normal and shear components of the stress tensor, which enables us to probe the accumulation and dissipation of shear stresses of chrysotile serpentine (Mg_3(Si_2 O_5)(OH)_4) undergoing brittle failure. In the context of magnetism, we demonstrate imaging of vector magnetic fields under gigapascal pressure, enabling measurement of the \alpha-->\epsilon transition in elemental iron as well as the complex pressure-temperature phase diagram of elemental gadolinium. We further extend these magnetic imaging capabilities to probe the pressure-induced demagnetization of 4C monoclinic pyrrhotite (Fe_7 S_8), an iron sulfide mineral found in the Earth's crust as well as in Martian and chondritic meteorites. In the context of electric fields, we show that a spectral feature commonly observed in NV centers originates from the local charge environment of the diamond lattice, and we utilize this understanding to image individual electronic charges with nanometer precision. We extend this understanding to the NV center orbital excited state, whose strong coupling to electric fields enables a protocol that enhances measurement sensitivity by several orders of magnitude. Finally, motivated by the sensitivity of NV centers to electric noise, we theoretically consider polarization fluctuations from polar and dielectric materials and show that this electric noise encodes valuable information about dielectric properties over a range of frequencies and length scales.