We demonstrate preferential orientation of nitrogen-vacancy (NV) color centers along two of four possible crystallographic axes in diamonds grown by chemical vapor deposition on the {100} face. We identify the relevant growth regime and present a pos
sible explanation of this effect. We show that preferential orientation provides increased optical read-out contrast for NV multi-spin measurements, including enhanced AC magnetic field sensitivity, thus providing an important step towards high fidelity multi-spin-qubit quantum information processing, sensing and metrology.
We demonstrate a method of imaging spatially varying magnetic fields using a thin layer of nitrogen-vacancy (NV) centers at the surface of a diamond chip. Fluorescence emitted by the two-dimensional NV ensemble is detected by a CCD array, from which
a vector magnetic field pattern is reconstructed. As a demonstration, AC current is passed through wires placed on the diamond chip surface, and the resulting AC magnetic field patterns are imaged using an echo-based technique with sub-micron resolution over a 140 mu m x 140 mu m field of view, giving single-pixel sensitivity ~100 nT/sqrt{Hz}. We discuss ongoing efforts to further improve sensitivity and potential bioimaging applications such as real-time imaging of activity in functional, cultured networks of neurons.
