Enhanced metrology using preferential orientation of nitrogen-vacancy   centers in diamond
  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 possible 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. 
L. M. Pham, N. Bar-Gill, D. Le Sage, A. Stacey, M. Markham, D. J.   Twitchen, M. D. Lukin, R. L. Walsworth
cond-mat.mes-hall