Probing surface noise with depth-calibrated spins in diamond
  Sensitive nanoscale magnetic resonance imaging (MRI) of target spins using nitrogen-vacancy (NV) centers in diamond will require a quantitative understanding of dominant noise at the surface. We probe this noise by applying dynamical decoupling to shallow NVs at calibrated depths. Results support a model of NV dephasing by a surface bath of electronic spins having a correlation rate of 200 kHz, much faster than that of the bulk N spin bath. Our method of combining nitrogen delta-doping growth and nanoscale depth imaging paves a way for studying spin noise present in diverse material surfaces. 
Bryan A. Myers, Matthieu C. Dartiailh, Kenichi Ohno, Ananda Das, David   D. Awschalom, Ania C. Bleszynski Jayich
cond-mat.mes-hall