Coherence of Nitrogen-Vacancy Electronic Spin Ensembles in Diamond

Abstract

We present an experimental and theoretical study of electronic spin decoherence in ensembles of nitrogen-vacancy (NV) color centers in bulk high-purity diamond at room temperature. Under appropriate conditions, we find ensemble NV spin coherence times ((T_2)) comparable to that of single NV with (T_2>600 \mu s) for a sample with natural abundance of (^{13})C and paramagnetic impurity density ∼1015 cm(^{−3}). We also observe a sharp decrease in the coherence time with misalignment of the static magnetic field relative to the NV electronic spin axis, consistent with theoretical modeling of NV coupling to a (^{13})C nuclear-spin bath. The long coherence times and increased signal-to-noise provided by room-temperature NV ensembles will aid many applications of NV centers in precision magnetometry and quantum information.