Alexandre Tallaire, IRCP, Chimie ParisTech, Paris and LSPM, CNRS, Villetaneuse, France

The negatively charged nitrogen-vacancy centre (NV) in diamond is a point-like defect that has focused a lot of attention in the past few years due to a number of emerging applications in quantum technologies, in particular for magnetic sensing. It is a single photon emitter with good photostability and which electronic spin state can be optically read-out and manipulated leading to exceptionally long coherence time even at room temperature. Harnessing the outstanding properties of NVs mainly relies on the progresses obtained in the synthesis of high quality and purity diamond material using the microwave plasma assisted chemical vapour deposition technique (MPACVD). Individual or ensembles of NV centres can be produced by nitrogen implantation or through direct in situ creation by adding a N-containing precursor. Both approaches have some advantages in terms of spatial localisation, coherence time or defect preferential orientation. Controlling defects and/or the spin bath surrounding the NV centres is crucial to obtaining good spin properties. All those requirements are very challenging and are setting an increasing pressure to the diamond synthesis capabilities by MPACVD. In this talk the growth of nitrogen-doped CVD diamond single crystals by MPACVD will be described. Special emphasis will be given to the control of the orientation and localization of NV centres and the optimization of their density and stability.

High-purity single crystal CVD diamonds produced at LSPM – Localized luminescent NV pattern in diamond crystal – Spin echo measurement on isolated NVs allowing extracting their coherence time T₂