  Abstract Applications of nitrogen-vacancy (NV) centers in diamond in quantum
technology have attracted considerable attention in recent years. Deterministic
generation of ensembles of NV centers can advance the research on quantum
sensing, many-body quantum systems, multipartite entanglement and so on. Here
we report the complete process of controlled generation of NV centers in
diamond as well as their characterisation: growing diamond films through
chemical vapor deposition (CVD), ion implantation and spectroscopic
characterization of the defect centers using a confocal microscope. A
microwave-assisted CVD set-up is presented which we constructed for the
preparation of single-crystalline homoepitaxial diamond films. The films were
prepared with minimized nitrogen concentration, which is confirmed through
photoluminescence measurements. We demonstrate an in situ ultra high vacuum
(UHV) implantation and heating process for creation of NV centers using a novel
experimental set-up. For the first time hot implantation has been shown which
prevents surface charging effects. We do not observe graphitization due to UHV
heating. By optimizing the implantation parameters it has been possible to
implant NV centers in a precise way. We present large area mapping of the
samples to determine the distribution of the centers and describe the
characterization of the centers by spectroscopic techniques. Reducing the
decoherence caused by environmental noise is of primary importance for many
applications in quantum technology. We demonstrate improvement on coherence
time T_{2} of the NV spins by suppression of their interaction with the
surrounding spin-bath using robust dynamical decoupling sequences.
