A nitrogen vacancy (NV) center in diamond is known as a solid-state spin qubit at room temperature. NV centers coherently coupled by dipole-dipole interactions have a potential to accomplish quantum registers at room temperature. This study reports to develop a phthalocyanine ion implantation technique to fabricate multiple dipole-coupled NV centers. Photon counts and optically detected magnetic resonance spectra show that up to four NV centers were successfully created in a confocal spot. The histogram of photon counts is fitted by a Poisson distribution, and the ratio of multiple NV spots suggests the potential for a five NV centers creation.

Nitrogen vacancy (NV) centers are a major platform for the detection of nuclear magnetic resonance (NMR) signals on the nanoscale. To overcome the intrinsic electron spin lifetime limit in spectral resolution a heterodyne detection approach is widely used. However, application of this technique at high magnetic fields (> 0.1 T) is yet an unsolved problem. Here we introduce a heterodyne detection method utilizing a series of phase coherent electron nuclear double resonance sensing blocks, thus eliminating the need for the application of numerous Rabi microwave pulses in the detection scheme. As a result our detection protocol can be extended to high magnetic fields, which allow chemical shift resolution in NMR experiments. We demonstrate this principle on a weakly coupled 13C nuclear spin in the bath surrounding single NV centers, while comparing the results to existing heterodyne protocols. This work paves the way towards high field nanoscale heterodyne NMR protocols with chemical resolution.