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The results of growing multilayered nitrogen-doped nanostructures that have the form of periodically arranged nanometer-thick nitrogen-containing layers in a single-crystal CVD diamond are presented. The possibility of creating nitrogen-doped diamond layers with extremely sharp boundaries (less than 1 nm) is demonstrated. The photoluminescence study have shown that multilayered structures make it possible to obtain a higher radiation intensity of practically important NV – sites at a spin coherence time close to that for uniformly doped layers with the same concentration of nitrogen.

Creation of localized NV center ensembles, produced by irradiation of CVD diamond with nitrogen doped delta-layer with 200 keV electron beam and the subsequent annealing is demonstrated. Results of optical measurements of activated areas at different irradiation doses are presented. Issues concerning defect formation in diamond lattice during the electron beam impact are discussed.

Properties of silicon-vacancy (SiV) colour centres in ultra-nanosize diamonds are studied. Nanodiamonds are obtained at a high temperature and pressure, which induced transformations in mixtures of organic and hetero-organic compounds without metal-catalysts. The size distribution of grown nanodiamonds is determined by the methods of transmission electron microscopy and atomic-force microscopy, as well as by using the model of phonon spatial localisation. In addition, Raman spectra of various nanodiamonds and luminescence properties of SiV-centres are investigated.

In this work, we study the optical properties of NV centers in detonation nanodiamonds and SiV centers in HPHT nanodiamonds with the size about 10 nm. We experimentally measure the size of nanodiamonds with color centers on the substrate. We demonstrate that detonation nanodiamonds have tendency to aggregate, whereas HPHT diamond may lay as single digit crystals. In despite of the aggregation and ultrasmall size, these nanodiamonds still contain bright single color center with antibunching photon statistics.

A microwave antenna configuration shaped as coaxial resonant coils is proposed for exciting magnetic dipole transitions of the optical ground state of the nitrogen—vacancy color center in diamond. The field within the antenna is simulated, field amplitudes are experimentally measured.

Quickly developing application of nitrogen-vacancy color centers in diamond sets demands on cheap and high optical and spin properties nanodiamonds. Among other types, detonation nanodiamonds are easiest for production but often show no NV color centers inside. In this work we show, that aggregates of detonation nanodiamonds could be as good, or even better in terms of brightness and spin properties, than more expensive single crystal nanodiamonds. This way aggregates of detonation nanodiamonds could efficiently serve as cheap and bright source of single photon radiation or sensitive element of biocompatible sensor.

Ensembles of nitrogen-vacancy color centers in diamond hold promise for ultra-precise magnetometry, competing with superconducting quantum interference device detectors. By utilizing the advantages of dielectric materials, such as very low losses for electromagnetic field, with the potential for creating high Q-factor resonators with strong concentration of the field within it, we implemented a dielectric resonator antenna for coherent manipulation of a large ensemble of nitrogen-vacancy centers in diamond. We reached average Rabi frequency of 10 MHz in a volume of 7 mm3 with a standard deviation of less than 1% at a moderate pump power. The obtained result enables use of large volume low nitrogen-vacancy concentration diamond plates in modern nitrogen-vacancy magnetometers thus improving sensitivity via larger coherence time and higher optical detected magnetic resonance contrast.

Integration of solid-state quantum emitters such as NV center in diamond with tapered optical fiber is demanded by number of applications ranging from sensing and imaging to quantum communications and computations. Nevertheless, utilization of a single NV center coupled with an optical fiber meets significant challenge of fiber fluorescence that can considerably mask emission of the quantum object. In this paper, we analyze main sources of such fluorescence for the case of NV center coupled to tapered single mode optical fiber and discuss possible ways of improving signal to noise ratio in this case.

The nitrogen-vacancy (NV) center in diamond is attracting a lot of attention in quantum information processing community. A spin system in the NV center is positioned in a clean and well-controlled environment. As a result, it shows outstanding performance as quantum memory, even at room temperature, allows for spin control with a single shot optical readout, and offers a possibility of building quantum registers on a single NV center. At low temperature, the NV centers have narrow optical transitions, which enable interfacing between optical photons and the NV center spin states. Recently, the entanglement of two independent NV centers has been demonstrated. This makes the NV center a promising candidate for realization of quantum repeaters. Moreover, the NV centers could be used as sensitive elements of detectors of magnetic or electric fields, temperature etc‥ For all of these applications collection of the light emitted by the NV center is a crucial point. Recent developments in the field of metamaterials allowed creating hyperbolic metamaterials which may provide an efficient interface for coupling light into and out of the NV centers and, in particular, enable a single photon source based on NV. In this work, I will present our work on using CMOS-compatible hyperbolic metamaterials and optical fibers to construct efficient single photon sources and sensing elements using NV centers in diamond.

The sensitivity of magnetic and electric field sensors based on nitrogen-vacancy (NV) center in diamond strongly depends on the available concentration of NV and their coherence properties. Achieving high coherence times simultaneously with high concentration is a challenging experimental task. Here, we demonstrate that by using a temperature gradient method of high-pressure, high-temperature growing technique, one can achieve nearly maximally possible dephasing times, limited only by carbon nuclear spins at low nitrogen concentrations or nitrogen electron spin at high nitrogen concentrations. Hahn-echo T 2 coherence times were also investigated and found to demonstrate reasonable values. Thus, the high-pressure, high-temperature technique is a strong contender to the popular chemical vapor deposition method in the development of high-sensitivity, diamond-based sensors.

Further development of quantum emitter based communication and sensing applications intrinsically depends on the availability of robust single-photon detectors. Here, we demonstrate a new generation of superconducting single-photon detectors specifically optimized for the 500–1100 nm wavelength range, which overlaps with the emission spectrum of many interesting solid-state atom-like systems, such as nitrogen-vacancy and silicon-vacancy centers in diamond. The fabricated detectors have a wide dynamic range (up to 350 million counts per second), low dark count rate (down to 0.1 counts per second), excellent jitter (62 ps), and the possibility of on-chip integration with a quantum emitter. In addition to performance characterization, we tested the detectors in real experimental conditions involving nanodiamond nitrogen-vacancy emitters enhanced by a hyperbolic metamaterial.

In this paper, we experimentally investigate optical and spin properties of NV centers in aggregates of detonation nanodiamonds. We show that despite the small size of nanodiamonds forming the aggregate, the NV centers in these aggregates exhibit spin properties comparable to similar size nanodiamonds grown by other methods, but with brightness enhanced by a factor of 2.