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The effect of a magnetic field on the luminescence from an ensemble of NV-centers in diamond was studied experimentally and theoretically. It was found that the intensity of infrared luminescence associated with transitions between singlet levels of NV-centers showed a pronounced increase in a near-zero magnetic field. The influence of the power and polarization of the laser radiation on the amplitude and shape of the revealed local maximum in the IR-luminescence of NV-centers was investigated. An eight-level photophysical model of an NV-center in the presence of an arbitrarily directed magnetic field was constructed and used as a basis to calculate the intensity of the luminescence emitted by an ensemble of NV-centers in both the visible and infrared spectral regions. It was shown that a phenomenological allowance for cross relaxation of NV-centers between each other and with other diamond paramagnetic centers within the framework of this model allows the experimentally observed fluorescence features of an ensemble of NV-centers in the presence of weak magnetic fields to be described. [ABSTRACT FROM AUTHOR]

One of the most promising platforms to implement quantum technologies are coupled electron-nuclear spins in solids in which electrons can play a role of "fast" qubits, while nuclear spins can store quantum information for a very long time due to their exceptionally high isolation from the environment. The well-known representative of such systems is the "nitrogen-vacancy" (NV) center in diamond coupled by a hyperfine interaction to its intrinsic 1 4 N/ 1 5 N nuclear spin or to 1 3 C nuclear spins presenting in the diamond lattice. More recently, other paramagnetic color centers in diamond have been identified exhibiting even better characteristics in comparison to the NV center. Essential prerequisite for a high-fidelity spin manipulation in these systems with tailored control pulse sequences is a complete knowledge of hyperfine interactions. Development of this understanding for one of the new color centers in diamond, viz., neutral "silicon-vacancy" (SiV0) color center, is a primary goal of this paper, in which we are presenting preliminary results of computer simulation of spatial and hyperfine characteristics of SiV0 center in H-terminated clusters C 8 4 [SiV0]H 7 8 and C 1 2 8 [SiV0]H 9 8 . [ABSTRACT FROM AUTHOR]

We predict the characteristics of hyperfine interactions (hfi) for a number of electron-nuclear spin systems NV-13C in diamonds grown by seeding approach from the specific isotopic aza-adamantane or methyl-aza-adamantane molecules differing in 13C position in the precursor as well as in the orientation of the NV center in the post-obtained diamond. For the purpose we have used the spatial and hfi data simulated previously for the cluster C510[NV]–H252. The data obtained can be used to identify (and correlate with the precursor used) the specific NV-13C spin system by measuring the hfi-induced splitting in optically detected magnetic resonance spectra being characteristic for the NV-13C system. [ABSTRACT FROM AUTHOR]

The "germanium-vacancy" (GeV) center in diamond can be used as Temperature Sensors. The idea of GeV-based thermometry is based on optical measurements of the spectral shift of the zero-phonon line and its spectral width as a function of temperature changes. At the same time optical characteristics of GeV center which is located near-surface could be modified by formation of defect states in the band gap based on surface impurities and dangling bonds. The electronic structure of the GeV center determines its optical properties. The goal of this study was to investigate comparatively the geometric characteristics and electronic structure of the GeV center in the volume and near-surface (100) of nanodiamond in cluster approximation. It was shown for the first time that formation of isolated dangling bond on the (100) diamond surface leads to formation of unoccupied state in the band gap in vicinity of 1 eV, which is located on the distance of 1.9 eV of conduction band edge. This state in the band gap may influence optical properties of GeV in diamond. [ABSTRACT FROM AUTHOR]

Zero-phonon-line (ZPL) emission of nitrogen vacancies (NVs) is coupled to the guided modes of solid- and hollow-core nanodiamond-doped photonic-crystal fibers (PCFs). Both types of PCFs are tailored toward enhancing ZPL emission coupling to the fiber modes. In solid-core PCFs, this involves enhancing the evanescent field of the waveguide modes supported by an ultrasmall fiber core. In hollow-core PCFs, the NV emission spectrum is matched with the transmission band of the fiber, controlled by the photonic bands of the fiber cladding. [ABSTRACT FROM AUTHOR]