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The results of work on a hybrid material composed of a tellurite glass rod doped with submicron diamonds containing nitrogen‐vacancy‐nitrogen and paramagnetic nitrogen‐vacancy color centers are presented. The reported results include details on tellurite glass and cane fabrication, confocal and wide‐field imaging of the submicron diamond distribution in their volume, as well as on the spectroscopic characterization of their fluorescence and optically detected magnetic resonance measurements of magnetic fields and temperatures. Magnetic fields up to 50 G were examined with a sensitivity of 10−5 T Hz−1/2$^{-1/2}$, whereas temperature measurements are simultaneously performed with a sensitivity of 2.2 K Hz−1/2 within the 8 K range at room temperature. In that way, the suitability of such systems for fiber magneto‐ and thermometry with a reasonable performance are already demonstrated in the form of glass rods. At the same time, the rods constitute an interesting starting point for further processing into photonic components such as microstructured fibers or fiber tapers for the realization of specialized sensing modalities. [ABSTRACT FROM AUTHOR]

We present a design for a slot-bridge nanobeam cavity that supports ultrahigh Q/V and optimized far-field emission pattern, and operates at the zero-phonon transition (637nm) of the nitrogen-vacancy color centers in diamond. The slot-bridge cavity is formed by introducing a diamond bridge at the center of the air region of a slotted cavity. As a result of the boundary condition on the parallel component of the electric field, the electric field in the bridge region is the same as that in the slot. This results in a further reduction of the mode volume. Optimized slot-bridge cavities with a calculated Q factor of 6×106 and mode volume of Veff=0.28(λ/n)3have been realized. In comparison to nanobeam cavities, the mode volume is reduced by a factor of 139. The far-field pattern of a slot-bridge cavity is optimized by using the band folding method and by adding small air-slot extensions to the two closest air-holes surrounding the cavity. A high Q of 9.8×105 and a small mode volume of Veff=0.011(λ/n)3 is realized for this design. Therefore, this type of cavities would allow for the realization of efficient single-photon sources. Our results are important for fundamental studies, like cavity quantum electrodynamics, as well as applications in quantum information processing based on diamond where high quality-factor and ultrasmall mode volume are required.

Implementing the modern technologies of light-emitting devices, light harvesting, and quantum information processing requires the understanding of the structure-function relations at spatial scales below the optical diffraction limit and time scales of energy and information flows. Here, we distinctively combine cathodoluminescence (CL) with ultrafast electron microscopy (UEM), termed CL-UEM, because CL and UEM synergetically afford the required spectral and spatiotemporal sensitivities, respectively. For color centers in nanodiamonds, we demonstrate the measurement of CL lifetime with a local sensitivity of 50 nm and a time resolution of 100 ps. It is revealed that the emitting states of the color centers can be populated through charge transfer among the color centers across diamond lattices upon high-energy electron beam excitation. The technical advance achieved in this study will facilitate the specific control over energy conversion at nanoscales, relevant to quantum dots and single-photon sources.

• A slot-bridge nanobeam cavity that supports ultrahigh Q/V and optimized far-field emission pattern is realized in diamond. • An ultrahigh Purcell factor of 1.8 × 10 4 is predicted for this type of cavities. • The far-field radiation pattern is optimized by utilizing the band folding method and by adding small air-slot extensions to the two closest air-holes surrounding the cavity. A high Q of 9.8 × 10 5 and a small mode volume of V eff = 0.011 (λ / n) 3 is realized for this design. Therefore, this type of cavities would allow for the realization of efficient single-photon sources. We present a design for a slot-bridge nanobeam cavity that supports ultrahigh Q/V and optimized far-field emission pattern, and operates at the zero-phonon transition (637 nm) of the nitrogen-vacancy color centers in diamond. The slot-bridge cavity is formed by introducing a diamond bridge at the center of the air region of a slotted cavity. As a result of the boundary condition on the parallel component of the electric field, the electric field in the bridge region is the same as that in the slot. This results in a further reduction of the mode volume. Optimized slot-bridge cavities with a calculated Q factor of 6 × 10 6 and mode volume of V eff = 0.28 (λ / n) 3 have been realized. In comparison to nanobeam cavities, the mode volume is reduced by a factor of 139. The far-field pattern of a slot-bridge cavity is optimized by using the band folding method and by adding small air-slot extensions to the two closest air-holes surrounding the cavity. A high Q of 9.8 × 10 5 and a small mode volume of V eff = 0.011 (λ / n) 3 is realized for this design. Therefore, this type of cavities would allow for the realization of efficient single-photon sources. Our results are important for fundamental studies, like cavity quantum electrodynamics, as well as applications in quantum information processing based on diamond where high quality-factor and ultrasmall mode volume are required. [ABSTRACT FROM AUTHOR]

The nitrogen-vacancy (NV) center in 3 C -SiC, the analog of the NV center in diamond, has recently emerged as a solid-state qubit with competitive properties and significant technological advantages. Combining first-principles calculations and magnetic resonance spectroscopy, we provide thorough insight into its magneto-optical properties. By applying resonantly excited electron paramagnetic resonance spectroscopy, we identified the zero-phonon absorption line of the 3 A 2 → 3 E transition at 1289 nm (within the telecom O-band) and measured its phonon sideband, the analysis of which reveals a Huang-Rhys factor of S = 2.85 and a Debye-Waller factor of 5.8%. The low-temperature spin-lattice relaxation time was found to be exceptionally long ( T 1 = 17 s at 4 K). All these properties make NV in 3 C -SiC a strong competitor for qubit applications. In addition, the strong variation of the zero-field splitting in the range 4-380 K allows its application for nanoscale thermal sensing.

On the demand of single-photon entangled light sources and high-sensitivity probes in the fields of quantum information processing, weak magnetic field detection and biosensing, the nitrogen vacancy (NV) color center is very attractive and has been deeply and intensively studied, due to its convenience of spin initialization, operation, and optical readout combined with long coherence time in the ambient environment. Although the application prospect is promising, there are still some problems to be solved before fully exerting its characteristic performance, including enhancement of emission of NV centers in certain charge state (NV - or NV 0 ), obtaining indistinguishable photons, and improving of collecting efficiency for the photons. Herein, the research progress in these issues is reviewed and commented on to help researchers grasp the current trends. In addition, the development of emerging color centers, such as germanium vacancy defects, and rare-earth dopants, with great potential for various applications, are also briefly surveyed., (© 2020 Wiley-VCH GmbH.)

Due to their exceptional optical and magnetic properties, negatively charged nitrogen-vacancy (NV - ) centers in nanodiamonds (NDs) have been identified as an indispensable tool for imaging, sensing and quantum bit manipulation. The investigation of the emission behaviors of single NV - centers at the nanoscale is of paramount importance and underpins their use in applications ranging from quantum computation to super-resolution imaging. Here, we report on a spin-manipulated nanoscopy method for nanoscale resolutions of the collectively blinking NV - centers confined within the diffraction-limited region. Using wide-field localization microscopy combined with nanoscale spin manipulation and the assistance of a microwave source tuned to the optically detected magnetic resonance (ODMR) frequency, we discovered that two collectively blinking NV - centers can be resolved. Furthermore, when the collective emitters possess the same ground state spin transition frequency, the proposed method allows the resolving of each single NV - center via an external magnetic field used to split the resonant dips. In spin manipulation, the three-level blinking dynamics provide the means to resolve two NV - centers separated by distances of 23 nm. The method presented here offers a new platform for studying and imaging spin-related quantum interactions at the nanoscale with super-resolution techniques., Competing Interests: The authors declare no conflict of interest.