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The elimination of defects from SiC has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because certain SiC defects have electronic states with sharp optical and spin transitions, they are increasingly recognized as a platform for quantum information and nanoscale sensing. Here, we show that individual electron spins in high-purity monocrystalline 4H-SiC can be isolated and coherently controlled. Bound to neutral divacancy defects, these states exhibit exceptionally long ensemble Hahn-echo spin coherence times, exceeding 1 ms. Coherent control of single spins in a material amenable to advanced growth and microfabrication techniques is an exciting route towards wafer-scale quantum technologies. [ABSTRACT FROM AUTHOR]

The negatively charged nitrogen vacancy center (NV) in diamond has generated significant interest as a platform for quantum information processing and sensing in the solid state. For most applications, high quality optical cavities are required to enhance the NV zero-phonon line (ZPL) emission. An outstanding challenge in maximizing the degree of NV-cavity coupling is the deterministic placement of NVs within the cavity. Here, we report photonic crystal nanobeam cavities coupled to NVs incorporated by a delta-doping technique that allows nanometer-scale vertical positioning of the emitters. We demonstrate cavities with Q up to ~24000 and mode volume V ~ 0.47(λ/n)³ as well as resonant enhancement of the ZPL of an NV ensemble with Purcell factor of ~20. Our fabrication technique provides a first step towards deterministic NV-cavity coupling using spatial control of the emitters. [ABSTRACT FROM AUTHOR]

The nitrogen-vacancy (NV) centerin diamond is an attractive platformfor quantum information and sensing applications because of its roomtemperature operation and optical addressability. A major researcheffort focuses on improving the quantum coherence of this defect inengineered micro- and nanoscale diamond particles (DPs), which couldprove useful for high-resolution sensing in fluidic environments.In this work we fabricate cylindrical diamonds particles with finelytuned and highly reproducible sizes (diameter and height ranging from100 to 700 and 500 nm to 2 μm, respectively) using high-purity,single-crystal diamond membranes with shallow-doped NV centers. Weshow that the spin coherence time of the NV centers in these particlesexceeds 700 μs, opening the possibility for the creation ofultrahigh sensitivity micro- and nanoscale sensors. Moreover, theseparticles can be efficiently transferred into a water suspension anddelivered to the region to probe. In particular, we introduce a DPsuspension inside a microfluidic circuit and control position andorientation of the particles using an optical trapping apparatus.We demonstrate a DC magnetic sensitivity of 9 μT/√Hzin fluid as well as long-term trapping stability (>30 h), whichpavesthe way toward the use of high-sensitivity pulse techniques on contactlessprobes manipulated within biological settings. [ABSTRACT FROM AUTHOR]