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We describe a technique for fabricating micro- and nanostructures incorporating fluorescent defects in diamond with a positional accuracy better than hundreds of nanometers. Using confocal fluorescence microscopy and focused ion beam etching, we initially locate a suitable defect with respect to registration marks on the diamond surface then etch a structure using these coordinates. We demonstrate the technique by etching an 8 μm diameter hemisphere positioned with single negatively charged nitrogen-vacancy defect lies at its origin. Direct comparison of the fluorescence photon count rate before and after fabrication shows an eightfold increase due to the presence of the hemisphere. [ABSTRACT FROM AUTHOR]

We report on the noise spectrum experienced by few nanometer deep nitrogen-vacancy centers in diamond as a function of depth, surface coating, magnetic field and temperature. Analysis reveals a double- Lorentzian noise spectrum consistent with a surface electronic spin bath in the low frequency regime, along with a faster noise source attributed to surface-modified phononic coupling. These results shed new light on the mechanisms responsible for surface noise affecting shallow spins at semiconductor interfaces, and suggests possible directions for further studies. We demonstrate dynamical decoupling from the surface noise, paving the way to applications ranging from nanoscale NMR to quantum networks. [ABSTRACT FROM AUTHOR]

Nanometer-sizeddiamonds containing nitrogen-vacancy defect centers(NV) are promising nanosensors in biological environments due to theirbiocompatibility, bright fluorescence, and high magnetic sensitivityat ambient conditions. Here we report on the detection of ferritinmolecules using magnetic noise induced by the inner paramagnetic ironas a contrast mechanism. We observe a significant reduction of bothcoherence and relaxation time due to the presence of ferritin on thesurface of nanodiamonds. Our theoretical model is in excellent agreementwith the experimental data and establishes this method as a novelsensing technology for proteins. [ABSTRACT FROM AUTHOR]