ИСТИНА

The precise knowledge of the position of single-photon emitters, such as e.g. colour centres in diamond, below the limit imposed by optical fluorescence microscopy is of great importance to test the fabrication of strongly - coupled single - photon emitters for entanglement experiments. Several methods permitting to overcome the diffraction limit in optical microscopy are nowadays available, such as e.g. STimulated Emission Depletion (STED [1]) and Ground State Depletion (GSD,[2])and so on: possible complications for these techniques are the use of doughnut - shaped illumination beams and the high pump intensities required. For e xhaustive reviews of the optical techniques able to beat the diffraction limit see ref.[3,4]. In this talk we present an experiment exploiting the photon anti-bunching behaviour of single photon emitters to enhance the resolution of optical fluorescence microscopy of single colour centres in diamond [5,6]. Optical microscopy images of colour centres in bulk diamond grown exploiting Chemical Vapour Deposition (CVD) techniques were acquired on a pixel-by - pixel basis using a laser scanning confocal microscope. Together with the direct measurement of the numbers of detected photon, we show that by acquiring higher - order autocorrelation function (g(n)) - exploiting, e.g., a detector tree [7] or, equivalently, an higher order Hanbury-Brown-Twiss interferometer-resolution enhancement is achieved[8]. Results show an increase in lateral resolution in agreement with theory that predicts a narrowing of the point spread function proportional to the square root of the highest order of the autocorrelation function measured [8].