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We experimentally demonstrate quantum enhanced resolution in confocal fluorescence microscopy exploiting the non-classical photon statistics of single nitrogen-vacancy colour centres in diamond.
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We report about the development of a novel method for the fabrication of three-dimensional buried graphitic micropaths in single crystal diamond with the employment of focused MeV ions [1]. The use of implantation masks with graded... more
We report about the development of a novel method for the fabrication of three-dimensional buried graphitic micropaths in single crystal diamond with the employment of focused MeV ions [1]. The use of implantation masks with graded thickness at the sub-micrometer scale allows the formation of conductive channels which are embedded at controllable depths in the insulating matrix. In particular, the modulation of the channels depth at their endpoints allows the surface contacting of the channel terminations with no need of further fabrication stages.
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During the last years, the authors developed innovative diamond-based biosensors for applications in cellular neuroscience. The application of these devices, with embedded graphitic micro-channels, has helped to achieve substantial... more
During the last years, the authors developed innovative diamond-based biosensors for applications in cellular neuroscience. The application of these devices, with embedded graphitic micro-channels, has helped to achieve substantial results in this scientific field. Indeed, for the first time, a correlation between X-rays exposure and the increase of the neurosecretion activity of in vitro cellular samples was demonstrated [1]. Electrons generated by ionizing radiation in target biological samples release their energy, and thus damage the chemical structure of the target sample. In radiation biology, the main effects are given by the interaction with DNA. As a consequence, a series of pathways and systems in the cell are activated to efficiently repair the DNA-base damages, even though the excessive damage could eventually lead to the programmed cellular death (apoptosis). For this reason, measurements of the dose delivered to the irradiated cellular samples are crucial to acquire in...
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We report on the fabrication and characterization of a single-crystal diamond device for the electrical stimula- tion of light emission from nitrogen-vacancy (NV0) and other defect-related centers. Pairs of sub-superficial graphitic... more
We report on the fabrication and characterization of a single-crystal diamond device for the electrical stimula- tion of light emission from nitrogen-vacancy (NV0) and other defect-related centers. Pairs of sub-superficial graphitic micro-electrodes embedded in insulating diamond were fabricated by a 6 MeV C3+ micro-beam irra- diation followed by thermal annealing. A photoluminescence (PL) characterization evidenced a low radiation damage concentration in the inter-electrode gap region, which did not significantly affect the PL features domi- nated by NV centers. The operation of the device in electroluminescence (EL) regime was investigated by ap- plying a bias voltage at the graphitic electrodes, resulting in the injection of a high excitation current above a threshold voltage (~300V), which effectively stimulated an intense EL emission from NV0 centers. In addition, we report on the new observation of two additional sharp EL emission lines (at 563 nm and 580 nm) related to inters...
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Action potential generation is one of the main mechanisms regulating cell excitability and communication. This process consists in a membrane potential variation, induced by the opening and closure of ion channels, which spreads on the... more
Action potential generation is one of the main mechanisms regulating cell excitability and communication. This process consists in a membrane potential variation, induced by the opening and closure of ion channels, which spreads on the plasma membrane. This rapid depolarization is not only a specific communication mechanism between neurons, but it also governs the synaptic transmission, the hormonal release and muscle contraction [1]. In neuroscience, the development of sensors devoted to the detection of these signals is of paramount importance since they would allow performing experiments in which molecular mechanisms or drugs efficacy could be investigated at the cellular level. Diamond-based devices represent a promising solution to this technological demand due to the actracting properties of this material. In this paper we present multi electrode array (MEA) cellular sensors based on embedded graphitic microchannels fabricated by means of MeV ion beam lithography into artifici...
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The possibility of using Nitrogen-vacancy centers in diamonds to measure nanoscale magnetic fields with unprecedented sensitivity is one of the most significant achievements of quantum sensing. Here we present an innovative experimental... more
The possibility of using Nitrogen-vacancy centers in diamonds to measure nanoscale magnetic fields with unprecedented sensitivity is one of the most significant achievements of quantum sensing. Here we present an innovative experimental set-up, showing an achieved sensitivity comparable to the state of the art ODMR protocols if the sensing volume is taken into account. The apparatus allows magnetic sensing in biological samples such as individual cells, as it is characterized by a small sensing volume and full bio-compatibility. The sensitivity at different optical powers is studied to extend this technique to the intercellular scale.
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We present an innovative experimental set-up that uses Nitrogen-Vacancy centres in diamonds to measure magnetic fields with the sensitivity of $\eta =68\pm 3~\mathrm{nT}/\sqrt{\mathrm{Hz}}$ η = 68 ± 3 nT / Hz at demonstrated (sub)cellular... more
We present an innovative experimental set-up that uses Nitrogen-Vacancy centres in diamonds to measure magnetic fields with the sensitivity of $\eta =68\pm 3~\mathrm{nT}/\sqrt{\mathrm{Hz}}$ η = 68 ± 3 nT / Hz at demonstrated (sub)cellular scale. The presented method of magnetic sensing, utilizing a lock-in based ODMR technique for the optical detection of microwave-driven spin resonances induced in NV centers, is characterized by the excellent magnetic sensitivity at such small scale and the full biocompatibility. The cellular scale is obtained using a NV-rich sensing layer of 15 nm thickness along z axis and a focused laser spot of $(10 \times 10)~\mu\mathrm{m}^{2}$ ( 10 × 10 ) μ m 2 in x-y plane. The biocompatibility derives from an accurate choice of the applied optical power. For this regard, we also report how the magnetic sensitivity changes for different applied laser power and discuss the limits of the sensitivity sustainable with biosystem at such small volume scale. As suc...
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We have measured the radiation tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after irradiation in a 50 m pitch strip... more
We have measured the radiation tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after irradiation in a 50 m pitch strip detector fabricated on each diamond sample. We irradiated one group of sensors with 800 MeV protons, and a second group of sensors with 24 GeV protons, in steps, to protons cm−2 and protons cm−2 respectively. We observe the sum of mean drift paths for electrons and holes for both poly-crystalline CVD diamond and single-crystalline CVD diamond decreases with irradiation fluence from its initial value according to a simple damage curve characterized by a damage constant for each irradiation energy and the irradiation fluence. We find for each irradiation energy the damage constant, for poly-crystalline CVD diamond to be the same within statistical errors as the damage constant for single-crystalline CVD diamond. We find the damage constant for diamond irradi...
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Research Interests: Physics, Optics, Microscopy, Medicine, Physical sciences, and 3 moreDiffraction, Autocorrelation, and Confocal
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MeV ion implantation is an effective tool in the micro-fabrication of a vast range of materials [1-5], and in particular it can be effectively adopted to fabricate three-dimensional micro-strucures in single-crystal diamond such as... more
MeV ion implantation is an effective tool in the micro-fabrication of a vast range of materials [1-5], and in particular it can be effectively adopted to fabricate three-dimensional micro-strucures in single-crystal diamond such as waveguides [6,7], photonic structures [8] and micro-mechanical resonators [9,10]. The damage density can be controlled over a broad range by varying several implantation parameters, such as ion species and fluence, resulting in the formation of point defects, in the amorphization and eventually in the permanent graphitization of the pristine crystal upon thermal annealing when a critical damage threshold is reached [11]. In this structural modification process, high spatial resolution in both lateral and depth dimensions is allowed respectively by the availability of focused ion beams and by the peculiar damage density profile of highly energetic ions in matter. In particular, since most of the ion matter nuclear interaction occurs at the end of implanted...
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Single-photon sources are a fundamental element for developing quantum technologies, and sources based on colour centres in diamonds are among the most promising candidates. The well-known NV centres are characterized by several... more
Single-photon sources are a fundamental element for developing quantum technologies, and sources based on colour centres in diamonds are among the most promising candidates. The well-known NV centres are characterized by several limitations, thus few other defects have recently been considered. In the present work, we characterize in detail native efficient single colour centres emitting in the near infra-red in both standard IIa single-crystal and electronic-grade polycrystalline commercial CVD diamond samples. In the former case, a high-temperature annealing process in vacuum is necessary to induce the formation/activation of luminescent centres with good emission properties, while in the latter case the annealing process has marginal beneficial effects on the number and performances of native centres in commercially available samples. Although displaying significant variability in several photo physical properties (emission wavelength, emission rate instabilities, saturation beha...
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We report on the systematic characterization of photoluminescence (PL) lifetimes in NV- and NV0 centers in 2 MeV H+ implanted type Ib diamond samples by means of a time correlated single photon counting (TCSPC) microscopy technique. A... more
We report on the systematic characterization of photoluminescence (PL) lifetimes in NV- and NV0 centers in 2 MeV H+ implanted type Ib diamond samples by means of a time correlated single photon counting (TCSPC) microscopy technique. A dipole-dipole resonant energy transfer model was applied to interpret the experimental results, allowing a quantitative correlation of the concentration of both native (single substitutional nitrogen atoms) and ion-induced (isolated vacancies) PL-quenching defects with the measured PL lifetimes. The TCSPC measurements were carried out in both frontal (i.e. laser beam probing the main sample surface along the same normal direction of the previously implanted ions) and lateral (i.e. laser beam probing the lateral sample surface orthogonally with respect to the same ion implantation direction) geometries. In particular, the latter geometry allowed a direct probing of the centers lifetime along the strongly nonuniform damage profiles of MeV ions in the cry...
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As demonstrated in previous works, implantation with a MeV ion microbeam through masks with graded thickness allows the formation of conductive micro-channels in diamond which are embedded in the insulating matrix at controllable depths... more
As demonstrated in previous works, implantation with a MeV ion microbeam through masks with graded thickness allows the formation of conductive micro-channels in diamond which are embedded in the insulating matrix at controllable depths [P. Olivero et al., Diamond Relat. Mater. 18 (5-8), 870-876 (2009)]. In the present work we report about the systematic electrical characterization of such micro-channels as a function of several implantation conditions, namely: ion species and energy, implantation fluence. The current-voltage (IV) characteristics of the buried channels were measured at room temperature with a two point probe station. Significant parameters such as the sheet resistance and the characteristic exponent (alpha) of the IV power-law trend were expressed as a function of damage density, with satisfactory compatibility between the results obtained in different implantation conditions.
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Single-photon sources represent a key enabling technology in quantum optics, and single colour centres in diamond are a promising platform to serve this purpose, due to their high quantum efficiency and photostability at room temperature.... more
Single-photon sources represent a key enabling technology in quantum optics, and single colour centres in diamond are a promising platform to serve this purpose, due to their high quantum efficiency and photostability at room temperature. The widely studied nitrogen vacancy centres are characterized by several limitations, thus other defects have recently been considered, with a specific focus of centres emitting in the Near Infra-Red. In the present work, we report on the coupling of native near-infrared-emitting centres in high-quality single crystal diamond with Solid Immersion Lens structures fabricated by Focused Ion Beam lithography. The reported improvements in terms of light collection efficiency make the proposed system an ideal platform for the development of single-photon emitters with appealing photophysical and spectral properties.
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We report on the systematic characterization of conductive micro-channels fabricated in single-crystal diamond with direct ion microbeam writing. Focused high-energy ( MeV) helium ions are employed to selectively convert diamond with... more
We report on the systematic characterization of conductive micro-channels fabricated in single-crystal diamond with direct ion microbeam writing. Focused high-energy ( MeV) helium ions are employed to selectively convert diamond with micrometric spatial accuracy to a stable graphitic phase upon thermal annealing, due to the induced structural damage occurring at the end-of-range. A variable-thickness mask allows the accurate modulation of the depth at which the microchannels are formed, from several μm deep up to the very surface of the sample. By means of cross-sectional transmission electron microscopy (TEM) we demonstrate that the technique allows the direct writing of amorphous (and graphitic, upon suitable thermal annealing) microstructures extending within the insulating diamond matrix in the three spatial directions, and in particular that buried channels embedded in a highly insulating matrix emerge and electrically connect to the sample surface at specific locations. Moreov...
Research Interests: Condensed Matter Physics, FTIR spectroscopy, Applied Physics, Evaporation, Doping, and 15 moreGrain Boundaries, Ellipsometry, Fabrication, Grain size, Grain Boundary, Diode, Electrical Conductivity, Electrical Properties, Ferroelectricity, Freeze Drying, Crystal Defects, Gallium Arsenide, Fermi Level, Experimental Data, and Electrical And Electronic Engineering
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It is possible to create full-sp3 amorphous nanostructures within the bulk crystal of diamond with room-temperature ion-beam irradiation, followed by an annealing process that does not involve the application of any external mechanical... more
It is possible to create full-sp3 amorphous nanostructures within the bulk crystal of diamond with room-temperature ion-beam irradiation, followed by an annealing process that does not involve the application of any external mechanical pressure.
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Color centres in diamond represent a very interesting system for realizing single photon emitters, even at room temperature, in particular are attracting an ever-growing interest in quantum optics, quantum information and quantum sensing,... more
Color centres in diamond represent a very interesting system for realizing single photon emitters, even at room temperature, in particular are attracting an ever-growing interest in quantum optics, quantum information and quantum sensing, due to their appealing photo-physical properties combined with ease of access and manipulation in a solid state system characterized by high transparency and structural stability. Literally hundreds of optically active color centers can be created and controlled in the diamond matrix, to be employed either as bright and stable single-photon sources or individual spin systems with optical readout, with record performances even at room temperature. In concurrence with the remarkable results obtained at the state of the art on the exploitation of the unique properties of the negatively-charged nitrogen-vacancy complex (NV), new and appealing color centers are continuously being discovered and characterized. In the present contribution, the most recent...
Properties of quantum light represent a tool for overcoming limits of classical optics. Several experiments have demonstrated this advantage ranging from quantum enhanced imaging to quantum illumination. In this work, experimental... more
Properties of quantum light represent a tool for overcoming limits of classical optics. Several experiments have demonstrated this advantage ranging from quantum enhanced imaging to quantum illumination. In this work, experimental demonstration of quantum-enhanced resolution in confocal fluorescence microscopy will be presented. This is achieved by exploiting the non-classical photon statistics of fluorescence emission of single nitrogen-vacancy (NV) color centers in diamond. By developing a general model of super-resolution based on the direct sampling of the kth-order autocorrelation function of the photoluminescence signal, we show the possibility to resolve, in principle, arbitrarily close emitting centers. Finally, possible applications of NV-based fluorescent nanodiamonds in biosensing and future developments will be presented.