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Efficiency Optimization of Ge‐V Quantum Emitters in Single‐Crystal Diamond upon Ion Implantation and HPHT Annealing
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Photon Statistics Modal Reconstruction by Detected and Undetected Light
Get PDFA novel technique is introduced for the reconstruction of multimode optical fields, based on simultaneously exploiting both the generalized Glauber's K-th-order correlation function g(K)g<^>{(K)} and a recently proposed anti-correlation function (dubbed theta(K)\theta <^>{(K)}) which is resilient to Poissonian noise. It is experimentally demonstrated that this method yields mode reconstructions with higher fidelity with respect to those obtained with reconstruction methods based only on g(K)g<^>{(K)}'s, even requiring less "a priori" information. The reliability and versatility of this technique make it suitable for a widespread use in real applications of optical quantum measurement, from quantum information to quantum metrology, especially when one needs to characterize ensembles of single-photon emitters in the presence of background noise (due, for example, to residual excitation laser, stray light or unwanted fluorescence)
Permselectivity and Ionic Conductivity Study of Na+ and Br− Ions in Graphene Oxide-Based Membranes for Redox Flow Batteries
Get PDFPermselectivity of a membrane is central for the development of electrochemical energy storage devices with two redox couples, such as redox flow batteries (RFBs). In RFBs, Br3−/Br− couple is often used as a catholyte which can cross over to the anolyte, limiting the battery’s lifetime. Naturally, the development of permselective membranes is essential to the success of RFBs since state-of-the-art perfluorosulfonic acid (PFSA) is too costly. This study investigates membranes of graphene oxide (GO), polyvinylpyrrolidone (PVP), and imidazole (Im) as binder and linker, respectively. The GO membranes are compared to a standard PFSA membrane in terms of ionic conductivity (Na+) and permselectivity (exclusion of Br−). The ionic conduction is evaluated from electrochemical impedance spectroscopy and the permselectivity from two-compartment diffusion cells in a four-electrode system. Our findings suggest that the GO membranes reach conductivity and permselectivity comparable with standard PFSA membranes
Droplet orthogonal impact on nonuniform wettability surfaces
Get PDFThe vast majority of prior studies on droplet impact have focused on collisions of liquid droplets with spatially homogeneous (i.e., uniform-wettability) surfaces. But in recent years, there has been growing interest on droplet impact on nonuniform wettability surfaces, which are more relevant in practice. This paper presents first an experimental study of axisymmetric droplet impact on wettability-patterned surfaces. The experiments feature millimeter-sized water droplets impacting centrally with (Figure presented.) on a flat surface that has a circular region of wettability (Figure presented.) (Area 1) surrounded by a region of wettability (Figure presented.) (Area 2), where (Figure presented.) (i.e., outer domain is less wettable than the inner one). Depending upon the droplet momentum at impact, the experiments reveal the existence of three possible regimes of axisymmetric spreading, namely (I) interior (only within Area 1) spreading, (II) contact-line entrapment at the periphery of Area 1, and (III) exterior (extending into Area 2) spreading. We present an analysis based on energetic principles for (Figure presented.), and further extend it for cases where (Figure presented.) (i.e., the outer domain is more wettable than the inner one). The experimental observations are consistent with the scaling and predictions of the analytical model, thus outlining a strategy for predicting droplet impact behavior for more complex wettability patterns
Optical limiter based on PT-symmetry breaking of reflectionless modes
Get PDFThe application of parity-time (PT) symmetry in optics, especially PT-symmetry breaking, has attracted considerable attention as an approach to controlling light propagation. Here, we report optical limiting by two coupled optical cavities with a PT-symmetric spectrum of reflectionless modes. The optical limiting is related to broken PT symmetry due to light-induced changes in one of the cavities. Our experimental implementation involves a three-mirror resonator of alternating layers of ZnS and cryolite with a PT-symmetric spectral degeneracy of two reflectionless modes. The passive optical limiting is demonstrated by measurements of single 532 nm 6 ns laser pulses and thermo-optical simulations. At fluences below 10 mJ=cm2, the multilayer exhibits a flattop passband at 532 nm. At higher fluences, laser heating combined with the thermo-optic effect in ZnS leads to cavity detuning and PT-symmetry breaking of the reflectionless modes. As a result, the entire multilayer structure quickly becomes highly reflective, protecting itself from laser-induced damage. The cavity detuning mechanism can differ at much higher limiting thresholds and include nonlinearity
Fundamentals of Measurement: Giovanni Giorgi and the International System of Units
Get PDFElectrical engineers and technicians face today many professional challenges, but the problem of the choice of the measurement units and their conversion is not one of those. Our colleagues working in mechanics or thermal engineering have to deal with inches and metres, gallons and litres, calories, BTUs and joules. In electricity, everything is smoother: the voltage is always measured in volt, the resistance in ohm; one volt times one ohm gives one watt, and so on. No ambiguities occur, no calculations with weird conversion factors are needed
Anharmonic Assignment of the Water Octamer Spectrum in the OH Stretch Region
Get PDFWe interface thequasi-classical trajectory approachwith an ab initio potential energy surface for waterto assign thevibrational spectroscopical features of the OH stretch region of thewater octamer cluster, which is considered to be a precursor of ice.An attempt by Li et al. to assign their recent reference experimentinvolved lower-level calculations based on an ad hoc scaled harmonic approach. Differently from the conclusions of thisprevious assignment, which invoked the contribution of 5 conformersand a solvated form of the water heptamer in the spectrum, we findout that the spectroscopic features can be related to the 4 conformersof the octamer lying lower in energy
Riunione della ISO/TC213 Dimensional and Geometrical Product Specification and Verification
Get PDFLe attività dell’ISO hanno superato l’emergenza pandemica e l’obbligo di riunioni telematiche e sono tornate alle consuete riunioni in presenza. Se da un lato le riunioni telematiche hanno ridotto i rapporti personali diretti, spesso costruiti nelle pause caffè o a cena, dall’altro hanno dato impulso alla partecipazione di molti che non potevano permettersi di viaggiare per il mondo.
La riunione della ISO/TC 213 è stata in presenza nella sede del BSI (British Standards Institution, l’ente normatore britannico, detentore della segreteria dello ISO/TC 213) ma con collegamento telematico, ciò che ha reso ibrida la riunione. Tuttavia, il problema dei fusi orari non è risolvibile, e il programma non poteva che privilegiare o la riunione in presenza con orari pieni (9:00 18:00 locali) o quella remota con orari di compromesso fra le diverse regioni del mondo (12:00 15:00 UTC). Si è privilegiata la riunione in presenza, lasciando a carico dei collegati in remoto la lunghezza del collegamento e il fuso orario.
Si prevede che questo schema proseguirà in futuro