A Molecule‐Based Single‐Photon Source Applied in Quantum Radiometry

Single photon sources (SPSs) based on quantum emitters hold promise in quantum radiometry as metrology standard for photon fluxes at the low light level. Ideally this requires control over the photon flux in a wide dynamic range, sub-Poissonian photon statistics and narrow-band emission spectrum. In this work, a monochromatic single-photon source based on an organic dye molecule is presented, whose photon flux is traceably measured to be adjustable between 144 000 and 1320 000 photons per second at a wavelength of (785.6 +/- 0.1) nm, corresponding to an optical radiant flux between 36.5 fW and 334 fW. The high purity of the single-photon stream is verified, with a second-order autocorrelation function at zero time delay below 0.1 throughout the whole range. Featuring an appropriate combination of emission properties, the molecular SPS shows here application in the calibration of a silicon Single-Photon Avalanche Detector (SPAD) against a low-noise analog silicon photodiode traceable to the primary standard for optical radiant flux (i.e. the cryogenic radiometer). Due to the narrow bandwidth of the source, corrections to the SPAD detection efficiency arising from the spectral power distribution are negligible. With this major advantage, the developed device may finally realize a low-photon-flux standard source for quantum radiometry

Chitosan-Capped Au Nanoparticles for Laser Photothermal Ablation Therapy: UV-Vis Characterization and Optothermal Performances

We have reported on the synthesis and characterization of near-infrared- (NIR-) absorbing colloidal nanoparticles prepared by exploiting the one-step reaction of HAuCl4 and Na2S2O3, followed by their stabilization with chitosan. This reaction also produces a big amount of unwanted nanoparticles detuned with respect to the NIR spectral region. For this reason, it is usually assumed that the product has to be filtered and enriched to enhance its NIR absorption, and the possible exploitation of the simpler raw product has never been worthy to be considered. Aiming to investigate this missing aspect, we chose to avoid the purification steps and rather focused on the preparation of the unrefined colloid, identifying the synthesis conditions that maximize its NIR absorbance and, subsequently, testing it as an optothermal transducer by measuring its molar heating rate (MHR). As expected, we found that the performances of the raw colloid are indeed lower than those of its refined version, but only to a limited extent. Moreover, MHR is unexpectedly higher than that deducible for other classical NIR-absorbing nanoparticles, like Au nanorods or Au nanostars. Thus, the product of the simpler preparation protocol appears as a competitive trade-off solution between easy manufacturing and optothermal performances

All optical switches based on the coupling of surface plasmon polaritons

We studied the potentials of All Optical Switches (AOS) based on the intensity-dependent coupling and decoupling of light into the SPP modes (Surface Plasmon Polaritons) of a sinusoidally corrugated thin metal film (TMF), due to Kerr induced refractive index changes of the surrounding dielectrics. The ideal device has two spatially separated outputs, collecting the reflected and transmitted light and the active volume can be as small as 10(-2) mm(3). Gold and PTS (poly-(2,4-hexadiyne-1,6-diol bis(p-toluene sulfonate) are the materials considered. Losses are limited to 1.5 dB,while a 20 dB extinction ratio per gate has been theoretically demonstrated with signal pulsewidths of 5-10 ps , using a maximum optical switching peak power of 11 kW

Single photon sources for quantum radiometry: a brief review about the current state-of-the-art

Single-photon sources have a variety of applications. One of these is quantum radiometry, which is reported on in this paper in the form of an overview, specifically of the current state of the art in the application of deterministic single photon sources to the calibration of single photon detectors. To optimize single-photon sources for this purpose, extensive research is currently carried out at the European National Metrology Institutes (NMIs), in collaboration with partners from universities. Single-photon sources of different types are currently under investigation, including sources based on defect centres in (nano-)diamonds, on molecules and on semiconductor quantum dots. We will present, summarise, and compare the current results obtained at European NMIs for single-photon sources in terms of photon flux, single-photon purity, and spectral power distribution as well as the results of single-photon detector calibrations carried out with this type of light sources.DFG, 390837967, EXC 2123: QuantumFrontiers - Licht und Materie an der Quantengrenz

Il Futuro della Cybersecurity in Italia: Ambiti Progettuali Strategici

Il presente volume nasce come continuazione del precedente, con l’obiettivo di delineare un insieme di ambiti progettuali e di azioni che la comunità nazionale della ricerca ritiene essenziali a complemento e a supporto di quelli previsti nel DPCM Gentiloni in materia di sicurezza cibernetica, pubblicato nel febbraio del 2017. La lettura non richiede particolari conoscenze tecniche; il testo è fruibile da chiunque utilizzi strumenti informatici o navighi in rete. Nel volume vengono considerati molteplici aspetti della cybersecurity, che vanno dalla definizione di infrastrutture e centri necessari a organizzare la difesa alle azioni e alle tecnologie da sviluppare per essere protetti al meglio, dall’individuazione delle principali tecnologie da difendere alla proposta di un insieme di azioni orizzontali per la formazione, la sensibilizzazione e la gestione dei rischi. Gli ambiti progettuali e le azioni, che noi speriamo possano svilupparsi nei prossimi anni in Italia, sono poi accompagnate da una serie di raccomandazioni agli organi preposti per affrontare al meglio, e da Paese consapevole, la sfida della trasformazione digitale. Le raccomandazioni non intendono essere esaustive, ma vanno a toccare dei punti che riteniamo essenziali per una corretta implementazione di una politica di sicurezza cibernetica a livello nazionale. Politica che, per sua natura, dovrà necessariamente essere dinamica e in continua evoluzione in base ai cambiamenti tecnologici, normativi, sociali e geopolitici. All’interno del volume, sono riportati dei riquadri con sfondo violetto o grigio; i primi sono usati nel capitolo introduttivo e nelle conclusioni per mettere in evidenza alcuni concetti ritenuti importanti, i secondi sono usati negli altri capitoli per spiegare il significato di alcuni termini tecnici comunemente utilizzati dagli addetti ai lavori. In conclusione, ringraziamo tutti i colleghi che hanno contribuito a questo volume: un gruppo di oltre 120 ricercatori, provenienti da circa 40 tra Enti di Ricerca e Università, unico per numerosità ed eccellenza, che rappresenta il meglio della ricerca in Italia nel settore della cybersecurity. Un grazie speciale va a Gabriella Caramagno e ad Angela Miola che hanno contribuito a tutte le fasi di produzione del libro. Tra i ringraziamenti ci fa piacere aggiungere il supporto ottenuto dai partecipanti al progetto FILIERASICURA