We develop a fully complementary metal-oxide semiconductor (CMOS) fabrication technique for the realization of a superconducting qubit network (SQN). In our current research work, we focus on a single-angle overlap Josephson junction fabrication technique, based on the lift-off process for defining both base and top electrodes, avoiding the wiring insulator layer and requiring an RF Ar etching process before AlOx barrier growth. The fabricated Al/AlOx/Al microscale Josephson junctions have been tested at low temperature (T = 300 mK) in the superconducting state using current-voltage characteristic measurements.

Reduced graphene oxide (rGO) has attracted interest as a potential, cost-effective alternative to graphene layers produced by single-crystal thin-film growth techniques. Its solubility in various solvents, the ability to tune its optical and electrical properties, the ability to manipulate the optoelectronic properties of rGO-based heterojunctions, and the possibility of depositing it on flexible substrates broaden its potential applications, from electro-optical communications to environmental monitoring. In this work, we present a characterization of reduced graphene oxide (rGO) deposited on p-type Si3N4/Si substrate using different techniques such as Raman spectroscopy, optical transmittance, and current-voltage measurements under dark and illuminated conditions in the 400-700 nm range. Furthermore, the temperature dependence of the photocurrent of the rGO-based photoconductive device was studied in the temperature range from 300 K to 77 K. It has been shown that the electron transport mechanism through the p-type rGO/SiN/Si heterojunction at low voltage involves mainly a hopping process at 77 K and a thermionic mechanism at room temperature. Furthermore, the Fowler-Nordheim tunneling and trap-limiting mechanisms allow the presence of charge carriers in the device at both temperatures. Estimation of the main figures of merit, responsivity, detectivity, and NEP, shows an improvement in photodetection performance at low temperatures.

Superconducting qubit networks (SQNs) embedded in a low-dissipative resonator is a promising device allowing one not only to establish the collective quantum dynamics on a macroscopic scale but also to greatly enhance the sensitivity of detectors of microwave photons. A quantum ac Stark effect provided by coupling between an SQN and microwave photons of a resonator, leads to a strong nonlinear interaction between photons. Here, we present a two-tone spectroscopy experiment in which a set of 10 superconducting flux qubits is coupled to the input R- resonator and the output T- transmission line. An external microwave pump field close to the resonance frequency populates macroscopically the resonator mode as a Bose-Einstein condensate, while a second probe beam scans the resonances referred also as Bogoliubov-like excitations. The corresponding excitation frequency measured from the transmission coefficient, |S21(f)| displays an abrupt change of the resonant dip position once the power of the pump field overcomes a critical value Pcr. This sharp shift occurs in a narrow region of pump frequencies, and can be tuned by an applied magnetic field. It is a signature of bistability of the photon number inside the resonator, in agreement with theory.

The seminal phenomenon of the Bose-Einstein condensation has been observed on a large variety of physical platforms, e.g., superfluid helium, fermions with attractive interactions, quasiparticles in solids, and ultracold atomic gases. Recently, the Bose–Einstein condensation of non-interacting photons in an optical microcavity has been confirmed experimentally. Here, we report the experimental observation of Bose-Einstein like condensation and collective Bogoliubov excitations in a low dissipative microwave resonator with embedded superconducting quantum network composed of multiple flux qubits. Under strong coherent pumping the resonator mode becomes macroscopically populated, giving rise to hybridized photon–qubit collective modes. The Bogoliubov-like collective excitations appearing in a response to a nearby-frequency probe tone, accompanied by pronounced bistability and hysteresis in the measured transmission coefficient, provide the first experimental evidence of a Bose–Einstein–like condensate of microwave photons on a superconducting circuit platform. A theoretical framework based on Gross-Pitaevskii formalism and taking into account the ac Stark effect inducing the effective interaction between photons, quantitatively reproduces the experimental observations and identifies the regime of appearance of microwave Bogoliubov excitations. These results establish a proof of principle for exploiting driven collective states in superconducting circuits as a platform for quantum-limited microwave detection and engineered many-body photonic systems for quantum information processing.

In this work we report on a two-tone spectroscopy experiment performed on a superconducting qubit network (SQN) composed of ten flux qubits coupled to low-dissipative microwave resonators. Non-linear effects such as the shift of the absorption peak both by power and by frequency of the pump second tone signal were observed, due to the multiphoton interaction between pump microwave signal and the SQN. We experimentally demonstrated that SQN detector with collective quantum state permits to detect low power microwave signals with a frequency of 7.748 GHz in the range between –110 and –75 dBm, which is lower than the microwave power range of conventional Schottky detector.

Photodetectors are of great interest in several technological applications thanks to their capability to convert an optical signal into an electrical one through light–matter interactions. In particular, broadband photodetectors based on graphene/silicon heterojunctions could be useful in multiple applications due to their compelling performances. Here, we present a 2D photodiode heterojunction based on a graphene single layer deposited on p-type and n-type Silicon substrates. We report on the electro-optical properties of the device that have been measured in dark and light conditions in a spectral range from 400 nm to 800 nm. The comparison of the device’s performance in terms of responsivity and rectification ratio is presented. Raman spectroscopy provides information on the graphene single layer’s quality and oxidation. The results showcase the importance of the doping of the silicon substrate to realize an efficient heterojunction that improves the photoresponse, reducing the dark current.

Photodetectors are of great interest in several technological applications thanks to their capability to convert an optical signal into an electrical one through light-matter interactions. In particular, broadband photodetectors are used in multiple applications such as environmental monitoring, imaging, fire detection, and astronomical observations. We present a two-dimensional photodiode heterojunction based on reduced graphene oxide (rGO) deposited on an n-type Silicon substrate. We report on the electro-optical properties of the device that have been measured in dark and light conditions into a spectral range from UV to IR. The room temperature current–voltage (I–V) measurements of rGO/n-Si photodetector exhibits a reverse saturation current linearly dependent on the light power. The main figures of merit of the photodetector such as linearity and responsivity have been evaluated and compared with the recent progress obtained substituting the rGO with a graphene single layer (Gr) on the similar n-Si substrate. The photoconductive properties and analysis of the two devices are presented and discussed. Finally, the experimental results demonstrate the feasibility of the rGO/n-Si and Gr/n-Si device to detect light from UV to IR light, nominating graphene-based heterojunction as a novel candidate for the realization of new broadband photodetectors.

Axions detection requires the ultimate sensitivity down to the single-photon limit. In the microwave region, this corresponds to energies in the yJ range. This extreme sensitivity has to be combined with an extremely low dark-count rate since the probability of axions conversion into microwave photons is supposed to be very low. To face this complicated task, we followed two promising approaches that both rely on the use of superconducting devices based on the Josephson effect. The first one is to use a single Josephson junction (JJ) as a switching detector (i.e., exploiting the superconducting to normal state transition in the presence of microwave photons). We designed a device composed of a coplanar waveguide terminated on a current-biased JJ. We tested its efficiency to pulsed (pulse duration 10 ns) microwave signals since this configuration is closer to an actual axions search experiment. We show how our device is able to reach detection capability of the order of ten photons with the frequency of 8 GHz. The second approach is based on an intrinsically quantum device formed by two resonators coupled only via a superconducting qubit network. This approach relies on quantum nondemolition measurements of the resonator photons. We show that by injecting radiofrequency power into the resonator, the frequency position of the resonant drop in the transmission coefficient (S21) can be modulated up to 4 MHz. We anticipate that, once optimized, both the devices have the potential to reach single-photon sensitivity.

In recent years, Silicon Photomultipliers (SiPMs) have proven to be highly suitable devices for applications where high sensitivity to low-intensity light and fast responses are required. Among their many advantages are their low operational voltage when compared with classical photomultiplier tubes, mechanical robustness, and increased photon detection efficiency (PDE). Here we present a full characterization of a SiPM device technology developed in Italy by Fondazione Bruno Kessler, which is suitable for Cherenkov light detection in the Near-Ultraviolet (NUV) band. This device is a High-Density (HD) NUV SiPM, based on a microcell of 40 mu m x 40 mu m and with an area of 6 x 6 mm2, providing low levels of dark noise and high PDE peaking in the NUV band. This particular device has been selected to equip a part of the focal plane of the Schwarzschild-Couder Telescope (SCT) prototype proposed for the Cherenkov Telescope Array (CTA) Observatory.

Experimental search of galactic axions requires detection of single photons in the microwave range. We work on a novel approach to detect single microwave photons based on a coherent collective response of quantum states occurring in a superconducting qubit network (SQN) embedded in a low-dissipative superconducting resonator. We propose a two resonators detector configuration with two parallel resonators without common part and with separated input and output terminals. The device consists of a low-dissipative resonator with embedded SQN in which microwave photons arrive ("signal resonator"), and a transmission line for measuring the frequency dependent transmission coefficient demonstrating resonant drops at the qubit frequencies ("readout resonator"). In comparison with T-type three terminal device recently proposed and investigated by us, the device with two resonators with separated input and output terminals doesn't contain common part of both resonators and exclude an unwanted noise from measurement readout circuits to the signal resonator. A layout of two resonators four terminal SQN detectors containing 5 flux qubits weakly coupled to a low-dissipative signal and readout resonator was developed and optimized. The samples were fabricated by Manhattan Al-based technology with Nb resonator circuits. The SQN detector was experimentally tested in terms of microwave measurements of scattering parameters of both resonators and crosstalk properties. Comparison of experimental data with results of the simulations permits one to conclude that the electromagnetic conditions of the fundamental resonant peak of 8.5 GHz of both resonators aren't affected by the crosstalk phenomenon and their performances provided by the design remain not altered for correct device operation.

Nowadays, due to the competitive economic scenario, industries ever more need to focus on manufacturing speed, increasing efficiency and steady quality. More industrial sectors see additive manufacturing (AM) as a possible way to enhance their processes and increase production efficiency. Thanks to its versatility the Fused Deposition Modelling (FDM), also known as Fused Filament Fabrication (FFF) technique, is one the most attractive processes in Industry 4.0 paradigm. This technique, thanks to its low-cost, is spreading widely in industrial sectors, from biomedical to aerospace to cite some. In this frame a valid solution is to use composite materials Among many, particular attention is paid to thermoplastic systems based on polyether-ether-ketone (PEEK) reinforced with short carbon fibre (CF). The PEEK is a high-performance semi-crystalline thermoplastic polymer that belongs to the polyaryl-ether-ketone family (PAEK). 3D printing, being a novel technology, it must be validated by understanding the behaviours of components and structures. At this purpose, we used different optical techniques for analysing advanced short fibre composites realized by 3D printing. Different CFR-PEEK samples with short carbon fibre at 10% by weight were realized by the FFF technique and characterized in terms of failure mode and mechanical behaviour. Optical tools have been used to retrieve full-field data and expand information about the mechanical behaviour of the investigated material, i.e. 2D Digital Image Correlation (2D-DIC) and Electronic Speckle Pattern Interferometry (ESPI), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM).

The scope of cyber security becomes wider and wider with time and cyber threats rapidly change. This strongly impacts the performance of companies whose success heavily depends on the health of the underlying network infrastructure. The ability to have a clear understanding of the security exposure of a network in its entirety hence becomes part of the mission of such companies. In this work we present the design and implementation of a distributed measurement solution to assess the cyber security exposure of an ICT Infrastructure. We provide means to define cyber security indicators through an automated and repeatable measurement process. We prove the efficiency of the presented methodology by testing it on real-world infrastructure facilities, discussing the results obtained in two different scenarios: a comparison of networks with different characteristics and a real-time monitoring of the defined metrics.

Heterojunction photodetector based on reduced graphene oxide (rGO) has been realized using a spin coating technique. The electrical and optical characterization of bare GO and thermally reduced GO thin films deposited on glass substrate has been carried out. Ultraviolet–visible–infrared transmittance measurements of the GO and rGO thin films revealed broad absorption range, while the absorbance analysis evaluates rGO band gap of about 2.8 eV. The effect of GO reduction process on the photoresponse capability is reported. The current–voltage characteristics and the responsivity of rGO/n-Si based device have been investigated using laser diode wavelengths from UV up to IR spectral range. An energy band diagram of the heterojunction has been proposed to explain the current versus voltage characteristics. The device demonstrates a photoresponse at a broad spectral range with a maximum responsivity and detectivity of 0.20 A/W and 7 × 10 10 cmHz/W, respectively. Notably, the obtained results indicate that the rGO based device can be useful for broadband radiation detection compatible with silicon device technology.

We present a framework able to combine exposure indicators and predictive analytics using AI-tools and big data architectures for threats detection inside a real industrial IoT sensors network. The described framework, able to fill the gaps between these two worlds, provides mechanisms to internally assess and evaluate products, services and share results without disclosing any sensitive and private information. We analyze the actual state of the art and a possible future research on top of a real case scenario implemented into a technological platform being developed under the H2020 ECHO project, for sharing and evaluating cybersecurity relevant informations, increasing trust and transparency among different stakeholders.

The critical current value is a key parameter of a Superconducting Quantum Interference Device. In this paper we investigate the effects of different critical current values on the noise performance of SQUID magnetometers. By using a statistical-like approach, we measure the spectral density of magnetic field noise of 200 magnetometers relating the values to the critical current change. The magnetometer consists of a dc-SQUID in a washer shape magnetically coupled to a square superconducting pickup coil. The fully integrated design includes a feedback coil to work in Flux Locked Loop mode and an Additional Positive Feedback circuit to increase its voltage responsivity. The main application field of these sensors is the magnetoencephalography that exploits multichannel systems based on SQUID magnetometers, in which the uniformity of noise performance of the sensors is needed. We found that a best value of critical current is 20 μΑ and also that a value spread ranging from 8 to 40 μm, does not affect in an evident way the sensitivity of such magnetometers. The corresponding noise spectral density remains within the range 2 – 6 fT/⎷Hz.

In the present article, we present the experimental results concerning the fine-tuning and optimization of superconducting quantum interference device (SQUID) parameters by thermal annealing. This treatment allows for the modification of the parameters in order to meet a specific application or to adjust the device parameters to prevent the increase of magnetic field noise and work instability conditions due to a different critical current with respect to the design value. In particular, we report the sensor critical current, the voltage–flux (V–Φ) characteristics and the spectral density of the magnetic field of SQUID magnetometers for different annealing temperatures. The measurements demonstrate that it is possible to achieve a fine control of the most important device parameters. In particular, we show that thermal annealing allows for the reduction of SQUID noise by more than a factor of 5 and makes the device working operations very stable. These results are very useful in view of quantum technology applications related to superconducting quantum computing where the correct functioning of the quantum bit depends on the fine control of the superconducting quantum device parameters and selectable annealing is possible by using a suitable laser as a thermal source.

In a previous work, we have presented an innovative theoretical model to describe the evolution of the life cycle of a new technology. We have proposed a mathematical approach based on a rate equation, similar to that used to describe quantum level transitions. The model is able to describe the hype curve evolution in many relevant conditions, which can be associated with various external parameters. In this article, we apply this model to describe the evolution of the number of publications in some different research fields that are very current and extremely advanced in terms of social impact. The applications have been chosen in the fields of biomolecular chemistry, genetics and superconducting nanoelectronics.

The magneto-mechanical behaviour of structural steel specimens stressed up to the plastic deformation stage was investigated using a 2nd order gradiometer based on Giant Magneto Resistive (GMR) sensors. The correlation between the gradient of the magnetization and the dislocation density before the crack initiation inside the test material was reported. The capability of the GMR scanning sensor to detect the residual magnetization due to the tensile stress with a non-invasive technique was demonstrated.

Nowadays the use of advanced composite materials in aeronautics, both civil and military, in automotive and in sport applications, citing some, is well established. The characteristics of composite materials in terms of weight, fatigue resistance and corrosion resistance make them competitive with respect to conventional ones. On the other side, the fabrication process of the most employed composites reinforced by carbon fibers or glass fibers, needs of complex steps that not always are environmental complaisant. Moreover, such fibers are not themselves "green". For these reasons, in the last decades, the use of natural reinforcing fibers has gained an increasing attention allowing the development of new materials with the same advantages of composite systems but respecting the environment. Furthermore, such materials for their structural complexity are not always compatible with the use of standard non-destructive evaluation as the ultrasounds methods. In this work the efficiency of the employment of optical interferometric techniques as non-destructive evaluation methods in full field modality is proved on novel "green" composite materials. In particular, Electronic Speckle Pattern Interferometry has been tested on different kinds of specimens after flexural tests.

Micro- and nano-sized superconducting quantum interference devices (SQUIDs) allow the measurements of extremely low magnetic moment. In the last decade, many efforts have been devoted to the study and the development of these quantum sensors at a nanometric scale (nanoSQUIDs). In this paper, a study of performance of these nanosensors in different configurations is presented. In particular, the magnetic flux coupling and the spin sensitivity have been computed for planar nanoSQUIDs in square and rectangular shapes in the presence of an elementary magnetic moment (Bohr magneton). The computation has been carried out as a function of the position of the Bohr magneton within the sensitive SQUID loop and for different distances from the loop plane. The same characteristics have also been computed for a square nanoSQUID as a function of side length taking into account the increase of the magnetic flux noise as a function of the loop inductance. In addition, a configuration including a nonflat geometry has been analyzed.