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Hydrogenated amorphous silicon (a-Si:H) is a material having an intrinsically high radiation hardness that can be deposited on flexible substrates such as polyimide (PI). For these properties, a-Si:H can be used for the production of flexible sensors. a-Si:H sensors can be successfully utilized in dosimetry, beam monitoring for particle physics (X-ray, electron, gamma ray, and proton detection) and radiotherapy, radiation flux measurement for space applications (study of solar energetic particles and stellar events), and neutron flux measurements. In this article, we have studied the dosimetric X-ray response of n-i-p diodes deposited on PI. We measured the linearity of the photocurrent response to X-rays versus dose rate from which we have extracted the dosimetric X-ray sensitivity at various bias voltages. In particular, low bias voltage operation has been studied to assess the high energy efficiency of these kinds of sensors. A measurement of stability of X-ray response versus time has been shown. The effect of detectors annealing has been studied. Operation under bending at various bending radii is also shown.

Recent advancements in quantum technologies and advanced detection experiments have underscored the pressing need for the detection of exceedingly weak signals within the microwave frequency spectrum. Addressing this challenge, the Josephson Traveling Wave Parametric Amplifier (JTWPA) has been proposed as a cryogenic front-end amplifier capable of approaching the quantum noise limit while providing a relevant bandwidth. This research is centered on a comprehensive numerical investigation of the JTWPA, without resorting to simplifications regarding the nonlinearity of the essential components. Specifically, this study focuses on a thorough examination of the system, characterized by coupled nonlinear differential equations representing all components of the device. Proper input and output signals at the device's boundaries are considered. The analysis of the output signals undergoing the parametric amplification process involves a detailed exploration of phase-space dynamics and Fourier spectral analysis of the output voltage. This study is conducted while considering the parameters ruling the response of the device under pump and signal excitations. In addition to the expected signal amplification, the findings reveal that the nonlinear nature of the system can give rise to unforeseen phenomena, depending on the system's operational conditions, which include: the generation of pump tone harmonics, modulation of the signal gain, and incommensurate frequency generation—effects that are not easily accommodated by simplistic linearized approaches.

In the frame of the Next Generation Europe program, the EU program to boost after-COVID recovery, the Italian Minister of University and Research has funded a project called Innovative Research Infrastructure for applied Superconductivity (IRIS). New laboratories will be built or upgraded in six poles: Milan (hub of the infrastructure), Genoa, Frascati, Naples, Salerno, and Lecce, to carry out basic research on magnetism and superconducting materials, test of wires, tapes, and large current cables, superconducting magnets construction with advanced instrumentation, power tests of magnets, and a special facility for high current-high voltage superconducting lines. The program will be executed over three years and then will operate for at least 10 years. It includes two first demonstrators: one HTS magnet to be operated at 10–20 K and a superconducting line of 1 GW (40 kA–25 kV) about 140 m long. The demonstrators anticipate the main scope of the investment in the IRIS infrastructure: to support the use of superconductivity for improving sustainability by decreasing the energy consumption without compromising performance. This article describes the global IRIS project.

The growing interest in quantum technologies, from fundamental physics experiments to quantum computing, demands for extremely performing electronics only adding the minimum amount of noise admitted by quantum mechanics to the input signal (i.e., quantum-limited electronics). Superconducting microwave amplifiers, due to their dissipationless nature, exhibit outstanding performances in terms of noise (quantum limited), and gain. However, bandwidth and saturation power still show space for substantial improvement. Within the DARTWARS11DARTWARS (Detector Array Readout with Traveling Wave AmplifieRS), funded by Italian National Nuclear Institute (INFN), is a quantum technologies project targeted at the development of wideband superconducting amplifiers with noise at the quantum limit and the implementation of a quantum-limited readout in different types of superconducting detectors and qubit. collaboration, we are developing state-of-the-art microwave superconducting amplifiers based on Josephson junction arrays and on distributed kinetic inductance transmission lines. Here we report the realization of a setup for the characterization of the performances of Josephson traveling-wave parametric amplifiers at a temperature of 300 mK. Although in the final experimental setup, these amplifiers will operate at a base temperature of about 20 mK, their characterization at 300 mK allows to evidence the main aspects of their performances, but the ultimate noise level. This represents a quick and relatively inexpensive way to test these superconductive devices that can be of help to improve their design and fabrication.

The recent developments in quantum technologies, as well as advanced detection experiments, have raised the need to detect extremely weak signals in the microwave frequency spectrum. To this aim, the Josephson travelling wave parametric amplifier, a device capable of reaching the quantum noise limit while providing a wide bandwidth, has been proposed as a suitable cryogenic front-end amplifier. This work deals with the numerical study of a Josephson travelling wave parametric amplifier, without approximations regarding the nonlinearity of the key elements. In particular, we focus on the investigation of the system of coupled nonlinear differential equations representing all the cells of the Josephson travelling wave parametric amplifier, with proper input and output signals at the boundaries. The investigation of the output signals generated by the parametric amplification process explores the phase-space and the Fourier spectral analysis of the output voltage, as a function of the parameters describing the pump and signal tones that excite the device. Beside the expected behavior, i.e., the signal amplification, we show that, depending on the system operation, unwanted effects (such as pump tone harmonics, incommensurate frequency generation, and noise rise), which are not accounted for in simple linearized approaches, can be generated in the whole nonlinear system.

Nanocrystals (NCs) of transparent conducting oxides with a localized surface plasmon resonance (LSPR) in the near-infrared (NIR) spectral region show promising electrochromic properties for the development of a new generation of dynamic “smart windows”. In this regard, we exploit thin films of F, In-codoped CdO (FICO) NCs as active coatings for electrochromic devices. The control over the dopants concentration in FICO NCs results in fine tuning of their LSPR across the NIR region of the electromagnetic spectrum. Highly transparent mesoporous electrodes were prepared from colloidal FICO NCs by in situ ligand exchange of the pristine organic capping ligands. This approach preserves the optical and electrical properties of native NCs and delivers highly homogeneous, nonscattering films with a good electronic coupling between the NCs. We achieved a dynamic control over the LSPR frequency by reversible electrochemical doping, hence a spectrally selective modulation of the optical transmittance in the NIR region of the solar spectrum, which carries nearly 50% of the whole solar heat. Spectroelectrochemical characterization, coloration efficiency, and switching kinetics results indicate that thin film based on FICO NCs are potential candidates for plasmonic electrochromic applications. Moreover, the high electron mobility and wide optical bandgap of FICO makes NCs of this material suitable for large-area devices capable of dynamically controlling the heat load coming from the solar infrared radiation, without affecting the visible light transmittance.

The structural, dielectric, and ferroelectric characterization of multiphase Bi‐Fe‐O prepared with an excess of Bi up to 20% is reported. It is found that the dominant phase in all samples is the BiFeO3perovskite in addition to an increasing amount of the Bi‐rich sillenite phases (Bi12.5Fe0.5O19.48/Bi25FeO39) with the Bi excess content. At room temperature, the multiphase Bi‐Fe‐O results in advanced electrical properties, with higher dielectric constant (161 at 1 MHz) and low losses (tanδ = 0.032 at 1 MHz). The ferroelectric character of multiphase ceramics is confirmed by PUND measurements, which shows increased polarization values and coercive field with respect to the single phase ceramics. Multiphase Bi‐Fe‐O ceramicsprepared with Bi excess (up to 20%) are morphologically, structurally, dielectrically, and ferroelectrically investigated. Improved dielectric and ferroelectric properties are observed in the multiphase samples with respect to the single phase bismuth ferrite and further insight on the effect of microstructure on the ceramics dielectric properties is achieved.