Archivio della ricerca - Fondazione Bruno Kessler
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Cognizant and Socially Aware Robotics
No full textBased on current developments in soft electronics, artificial intelligence, energy storage and harvesting strategies, and manufacturing technologies, this article presents how advances in several fields can unite to create an intelligent robotic system and predicts how close we are to the cognizant, socially aware robot
Conjugated polymer nanoparticles boosting growth and photosynthesis in biohybrid plants
No full text: Engineered nanomaterials integrated into photosynthetic systems could pave the way to new, exciting avenues towards biohybrid systems and renewable energy sources. Here, a biohybrid plant developed through the integration of poly(3-hexylthiophene) nanoparticles (P3HT-NPs) in Arabidopsis thaliana plants is presented. P3HT-NPs were used to enhance plant solar radiation absorption, with a spectrophotometric profile matching chlorophyll absorbance. The P3HT-NP-engineered biohybrid plants showed a 45% increase in root length, corresponding to a relevant enhancement in biomass production of up to 17% compared to the control group. The presented biohybrid plant might open a new route for improving CO2 capture and oxygen production, underscoring the transformative potential of combining nanomaterials with plant biology, and paving the way for novel biohybrid nano-engineered renewable energy sources
Critical mobility in policy making for epidemic containment
No full textWhen considering airborne epidemic spreading in social systems, a natural connection arises between mobility and epidemic contacts. As individuals travel, possibilities to encounter new people either at the final destination or during the transportation process appear. Such contacts can lead to new contagion events. In fact, mobility has been a crucial target for early non-pharmaceutical containment measures against the recent COVID-19 pandemic, with a degree of intensity ranging from public transportation line closures to regional, city or even home confinements. Nonetheless, quantitative knowledge on the relationship between mobility-contagions and, consequently, on the efficiency of containment measures remains elusive. Here we introduce an agent-based model with a simple interaction between mobility and contacts. Despite its simplicity, our model shows the emergence of a critical mobility level, inducing major outbreaks when surpassed. We explore the interplay between mobility restrictions and the infection in recent intervention policies seen across many countries, and how interventions in the form of closures triggered by incidence rates can guide the epidemic into an oscillatory regime with recurrent waves. We consider how the different interventions impact societal well-being, the economy and the population. Finally, we propose a mitigation framework based on the critical nature of mobility in an epidemic, able to suppress incidence and oscillations at will, preventing extreme incidence peaks with potential to saturate health care resources
Theoretical framework to design and optimize feasible all optical modulator based on multi passband slit array filters in frequency domain
No full textSingle-phase κ-Ga2O3 films deposited by metal-organic chemical vapor deposition on GaAs and ternary BxGa(1-x)As templates
No full textFor the first time, single-phase κ-Ga2O3 films were grown on (001) p-type GaAs and BxGa(1-x)As /GaAs templates using Metal-Organic Chemical Vapor Deposition (MOCVD). The films were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). TEM investigations revealed a thin polycrystalline nucleation layer followed by well-oriented columnar growth of the κ-phase in the Ga2O3/GaAs sample, while segregation and diffusion effects in the ternary alloy led to boron accumulation on the template surface, which reacted with oxygen during the first stage of Ga2O3 deposition to form a thin amorphous oxide (a-BGaO) at the interface between Ga2O3 and the BGaAs/GaAs template. Again, columnar growth of large [001]-oriented grains of the orthorhombic κ-phase occurred on the amorphous nucleation layers, which resulted in a compact gallium oxide film. These polycrystalline or amorphous interlayers are important as they provide a suitable platform for growth of phase-pure orthorhombic κ-Ga2O3 on III-V cubic substrates. This work paves the way to the integration of κ-Ga2O3 and III-V semiconductors, for preparing heterojunctions for novel electronic and optoelectronic devices
Copper-free chips generate robust ‘combs’ of multicoloured light
No full textA stable ‘frequency comb’ of photons with discrete colours has been generated on a microscale chip by removing copper contaminants from the circuit
Conductive graphitic layers induced in diamond by multi-species focused ion beam
No full textIrradiation of diamond surface by energetic ion beams has represented a useful and flexible technique to modify the material properties in order to comply with quantum technology needs. For instance, ion implantation is a reliable process to create color centers (CCs) in diamond, due to its ability to define their concentration and three dimensional location1, where the ion kinetic energy defines the depth of the implanted species whereas a nanometric lithography can define the lateral positioning. Besides that, ion implantation can also permanently modify the crystallographic phase of diamond. Indeed, if the ion fluence is able to completely amorphize volume of diamond, the hybridized sp3 bonds of diamond are converted to the sp2 configuration and subsequent thermal annealing can only convert the irradiated areas to graphite in an irreversible way2. This effect, clearly detrimental to the formation of CCs, can be useful considering that the graphitic layers are electrically conductive. Therefore, they can be exploited to create integrated or buried conductive layers3, supporting electrical driving of CCs or even creating electrodes for photocurrent detection of magnetic resonance4.
In this work, we report a systematic experiment carried out to produce graphitic layers on ‘electronic grade’ diamonds using a multi-species focused ion beam (FIB) equipment. The lateral resolution of the latter allows to directly write conductive paths on the diamond surface. The installed liquid metal alloy ion source (LMAIS)5 allows to implant Au++, Ge++ and Si++ species with kinetic energy of 70 keV or below. The combination of ion species and implant energies makes possible to tune the graphitic thicknesses. For instance, for 70 keV irradiations graphite thicknesses ranged from 40 to 90 nm. During the experiment, process window was defined for each ion species in terms of ion fluence and thermal annealing, identifying the carbon phases by Raman spectroscopy and measuring by atomic force microscopy the surface swelling after ion irradiation and the removed thicknesses after a selective wet etching. Finally, implications about the possibility of create also CCs during the graphitization itself will be discussed, with particular reference to group IV-vacancy CCs like SiV and GeV6.
References
1. S. Pezzagna, et al. New Journal of Physics 13(3) (2011), 035024.
2. C. Uzan‐Saguy, et al. Appl. Phys. Lett. 67(9) (1995), 1194.
3. F. Picollo, et al. New Journal of Physics 14(5) (2012), 053011.
4. G. Villaret, et al. Appl. Phys. Lett. 122(19) (2023), 194001.
5. L. Bischoff, et al. Appl. Phys. Rev. 3(2) (2016), 021101.
6. C. Bradac, et al. Nat. Comm. 10(1), (2019), 5625
A SiN photonic platform integrated with Si detectors for classical and quantum applications
No full textWe present recent developments of a monolithically integrated Quantum Simulator (QS) platform where the silicon nitride quantum micro-photonic and the mature silicon microelectronic (CMOS, digital) functionalities are merged into a unique photonic-electronic platform. We will describe a 3D-integrated quantum simulator hardware, where (1) photonic quantum interference circuits are integrated on the same Si chip with (2) scalable arrays of single photon avalanche diodes (Silicon SPADs) operating at ~ 800nm and at room temperatures. Around this, we build an integrated system, in which on the “software level” quantum algorithms sustain the quantum simulation results from the hardware. In this last, a custom analog chip controls the QS module by managing the photon source, phase shifters which reconfigure the photonic circuits and the SPADs in order to control actively the quantum optical circuit. Finally, the output data are handled by the digital chip to feed the software algorithm
Overcoming fabrication challanges of color centers in diamond with a focused ion beam
No full textDefects in diamonds such as nitrogen-vacancy (NV), silicon-vacancy (SiV), and germanium-vacancy (GeV) color centers have become extremely important in quantum sensing, quantum communication, and quantum computing technologies, for their remarkable optical and spin properties. This work is focused on the deterministic color center fabrication technique based on ion implantation using a FIB system with a Liquid Metal Alloy Ion Source (LMAIS). This method enables the accurate implantation of several ions (such as Si and Ge) down to the nanometer scale, thus facilitating the precise engineering of color centers without the necessity of elaborate lithographic techniques. Regardless of its benefits, this method offers several challenges in fabrication. One significant challenge is the local amorphization, which occurs when high local ion fluence, resulting from concentrating ions into small regions, damage the diamond lattice and induce amorphization and then graphitization after a thermal annealing process. The damaged areas compromise the quality of the crystal but also leads to additional undesired emitting sources of photons. Furthermore, the mass resolution of the Wien filter can lead to ion cross-contamination, especially when using large or degraded apertures. For instance, Ge and Si cross- contamination may occur, unintentionally forming mixed color center types. Another concern is the implantation of neutral atomic species, which, in systems without dedicated hardware to handle them, can travel undisturbed down the column to the substrate, introducing defects at the center of the writing field. To overcome these issues, we investigate approaches like layout modification, a few guidelines about beam, and a post-implantation protocol to treat the substrates. All these strategies seek to improve the control of defect formation, background noise reduction, and operational dependability of quantum devices that take advantage of diamond color centers
Intra- and inter-annual analysis of remote sensing time series with multitask learning
No full textMultiannual analysis of remote sensing images for monitoring crop rotation, urbanization, or any other type of land cover transition helps to understand Earth dynamics. Existing methods studying images spanning over more than a year mainly focus only on land cover changes. Other methods perform land cover updates, but following a strategy guided by previous available maps and seeking to obtain a new one. Those methods are effective but may omit intra- and inter-annual interdependencies. In this work, we propose to perform multiannual remote sensing analysis using a multitask deep learning strategy that captures interdependencies across multiple objectives and is beneficial for performance and efficiency. The proposed method performs simultaneous intraannual semantic segmentation and inter-annual change detection by analyzing two time series of yearly data. It extracts spatio-temporal information using encoders with shared parameters to ensure robustness and enhance consistency across years and tasks. It further relies on transformer encoder mechanisms in the latent space for extracting global temporal information, and proceeds with separate decoders, outputting segmentation maps for each year, as well as a change map between the years. The model is trained using a multitask loss function. The proposed method captures local and global spatio-temporal information from the annual time series, allowing us to get extensive insights on the data content. Thus, the method is further directly applicable for the task of annual land-cover semantics updating and multitemporal semantic change detection. To validate our approach, we tested the algorithm on Sentinel-2 time series data of agricultural seasons 2021 and 2022, containing crop fields and labeled pixel-wise, examining crop rotation in an area of Austria. With our model architecture, we performed simultaneously the tasks of crop type classification pixel-wise and changed fields detection, and achieved promising results