Fernando Manuel Araújo Moreira

Simulations of quantum-dot-based ionizing radiation detectors require the electronic gap ofthe dots, which enters the light-yield bound, the mean energy per electron–hole pair, and theemission wavelength. For silicon quantum dots, this gap is usually computed on hydrogen-passivated Si𝑛 H𝑚 clusters, whose construction involves geometric and connectivity choices that are rarely reported. An open Python/PySCF protocol that builds and validates such clusters is presented, and the dependence of the structures and of the HOMO–LUMO gap on these choices is quantified for diameters of 0.8–2.0 nm. Only one value of the minimum-coordination criterion, 𝑛_min = 2, changed the structure without emptying the cluster. Directional passivation produced H–H pairs 1.423 Å apart, a distance derived here in closed form; a filling criterion removed them by construction, at a steric cost above 1 eV and with little effect on the gap. The cutting criterion, checked with two basis sets, changed the gap by up to 0.74 eV below 1 nm, three times the size-only estimate. Propagated to detector inputs, it shifts the light-yield bound and the pair-creation energy by 3.5–11% for 0.8–1.5 nm clusters, comparable to the residual basis-set error and larger than the effects of relaxation or density fitting. The protocol also yields models of the typical radiation-induced defect: removing one hydrogen atom leaves a localized dangling bond whose levels lie deep in the gap and roughly halve the effective gap in PBE, several times the construction effects. Geometries and scripts are made available.

As tecnologias quânticas de segunda geração têm se consolidado como um dos ramos de maior capacidade disruptiva do século XXI. Este artigo analisa a produção científica e tecnológica sobre essas tecnologias, com foco em sua aplicação na defesa. Para tal, utilizou-se abordagem quantitativa baseada em dados das bases Scopus e PATENTSCOPE, adotando taxonomias internacionalmente reconhecidas – relatório Strategic Research and Industry Agenda (SRIA 2030) for Quantum Technologies da iniciativa Quantum Flagship da Comissão Europeia, sistema de classificação da Association for Computing Machinery (ACM), taxonomia do Institute of Electrical and Electronics Engineers (IEEE) e categorização da Divisão de Ciência e Tecnologia da OTAN. Os resultados mostram que a produção científico-tecnológica em tecnologias quânticas, entre 2014 e 2024, apresentou crescimento expressivo, sobretudo após 2021, com liderança de China e EUA e participação modesta do Brasil. A produção científica da Índia cresce de forma destacada, principalmente na vertente da defesa. Semelhanças foram observadas nas áreas de pesquisa entre os cenários global e militar, com destaque para computação e comunicações quânticas. Quanto às áreas de aplicação, apesar da baixa representatividade da defesa, sua produção apresenta tendência de crescimento superior à do contexto global, sugerindo progressivo interesse no setor. As aplicações de tecnologias quânticas na defesa que mais recebem atenção são C4ISR (controle, comando, comunicações, computadores, inteligência, vigilância e reconhecimento) & apoio à decisão e hipersônica & espaço. A partir dessa análise, o estudo prospecta o desenvolvimento de soluções no contexto do Exército Brasileiro.

Nanostructured carbon materials are low-dimensional systems relevant to oncology biosensing, with their utility arising from an electronic structure coupled to defect and edge states, a charge-transfer behavior and optical response that report molecular binding, an interfacial chemistry governing contact with the analyte, and, in selected cases, magnetic properties enabling manipulation and readout. In functional terms, these behaviors trace to specific quantum-relevant features—quantum confinement, edge and defect states, and the resulting size-dependent optical and charge-transfer responses—rather than to a generic quantum-material designation. This critical review treats nanocarbons as engineered biointerfaces whose performance is set by how the carbon surface behaves in biological fluid, how recognition chemistry is anchored, and how the binding event is transduced, with magnetic responsiveness, stability, reproducibility, and fabrication control as decisive constraints. The analysis separates three material classes—non-magnetic nanocarbon sensors, hybrid carbon–magnetic systems, and defect-associated or potentially metal-free magnetic carbons—while grading evidence as direct, adjacent, comparator-derived, or prospective. Directly, graphene, carbon nanotubes, carbon dots, graphene quantum dots, and magnetic carbon hybrids serve in electrochemical, optical and fluorescent, field-effect, and magnetic-assisted formats. Clinical translation, however, remains constrained by biofouling, protein-corona formation, matrix interference, unstable functionalization, batch variability, incomplete standardization, and scarce validation in real samples and patient cohorts. Metal-free or defect-associated magnetic carbons therefore warrant caution, remaining prospective platforms until the preservation of magnetic response, reproducible functionalization, matrix compatibility, safety, and measurable analytical advantage are directly demonstrated.

Low-angle twisted bilayer graphene (TBG) reconstructs into a heterogeneous moiré mosaic of Bernal (AB/BA) domains separated by soliton (SP) walls, hosting twist-angle-sensitive correlated phases. Thermal annealing is routine in van der Waals device processing and can reorganize this mosaic, yet no non-invasive, far-field optical method has been shown to monitor this reorganization reproducibly. Here we develop a pixel-by-pixel confocal Raman mapping workflow, based on G- and 2D-band descriptors and 2D-band deconvolution, that segments the twisted domain into three operational regions (S, M, and N) and tracks their thermally driven evolution without the specialized instrumentation required by near-field or transport probes. We apply it to an hBN-encapsulated TBG device at room temperature after successive anneals from 25 to 500 ºC, extracting region-resolved trajectories of I2D/IG, ΓG, and an effective twist field θ(r). The most responsive region, S (θ ≈ 1.00º), displays a multicomponent G-band profile and undergoes a sharp reorganization between 100 and 200 ºC, with ΓG dropping from ~30 to ~24~cm-1. S then converges to θ ≈ 0.80º, while M (θ ≈ 0.75º) exhibits the smallest drift of all descriptors across the annealing sequence. In the ω2D-ωG correlation map, the evolution proceeds predominantly along a strain-like direction with secondary, non-monotonic hole-doping-like modulation. Our results quantify the thermal stability and irreversibility of moiré superlattices in spatially inhomogeneous TBG, supporting screening, quality control, and the definition of processing windows in twistronic workflows.

Nano-carbon biointerfaces offer versatile platforms for cancer biomarker detection, but their progression from analytical proof-of-concept to clinically usable diagnostic evidence remains uneven. This scoping review maps 191 primary studies published from 2024 to 2026, covering nano-carbon families, surface chemistries, transduction architectures, biological matrices, and translational endpoints in cancer biosensing. The evidence space spans four nano-carbon dimensional classes: zero-dimensional carbon dots and quantum dots, one-dimensional carbon nanotubes, two-dimensional graphene-derived materials, and three-dimensional hybrid composites. Across these platforms, analytical sensitivity did not scale monotonically with nano-carbon dimensionality; instead, performance was shaped by the interaction between material architecture, biointerface chemistry, recognition strategy, transduction modality, and matrix context. A Translational Readiness Matrix showed that approximately 67% of studies remained at Low Evidence Level, whereas only approximately 10% reached Strong Evidence Level. Five recurring bottlenecks constrained translation: incomplete reproducibility reporting, limited Real-matrix Validation, scarce comparator-based clinical evidence, insufficient manufacturing-scale data, and weak regulatory or deployment planning. To address these gaps, this review proposes a nine-item minimum reporting checklist and a four-stage validation roadmap to support more reproducible, comparable, and clinically oriented nano-carbon biosensor development.

Introducción: este artículo parte de la premisa de que la denominada “segunda revolución cuántica” está reconfigurando las bases tecnológicas del poder marítimo, y que el dominio submarino se consolida como un espacio estratégico emergente en el marco de la denominada “guerra de los fondos marinos” y de la oceanopolítica contemporánea. Objetivo: clasificar jerárquicamente y analizar el estado del arte y las principales tendencias del sensoreo cuántico aplicado al ambiente submarino entre 2018 y 2025, con foco en las dimensiones técnicas, estratégicas y oceanopolíticas. Metodología: la revisión de alcance identifica las tecnologías recientes de sensoreo cuántico. A partir de esta revisión se realizó un análisis estratégico-oceanopolítico orientado a definir posibles escenarios de futuro en este campo. Conclusiones: los resultados indican que los magnetómetros OPM presentan la trayectoria más prometedora en términos de madurez tecnológica (TRL). El sensoreo cuántico tenderá a complementar las capacidades clásicas de vigilancia submarina, prospección mineral y protección de infraestructuras críticas. Su desarrollo posee una elevada motricidad estratégica en las disputas oceanopolíticas. Finalmente, la ocupación cognitiva del entorno marítimo experimentará transformaciones, con implicaciones para la gobernanza oceánica.

Continuous-Variable Quantum Key Distribution (CV-QKD) offers practical advantages for secure communication, but laser linewidth-induced phase noise remains a critical performance limitation. This work presents a comprehensive simulation-based analysis quantifying the impact of laser linewidth on secret key rate (SKR) in Gaussian-modulated coherent-state CV-QKD systems. We develop a detailed noise model incorporating detector electronics, Raman scattering, phase recovery, ADC quantization, and laser relative intensity noise. Through systematic parameter sweeps spanning linewidths from 10 Hz to 250 kHz, modulation variances from 1 to 20 SNU, and fiber distances up to 100 km, we identify three distinct operational regimes and optimization strategies for both transmitted local oscillator (TLO) and local–local oscillator (LLO) configurations under homodyne and heterodyne detection. Results show that metropolitan-scale links (50 km) require linewidths below 5 kHz to maintain secure operation, with performance decreasing beyond 25 kHz. We demonstrate that modulation variance must be jointly optimized with laser quality, with optimal values decreasing from 3–4 SNU at narrow linewidths to 2–2.5 SNU at moderate linewidths. The analysis reveals asymmetric sensitivity in LLO systems where local oscillator linewidth degrades performance more strongly than signal laser linewidth. These quantitative findings provide practical design guidelines for achieving secure CV-QKD operation over metropolitan distances with realistic hardware constraints, supporting deployment of defense-grade quantum communication networks.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are foundational materials for next-generation electronics. For their viable use in space, nuclear, and medical applications, a comprehensive understanding of their response to high-energy ionizing radiation is critical. This review synthesizes and critically analyzes 32 experimental studies published since 2016 to build a unified framework for γ-radiation effects in TMDs. We found that the primary defect mechanism is the creation of chalcogen vacancies (CVs). The subsequent material response is decisively modulated by the irradiation environment: in ambient air, CVs are passivated, leading to oxidation, whereas in a vacuum or inert gas, pure vacancy effects dominate. This dichotomy resolves apparent contradictions in the literature regarding electronic doping; for instance, WSe₂ consistently exhibits intrinsic n-type doping (from V_Se), while WS₂ and MoS₂ in air trend toward p-type doping (from charge-transfer to oxides). These competing mechanisms of doping, strain, and disorder are mapped to their complex spectroscopic signatures in Raman and photoluminescence, including nonmonotonic dose-dependence. Beyond damage, γ-rays are shown to be a potent tool for defect engineering, inducing emergent properties such as room-temperature ferromagnetism (attributed to V_1M+2S complex vacancies) and optimizing catalytic activity. Finally, this review finds that TMD-based devices possess high intrinsic radiation hardness, with most failures originating from charge trapping in the adjacent dielectrics, not the 2D channel. We conclude by identifying critical gaps in the literature, including the unexplored effects of dose rates and the need for in situ characterization.