Broadband spin-unlocked achromatic meta-devices empowered by hybrid-phase cooperative dispersion engineering

Suppression of synchronous current of active magnetic bearings considering radial displacement inconsistency

We show that arbitrarily high-order exceptional points (EPs) can be achieved\nin a repulsively interacting two-species Bose gas in one dimension. By exactly\nsolving the non-Hermitian two-boson problem, we demonstrate the existence of\nthird-order EPs when the system is driven across the parity-time symmetry\nbreaking transition. We further address the fourth-order EPs with three bosons\nand generalize the results to $N$-body system, where the EP order can be as\nhigh as $N+1$. Physically, such high order originates from the intrinsic\nferromagnetic correlation in spinor bosons, which renders the entire system\ncollectively behave as a single huge spin. Moreover, we show how to create\nultra-sensitive spectral response around EPs via an interaction anisotropy in\ndifferent spin channels. Our work puts forward the possibility of atomic\nsensors made from highly controllable ultracold gases.\n

On the feasibility of large vapor-compression distillation units

Structural health monitoring commonly uses natural frequency analysis to assess structural conditions, but direct frequency shifts are often insensitive to minor damage and susceptible to environmental influences like temperature variations. Traditional methods, whether based on absolute frequency changes or theoretical models like PCA and GMM, face challenges in robustness and reliance on model selection. These limitations highlight the need for a more adaptive and data-driven approach to capturing the intrinsic nonlinear correlations among multi-order modal frequencies. This study proposes a novel approach that leverages the nonlinear correlations among multi-order natural frequencies, which are more sensitive to structural state changes. A deep learning framework integrating CNN-BiLSTM-Attention is designed to capture the spatiotemporal dependencies of multi-order frequency data, enabling the precise modeling of intrinsic correlations. The model was trained exclusively on healthy-state frequency data and validated on both healthy and damaged conditions. A probabilistic modeling approach, incorporating Gaussian distribution and cumulative probability functions, was used to evaluate the estimation accuracy and detect correlation shifts indicative of structural damage. To enhance the robustness, a moving average smoothing technique was applied to reduce random noise interference, and damage identification rates over extended time segments were calculated to mitigate transient false alarms. Validation experiments on a mass-spring system and the Z24 bridge dataset demonstrated that the proposed method achieved over 95% damage detection accuracy while maintaining a false alarm rate below 5%. The results validate the ability of the CNN-BiLSTM-Attention framework to effectively capture both structural and environmental nonlinearities, reducing the dependency on explicit theoretical models. By leveraging multi-order frequency correlations, the proposed method provides a robust and highly sensitive approach to structural damage identification. These findings confirm the practical applicability of deep learning in damage identification during the operational phase of structures.

International audience

This paper presents the OTHex platform for aerial manipulation developed at LAAS-CNRS. The OTHex is probably the first multi-directional thrust platform designed to act as Flying Assistant which can aid human operators and/or Ground Manipulators to move long bars for assembly and maintenance tasks. The work emphasis is on task-driven custom design and experimental validations. The proposed control framework is built around a low-level geometric controller, and includes an external wrench estimator, an admittance filter, and a trajectory generator. This tool gives the system the necessary compliance to resist external force disturbances arising from contact with the surrounding environment or to parameter uncertainties in the load. A set of experiments validates the real-world applicability and robustness of the overall system.

Large-amplitude current modulation of semiconductor laser and multichannel optical imaging

Metal oxides have attracted attention as catalysts for various reduction and oxidation reactions due to their abundance, inexpensiveness, and the possibility of combining different catalytic sites (e. g., acid‐base, redox, and oxygen vacancy sites). Previous results have demonstrated that metal oxides are promising candidates for the hydrodeoxygenation (HDO) reaction, one of the processes that aim to upgrade biomass‐derived products by reducing their oxygen content. In this work, molybdenum oxide (MoO3) was subjected to the acetone HDO reaction leading to new insights concerning the generation of molybdenum oxycarbides (MoOxCy) on stream and their catalytic properties. The characteristics of the MoOxCy phase depended on the temperature and time on stream, affecting the balance of the different catalytic sites and the final products’ distribution. The intrinsic correlation between the active sites – mainly Brønsted/Lewis acid sites (AS) and hydrogenation/hydrogenolysis sites (HS) – and the reaction pathways was discussed in detail.

Development of a travelling/standing wave switching acoustic manipulation platform for ICF capsules rotation and sorting.

This letter proposes a multichannel optical fiber spectral and imaging system, aiming at evaluating the pixel-level optical properties of high definition display efficiently and precisely. The system makes use of 16-channel optical fibers to form a detecting array so that 16 points of a display under test can be measured cyclically by multiplexer and spectrometer and monitored by camera simultaneously. The optical path is reversible for both the light source and the laser positioning, and adjustable along a rail driven by a motor to enable the system to work in either magnification mode or reduction mode. The feasibility and accuracy of the system are verified by comparative experiments of standard light source, LED display, and OLED display, identifying both merits of a single-spot spectroradiometer and an imaging photometer/colorimeter and even more functions like pitch size and color gamut.

Mid-infrared (MIR) spectroscopy serves as a powerful tool for molecular structure identification and chemical composition analysis. However, conventional Fourier-transform infrared spectrometers (FTIR) demonstrate compromised signal-to-noise ratios (SNR) under low-light conditions, which severely limit their performance in high-sensitivity applications. Although MIR superconducting nanowire single-photon detectors (SNSPDs) offer high detection efficiency and low timing jitter, their performance is hindered by background dark counts caused by room-temperature blackbody radiation. In this work, we present a quantum-correlated absorption spectroscopy platform that combines MIR-SNSPDs with entangled photon pairs to overcome these limitations. Leveraging the intrinsic temporal and spectral correlations of the photon pairs, coincidence detection effectively distinguishes signal photons from dominant thermal noise, achieving a remarkable improvement of two orders of magnitude in SNR under ultralow pump power conditions. The system achieves a spectral coverage of 3350-3540 nm with a resolution of 3.7 cm-1 at 3.4 µm, operating at an ultralow illumination photon flux of 4.4 × 106 photons/s. Validation experiments using polystyrene and polyethylene samples successfully detected CH2 vibrational modes, demonstrating the platform's capability for ultrasensitive biochemical analysis and material characterization. By integrating quantum correlation with MIR-SNSPDs, this work establishes a new paradigm for high-performance MIR spectroscopy in low-light scenarios.

Vectorial vortex beam detection using plasmonic interferences on a structured gold film

Vortex beams, characterized by orbital angular momentum (OAM), hold significant potential in optical communications, quantum information processing, and optical manipulation. However, existing metasurface designs are largely confined to single-degree-of-freedom control, such as static OAM generation or fixed focal points, which limiting their ability to integrate polarization multiplexing with dynamic focal tuning. To address this challenge, we propose a tunable multifunctional cascaded metasurface that synergizes polarization-sensitive phase engineering with interlayer rotational coupling, overcoming conventional device limitations. The designed metasurface independently generates distinct OAM states in orthogonal circular polarization channels under right-handed circularly polarized (RCP) incidence, that is, a vortex beam with topological charge ℓ = −1 in the left-handed circularly polarized (LCP) channel and a superimposed vortex state (ℓ = +1, −1) in the RCP channel. Continuous focal tuning is achieved via interlayer rotation in the axis-direction, with experimental validation at target frequency. Experimental results demonstrate the focal length modulation range from 25.9λ to 9.5λ as the interlayer rotation angle varies between 90° and 240°. This multi-degree-of-freedom control strategy establishes a new method for high-capacity optical communications, dynamic holography, and quantum state manipulation, while advancing the development of intelligent metasurfaces for 6G networks and integrated photonic systems.

ABSTRACTBackground and Purpose. Talairach‐based parcellation (TP) of human brain magnetic resonance imaging (MRI) data has been used increasingly in clinical research to make regional measurements of brain structures in vivo. Recently, TP has been applied to pediatric research to elucidate the changes in regional brain volumes related to several neurological disorders. However, all freely available tools have been designed to parcellate adult brain MRI data. Parcellation of neonatal MRI data is very challenging owing to the lack of strong signal contrast, variability in signal intensity within tissues, and the small size and thus difficulty in identifying small structures used as landmarks for TP. Hence the authors designed and validated a new interactive tool to parcellate brain MRI data from newborns and young infants. Methods. The authors' tool was developed as part of a postprocessing pipeline, which includes registration of multichannel MR images, segmentation, and parcellation of the segmented data. The tool employs user‐friendly interactive software to visualize and assign the anatomic landmarks required for parcellation, after which the planes and parcels are generated automatically by the algorithm. The authors then performed 3 sets of validation experiments to test the precision and reliability of their tool. Results. Validation experiments of intra‐and interrater reliability on data obtained from newborn and 1‐year‐old children showed a very high sensitivity of >95% and specificity >99.9%. The authors also showed that rotating and reformatting the original MRI data results in a statistically significant difference in parcel volumes, demonstrating the importance of using a tool such as theirs that does not require realignment of the data prior to parcellation. Conclusions. To the authors' knowledge, the presented approach is the first TP method that has been developed and validated specifically for neonatal brain MRI data. Their approach would also be valuable for the analysis of brain MRI data from older children and adults.

Vortex beams with orbital angular momentum (OAM) exhibit immense potential in various fields such as communications, information processing, and optical tweezers. Nevertheless, current terahertz vortex beam generators still face challenges including narrow frequency bands, low efficiency, limited multiplexing capabilities, and difficulties in dynamic tuning. Here, the study introduces a new electrically controlled multi‐channel multiplexing strategy that harnesses cascaded helical geometric metasurface, liquid crystal (LC) layer, and OAM‐based metalens to achieve comprehensive and independent phase manipulation across all four spin channels. Moreover, by employing spin, spatial, OAM multiplexing, and the LC active control technology, eight distinguishable spin angular momentum (SAM)‐OAM coupling states are decoded, enabling dynamic control of vortex beams with 6 different topological charges. Experimental validation reveals remarkable performance: within the broadband range of 0.4–0.6 THz, the vortex beams exhibit a peak excitation efficiency of up to 94%, with each mode purity reaching its highest level of >80%, and the minimum value of inter‐mode coupling crosstalk is <–11 dB. This terahertz vortex beam generation and conversion mechanism enhances the operational flexibility in light field manipulation, breaking through the limitations of channel multiplexing and dynamic manipulation in the terahertz band, pioneering a novel avenue for bolstering parallel processing, mitigating inter‐channel crosstalk.