HAL Portal IOGS (nstitut d'Optique Graduate School)
Not a member yet
12589 research outputs found
Sort by
SENSE-LM : une synergie entre modèles de langage et représentations sensorimotrices pour la recherche de références olfactives et auditives dans des documents écrits
No full textInternational audienceLes cinq sens – la vue, le goût, l'odorat, l'ouïe et le toucher – influencent la perception humaine à travers diverses modalités. L'extraction de références sensorielles (expressions évoquant une expérience sensorielle) dans un corpus textuel est un sujet d'intérêt avec de nombreuses applications, notamment en neurosciences ou dans l'étude du patrimoine culturel. Cet article présente SENSE-LM, un système d'extraction d'informations sensorielles dans de grandes collections de documents textuels. En associant des modèles de langage et des représentations sensorimotrices, il automatise l'extraction d'informations sensorielles à gros grain (classification binaire de phrases) et à grain fin (extraction de termes sensoriels). L'évaluation de SENSE-LM sur deux sensorialités, l'odorat et l'ouïe, révèle des avancées significatives dans l'automatisation de ces tâches complexes
Transformer neural networks and quantum simulators: a hybrid approach for simulating strongly correlated systems
No full textInternational audienceOwing to their great expressivity and versatility, neural networks have gained attention for simulating large two-dimensional quantum many-body systems. However, their expressivity comes with the cost of a challenging optimization due to the in general rugged and complicated loss landscape. Here, we present a hybrid optimization scheme for neural quantum states (NQS) that involves a data-driven pretraining with numerical or experimental data and a second, Hamiltonian-driven optimization stage. By using both projective measurements from the computational basis as well as expectation values from other measurement configurations such as spin-spin correlations, our pretraining gives access to the sign structure of the state, yielding improved and faster convergence that is robust w.r.t. experimental imperfections and limited datasets. We apply the hybrid scheme to the ground state search for the 2D transverse field Ising model and the 2D dipolar XY model on and square lattices with a patched transformer wave function, using numerical and experimental data from a programmable Rydberg quantum simulator [Chen et al., Nature 616 (2023)], with snapshots of the quantum system obtained from the different measurement configurations, and show that the information from the second basis highly improves the performance. Our work paves the way for a reliable and efficient optimization of neural quantum states
Spectroscopy of elementary excitations from quench dynamics in a dipolar XY Rydberg simulator
No full textInternational audienceWe use a Rydberg quantum simulator to demonstrate a new form of spectroscopy, called quench spectroscopy, which probes the low-energy excitations of a many-body system. We illustrate the method on a two-dimensional simulation of the spin-1/2 dipolar XY model. Through microscopic measurements of the spatial spin correlation dynamics following a quench, we extract the dispersion relation of the elementary excitations for both ferro- and anti-ferromagnetic couplings. We observe qualitatively different behaviors between the two cases that result from the long-range nature of the interactions, and the frustration inherent in the antiferromagnet. In particular, the ferromagnet exhibits elementary excitations behaving as linear spin waves. In the anti-ferromagnet, spin waves appear to decay, suggesting the presence of strong nonlinearities. Our demonstration highlights the importance of power-law interactions on the excitation spectrum of a many-body system
Straightforward Method to Orient Black Phosphorus from Bulk to Thin Layers using a Standard Green Laser
No full textInternational audienceThe crystallographic orientation of anisotropic 2D materials plays a crucial role in their physical properties and device performance. However, standard orientation techniques such as transmission electron microscopy (TEM) or X‐ray diffraction can be complex and less accessible for routine characterization. Herein, the orientation of black phosphorus (BP) from bulk crystals to thin layers is investigated using angle‐resolved polarized Raman spectroscopy with a single‐wavelength (514 nm) Raman setup. By incorporating thickness‐dependent interference effects and anisotropic optical indices, this approach provides a reliable framework for orientation determination across different BP thicknesses. The method is validated through direct orientation measurements using TEM and electron backscattering diffraction, confirming its applicability to both thick and ultrathin samples. Given its simplicity and compatibility with widely available Raman setups, this approach offers a practical solution for characterizing BP orientation without requiring advanced structural characterization techniques
Metrology studies for high precision astrometry in Theia / HWO
No full textInternational audienceThis presentation outlines ongoing metrology developments enabling micro-arcsecond precision for future astrometry missions such as Theia (ESA M8) and HWO (NASA). We describe differential astrometry concepts relying on precise detector calibration using interferometric fringes and distortion monitoring through dense Gaia reference fields. Laboratory tests with large-format Pyxalis CMOS detectors demonstrate promising radiometric and interferometric performance. Initial distortion-calibration simulations confirm the feasibility of achieving sub-micro-pixel accuracy. These results support the technological readiness required for detecting Earth-mass planets and probing dark matter through ultra-precise stellar motions
Polychromie. Regards croisés sur l’usage, l’emploi et la matérialité de la polychromie dans les sociétés anciennes
No full textInternational audienceSince 1990, research into historic dyes has added considerably to our knowledge of the colour palettes and techniques of ancient societies. Thanks to scientific advances and modern analysis tools, it is now possible to identify, characterise and restore certain lost colours. Despite this progress, some grey areas remain: were all the parts of ancient buildings painted? Was statuary polychromy intended to imitate the living world, or did it reflect an aesthetic specific to the context in which it was displayed? These questions, as well as the techniques used to enhance sculpture (folds, contours, etc.), require an interdisciplinary approach.In June 2024, an international study day brought together archaeologists, art historians, materials specialists and computer scientists to take stock of these issues. The book that emerged from this meeting takes stock of current research into the use and application of colouring materials from our historical heritage, highlights the methodological challenges, and underlines the contribution of digital technology to the faithful reproduction of these colours altered by time.Depuis 1990, les recherches sur les colorants du patrimoine historique ont considérablement enrichi nos connaissances sur les palettes et les techniques chromatiques des sociétés anciennes. Grâce aux avancées scientifiques et aux outils d’analyse modernes, il est désormais possible d’identifier, caractériser et restituer certaines couleurs disparues. Malgré ces progrès, des zones d’ombre persistent : toutes les parties des édifices anciens étaient-elles peintes ? La polychromie statuaire visait-elle à imiter le vivant ou relevait-elle d’une esthétique spécifique au contexte d’exposition ? Ces questionnements, ainsi que les techniques de mise en valeur sculpturale (plis, contours, etc.), nécessitent une approche interdisciplinaire.En juin 2024, une journée d’étude internationale a réuni archéologues, historiens de l’art, spécialistes des matériaux et informaticiens pour faire le point sur ces problématiques. L’ouvrage issu de cette rencontre dresse un état des lieux des recherches actuelles sur l’usage et l’emploi des matières colorantes issues du patrimoine historique, met en lumière les défis méthodologiques, et souligne l’apport du numérique dans la restitution fidèle de ces couleurs altérées par le temps
Noise budget of a trapped on-chip cold-atom Rb 87 clock
No full textInternational audienceIn this paper, we present a realization of an on chip atomic clock using a cold cloud of rubidium 87 atoms. This clock is based on a Ramsey interferometer with a Ramsey time around 600 ms. This is realized with large laboratory temperature drift during the measurement (few degrees per day) and without magnetic-field shielding. We review the experimental implementation of this clock and give a full study of the known noises present in this atomic clock.</div
Dynamics of one-dimensional Bose gas revealed by measuring the local rapidity distribution
No full textInternational audienc
Application d’une lentille à Jet Électromagnétique à la détection et la caractérisation de défauts enfouis
No full textInternational audienc
A new method to optimize measurement conditions for fluorescence spectroscopy systems for intraoperative glioma delineation
No full textInternational audience5-ALA-induced PpIX fluorescence has been proposed to improve the identification of benign from malignant brain tumors during surgery. Based on simulation, this work helps at determining the best operating measurement conditions for estimating PpIX concentration