HAL Portal IOGS (nstitut d'Optique Graduate School)
Not a member yet
12589 research outputs found
Sort by
High-fidelity collisional quantum gates with fermionic atoms
No full text16 pages, 18 figuresQuantum simulations of electronic structure and strongly correlated quantum phases are widely regarded as among the most promising applications of quantum computing. These simulations require the accurate implementation of motion and entanglement of fermionic particles. Instead of the commonly applied costly mapping to qubits, fermionic quantum computers offer the prospect of directly implementing electronic structure problems. Ultracold neutral atoms have emerged as a powerful platform for spin-based quantum computing, but quantum information can also be processed via the motion of bosonic or fermionic atoms offering a distinct advantage by intrinsically conserving crucial symmetries like electron number. Here we demonstrate collisional entangling gates with fidelities up to 99.75(6)% and lifetimes of Bell states beyond via the control of fermionic atoms in an optical superlattice. Using quantum gas microscopy, we characterize both spin-exchange and pair-tunneling gates locally, and realize a robust, composite pair-exchange gate, a key building block for quantum chemistry simulations. Our results enable the preparation of complex quantum states and advanced readout protocols for a new class of scalable analog-digital hybrid quantum simulators. Once combined with local addressing, they mark a key step towards a fully digital fermionic quantum computer based on the controlled motion and entanglement of fermionic neutral atoms
Effects of Gamma Irradiation on Solid Propellant Conventional and UV-Cured Binders
No full textInternational audienceIonizing radiations are responsible for bond scission, radical formation, and oxidative degradation of polymer matrices. This study focuses on the effects of gamma irradiation on solid propellant binders, targeting a comprehensive chemical and mechanical characterization of different formulations. Samples were produced either by conventional methods based on hydroxyl-terminated polybutadiene and standard polyaddition reaction using isocyanates, or innovative approaches involving UV-driven radical curing. The samples were irradiated for comparison and to study their evolution as a function of three absorbed doses (25, 45, 130 kGy) for preliminary characterization studies, using a 60-Co gamma source. Samples were irradiated in air at uncontrolled room temperature. The coupling of spectroscopy techniques (Fourier transform infrared—FTIR, Raman and electron paramagnetic resonance—EPR) and dynamic mechanical analysis (DMA) highlighted the key role of antioxidant agents in tailoring mechanical changes in the binder phase. The absence of antioxidants enhances radical formation, oxidation, and cross-linking. These processes lead to progressively increased rigidity and reduced flexibility as a function of the absorbed dose. Complex interactions between photocured components largely influence radical stabilization and material degradation. These findings provide valuable insights for designing novel radiation-resistant binders, enabling the development of solid propellants tailored for reliable, long-term permanence in space, and advancing the knowledge on the applicability of 3D-printed propellants
Masked Computation of the Floor Function and Its Application to the FALCON Signature
No full textInternational audienceFALCON is a signature selected for standardisation of the new Post-Quantum Cryptography (PQC) primitives by the National Institute of Standards and Technology (NIST). However, it remains a challenge to define efficient countermeasures against side-channel attacks (SCA) for this algorithm. FALCON is a lattice-based signature that relies on rational numbers, which is unusual in the cryptography field. Although recent work proposed a solution to mask the addition and the multiplication, some roadblocks remain, most noticeably, how to protect the floor function. In this work, we propose to complete the first existing tests of hardening FALCON against SCA. We perform the mathematical proofs of our methods as well as formal security proofs in the probing model by ensuring Multiple Input Multiple Output Strong Non-Interference (MIMO-SNI) security. We provide performances on a laptop computer of our gadgets as well as of a complete masked FALCON. We notice significant overhead in doing so and discuss the deployability of our method in a real-world context
Experimental tests of the calibration of high precision differential astrometry for exoplanets
No full textInternational audienceHigh precision differential Astrometry is the branch of astronomy that evaluates the relative position, distance and motion of celestial objects with respect to the stars present in the field of view. A mission called Theia has been submitted in 2022 for ESA's M7 call for missions, using a diffraction-limited telescope about 1m in diameter and with a field of view of 0.5 degrees, capable of achieving sub-micro-arcsecond angular accuracy, corresponding to 1e-5 pixel on the detector. Such precision makes it possible to study the nature of dark matter in our galaxy and to reveal the architecture of exoplanetary systems close to the Sun, down to the mass of the Earth. The aim of the experimental tests is to improve the TRL of 2 specific aspects: the calibration of new CMOS detectors with very large number of pixels and the calibration of the telescope aberrations.First, a key element of such a space telescope is the focal plane, which must be calibrated spatially with an extreme precision down to the 1e-5 pixel level. Previous work has shown that this is possible with small detector matrices (80x80 px). The goal is now to check the performances and validate this method with the new very large detectors. Pyxalis, a company based near Grenoble, is developing very large detectors (8000x5000 px) that have a low noise level and high sensitivity. The aim is to characterize and validate this type of detectors in a laboratory demonstration, to ensure that the performance achieved meets the required specifications. We present the results of these characterization in this contribution.The telescope stability is also a sensitive issue. Recent work has shown that the reference stars in the field of the telescope can be used as actual metrology sources in order to compute the field distortion function. Our simulations allow to model the optical aberrations with bivariate polynoms. The effects on the calibration accuracy of the degrees of the polynoms, the number of reference stars and the tilt perturbation of the M2 mirror are investigated. This paper will present the latest results obtained on a test bed developed to experimentally study the performances of this new field calibration method
Photobleaching Effects on the Radiation-Induced Attenuation of Germanosilicate Optical Fibers at Low Temperature
No full textInternational audienc
Dispersion‐Less Dissipative Soliton Fiber Laser
No full textInternational audienceABSTRACT Dispersion engineering has been instrumental in promoting, through intracavity pulse stretching, the generation of higher‐energy mode‐locked pulses. Such approach requires extra‐cavity compression and struggles to deliver bell‐shaped pulses. However, in the context of dissipative solitons, it is also possible to generate energetic, pedestal‐free pulses in the quasi‐absence of dispersive linear effects. We achieve the latter by tailoring picosecond pulses through spectral filtering, inspired by the recently reported energy‐managed soliton laser architecture. The present dispersion‐less energy‐managed mode‐locked fiber laser demonstrates remarkable flexibility in both pulse energy and duration. Its experimental validation, using standard telecom components in the telecom window, yields mode‐locked pulses of up to at a repetition rate of 1.9 MHz. We introduce an additional energy scaling by incorporating a few‐mode gain fiber to generate pulses featuring low spectral distortion
Couleurs structurelles de métasurfaces plasmoniques désordonnées : théorie et simulation
No full textNational audienceNous présentons un modèle théorique pour prédire les couleurs structurelles observées en réflexion spéculaire de monocouches de nanoparticules métalliques intégrées dans des empilements de couches minces. Ce modèle repose sur l’approximation quasi-cristalline, qui prend en compte les corrélations spatiales entre particules dans le cadre de la diffusion multiple. Sa validité est confirmée par comparaison avec des calculs numériques rigoureux basés sur la méthode de la matrice T
Optimization of laser-induced printed colors for industrial applications
No full textInternational audienc
Terahertz Synthetic Aperture-based Spatiotemporal Imaging
No full textInternational audienceTerahertz (THz) microscopy has garnered significant attention due to the unique properties of THz radiation, making it appealing for chemical sensing, biomedical diagnostics, and imaging of complex media applications. However, conventional THz imaging systems encounter fundamental resolution limitations due to the Rayleigh diffraction limit. To overcome this challenge, we propose an innovative theoretical and numerical framework by adopting Fourier synthetic aperture principles in the THz spectral range. Our approach synthesizes high spatial frequency components by illuminating the sample with broadband THz pulses from multiple angles and capturing the time-resolved scattered fields through state-of-the-art timedomain spectroscopy (TDS). Our method offers a field-sensitive and experimentally viable solution for surpassing the diffraction limit in THz imaging. It paves the way for high-resolution, labelfree material characterization and noninvasive imaging across various domains, including materials science, biomedical imaging, and security screening.</div
Pièce métallique structurée par irradiation laser pour dispositif de transport et/ou de stockage et/ou de fabrication d’hydrogène
No full textDonnées bibliographiques: WO2025224136 (A1) ― 2025-10-30Numéro(s) de priorité : FR20240004172 ―2024-04-23 Demandeur : Institut Mines Telecom [FR] ; Centre national de la recherche scientifique (CNRS) [FR] ; Université Jean Monnet Saint-Etienne [FR]International audienceDisclosed is a metal part (100) comprising a surface (112) with low hydrogen permeability. Also disclosed is a method for structuring such a part (100) by femtosecond laser irradiation.Pièce (100) métallique comprenant une surface (112) à perméabilité réduite à l’hydrogène. Procédé de structuration d’une telle pièce (100) par irradiation laser femtoseconde