HAL Portal IOGS (nstitut d'Optique Graduate School)
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Rearrangement of individual atoms in a 2000-site optical-tweezer array at cryogenic temperatures
No full textInternational audienceWe report on the trapping of single rubidium atoms in large arrays of optical tweezers comprising up to 2088 sites in a cryogenic environment at 6 K. Our approach relies on the use of microscope objectives that are in vacuum but at room temperature, in combination with windowless thermal shields into which the objectives are protruding to ensure a cryogenic environment for the trapped atoms. To achieve enough optical power for efficient trapping, we combine two lasers at slightly different wavelengths. We discuss the performance and limitations of our design. Finally, we demonstrate atom-by-atom rearrangement of an 828-atom target array using moving optical tweezers controlled by a field-programmable gate array
Tailoring the superradiant and subradiant nature of two coherently coupled quantum emitters
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Micro fabrication of III-V based solar cells for weight reduction and performance improvement
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Observation of heat pumping effect by radiative shuttling
No full textInternational audienceAbstract Heat shuttling phenomenon is characterized by the presence of a non-zero heat flow between two bodies without net thermal bias on average. It was initially predicted in the context of nonlinear heat conduction within atomic lattices coupled to two time-oscillating thermostats. Recent theoretical works revealed an analog of this effect for heat exchanges mediated by thermal photons between two solids having a temperature dependent emissivity. In this paper, we present the experimental proof of this effect using systems made with composite materials based on phase change materials. By periodically modulating the temperature of one of two solids we report that the system akin to heat pumping with a controllable heat flow direction. Additionally, we demonstrate the effectiveness of a simultaneous modulation of two temperatures to control both the strength and direction of heat shuttling by exploiting the phase delay between these temperatures. These results show that this effect is promising for an active thermal management of solid-state technology, to cool down solids, to insulate them from their background or to amplify heat exchanges
New Terminological Approaches for New Heritages and Corpora: The ITinHeritage Project
No full textInternational audienceSafeguarding Information Technology (IT) heritage is a matter of general interest. This is the aim of the ITinHeritage project, which takes a heritage-based approach to IT museums in France and around the world. The unprecedented study of this heritage leads us to understand how to perpetuate and mediate contemporary scientific and technical knowledge, of which data is the new heritage. They also constitute the new corpora, which means that terminology work needs to be rethought. The ITinHeritage project aims to develop an innovative approach to digital humanities by creating a corpus from the collections of IT museums, organised in the form of a knowledge graph, and by using methods and tools that combine traditional linguistic approaches and explorations in the computer sciences. Big data, AI and NLP are thus being used to explore, enhance and perpetuate their own heritage
Caractérisation locale de matériaux en espace libre à l’aide du phénomène de jet électromagnétique
No full textInternational audienceDans cet article, nous présentons une étude portant sur l’exploitation du jet électromagnétique (EM) fonctionnant à 30 GHz afin de caractériser localement les matériaux. Nous exposons dans un premier temps les caractéristiques du jet EM, notamment l’intensité élevée générée au point focal (en champ proche) et la très faible largeur à mi-hauteur du faisceau ainsi que la quasi-planéité des fronts d’ondes. Une mesure du coefficient de réflexion via le jet EM a été réalisée sur un substrat FR4 Epoxy contenant des parties nues et métallisées de largeur 1, 2 et 3 cm. Les résultats expérimentaux obtenus sont favorablement comparés à ce qui avait été calculé analytiquement. Cela révèle une capacité du jet à mesurer la réponse électromagnétique locale de matériaux, dans le contexte de l’approximation de l’onde plane, avec une dimension pouvant atteindre jusqu’environ 1 cm. Enfin, une expérience a été menée afin de calculer la permittivité, révélant un écart de 5% par rapport à la valeur exacte
Local Control and Mixed Dimensions: Exploring High-Temperature Superconductivity in Optical Lattices
No full textInternational audienceThe simulation of high-temperature superconducting materials by implementing strongly correlated fermionic models in optical lattices is one of the major objectives in the field of analog quantum simulation. Here we show that local control and optical bilayer capabilities combined with spatially resolved measurements create a versatile toolbox to study fundamental properties of both nickelate and cuprate high-temperature superconductors. On the one hand, we present a scheme to implement a mixed-dimensional (mixD) bilayer model that has been proposed to capture the essential pairing physics of pressurized bilayer nickelates. This allows for the long-sought realization of a state with long-range superconducting order in current lattice quantum simulation machines. In particular, we show how coherent pairing correlations can be accessed in a partially particle-hole transformed and rotated basis. On the other hand, we demonstrate that control of local gates enables the observation of d -wave pairing order in the two-dimensional (single-layer) repulsive Fermi-Hubbard model through the simulation of a system with attractive interactions. Lastly, we introduce a scheme to measure momentum-resolved dopant densities, providing access to observables complementary to solid-state experiments—which is of particular interest for future studies of the enigmatic pseudogap phase appearing in cuprates. Published by the American Physical Society 202
