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Many-body enhancement of energy storage in a waveguide-QED quantum battery
No full textInternational audienceQuantum batteries have demonstrated remarkable charging properties, showing that a quantum advantage is possible in the realm of quantum thermodynamics. However, finding an effective strategy to store energy for long periods remains crucial in these systems. Here, we investigate different configurations of a waveguide-QED system acting as a quantum battery and show that, in this context, collective effects can slow down the self-discharging time of the battery, thus improving the storage time. Specifically, when the artificial atoms of the array are arranged randomly, the energy and ergotropy of the optical system are shown to decay at a subexponential rate over long periods, in contrast to the energy decay of a single atom in a waveguide. In the case of atoms arranged in an ordered lattice, collective effects slow down dissipative discharging only for a specific lattice spacing. Thus, in both configurations, collective effects can be used to boost the energy-protection properties of optical systems
Adapting coherent-state superpositions in noisy channels
No full textInternational audienceQuantum non-Gaussian states are crucial for the fundamental understanding of non-linear bosonic systems and simultaneously advanced applications in quantum technologies. In many bosonic experiments the important quantum non-Gaussian feature is the negativity of the Wigner function, a cornerstone for quantum computation with bosons. Unfortunately, the negativities present in complex quantum states are extremely vulnerable to the effects of decoherence, such as energy loss, noise and dephasing, caused by the coupling to the environment, which is an unavoidable part of any experimental implementation. An efficient way to mitigate its effects is by adapting quantum states into more resilient forms. We propose an optimal protection of superpositions of coherent states against a sequence of asymmetric thermal lossy channels by suitable squeezing operations
The Roman She-Wolf in 8th-century Ustrushana (Northern Tajikistan): cross-craft interactions in theatrical representations between ancient Rome and China
No full textInternational audienceThe image of the Roman she-wolf suckling the abandoned twins Romulus andRemus continues to provoke scholarly debate—not only regarding the possibleEtruscan origins of the legend and its iconography, but also in relation to itsreception across diverse media and its diffusion far beyond the borders of theRoman and Byzantine empires. The discovery of a wall painting (2nd half 8thcentury) depicting a she-wolf nursing two infants in the royal palace of the cityof Shahristan, capital of the kingdom of Ustrushana, in present-day northernTajikistan, remains one of the most remarkable surprises in Central Asiaticarchaeology. Boris Marshak in 1981, then recently Frantz Grenet, proposed atheatrical intermediary as a possible channel for the transmission of this legendfrom the Mediterranean world to Transoxiana. In this paper, Anca Dan addsevidence for the diffusion of this symbol through cross-crafting practices inRoman and Sogdian contexts. The study traces both the narrative’s spread inRoman and Byzantine texts and the transmission of its iconography—on coins,bracteates, and architectural decorations (such as paintings)—from Rome andConstantinople to the fringes of the Tang Empire, on the eve of the Muslimconquest
Emmanuel Terray en sa cité anthropologique (II) : lire et militer entre l’Allemagne et la France
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: Entretiens contre la disparition
No full textInternational audienceLe 10 février 2023, Janargul Jumatay, journaliste d’origine kazakhe, est arrêtée au domicile de sa sœur dans le village de Biyangu, situé dans les montagnes près d’Ürümchi, la capitale de la Région autonome ouïghoure du Xinjiang, appelée aussi « Région ouïghoure » ou « Turkestan oriental » par les membres de la diaspora. Elle a témoigné par téléphone le 29 décembre 2022 dans une longue interview avec le défenseur des droits humains Serikjan Bilash de l’organisation Ata Jurt basée à Almaty, et la conversation a été rendue publique avec son consentement sur YouTube. Durant cette discussion, elle expose en détail les conditions de vie extrêmement difficiles qu’elle subit après avoir été détenue dans un camp de rééducation pendant près de deux ans. Afin de faciliter la lecture de cet entretien, mené en kazakh, quelques coupes et réagencements de textes ont été faits, des titres et intertitres tirés des paroles de Janargul Jumatay ont été proposés, et quelques informations supplémentaires ont été incluses. Toutes les modifications sont clairement indiquées
The Synopsis of the Holy Scripture falsely attributed to John Chrysostom and the Bible in use at Antioch
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Les Lieux saints de Jérusalem : concurrence, partage et procédures d’arbitrage. L’exemple du Calvaire à la fin de la période mamelouke
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Morphogenesis: Pressure from within shapes the egg
No full textInternational audienceA new study explores the role of mechanical pressure in regulating morphogenesis during Drosophilaoogenesis. Actomyosin contractility is mechanically patterned in space and time in somatic cells by thegrowth of the underlying germline cells via a process involving the activation of the calcium channel TRPM
Holocene climate dynamics in the central Mediterranean inferred from pollen data
No full textInternational audienceThe Mediterranean climate is characterised by strong seasonality, which is critical for the ecosystems and societies in the region and makes them susceptible to climate change. The timing of when the Mediterranean climate developed over the past few thousand years remains a complex and unresolved question. Most studies document a part of the Mediterranean area or are based on a single (and frequently different) climate reconstruction method, which can lead to non-negligible biases when considering climate changes on a Mediterranean scale. Several climate summaries based on pollen data have recently been produced on a European scale. However, few of them have focused exclusively on the Mediterranean area, except for two recent syntheses documenting the eastern and western parts of the Mediterranean basin. We aimed to document the climate changes in the central Mediterranean during the Holocene, including trends and different patterns. A robust methodology has been applied to 38 pollen records spreading across the south of France and Italy. Four climate reconstruction methods based on different mathematical and ecological concepts have been tested (MAT, WA-PLS, BRT and RF), and the selection of the best modern calibration dataset has also been investigated to produce the most reliable results. Particular attention has been paid to the seasonal nature of climatic parameters (winter and summer temperatures and precipitation). A model-data comparison has been made using the transient model simulation TraCE-21ka in an attempt to gain a better understanding of the climate mechanisms and their forcing. Our palaeoclimate reconstruction shows that during the mid Holocene, summer temperatures were slightly colder than modern-day conditions in the southern part of the central Mediterranean region, which is not completely in accordance with the summer temperature reconstructions of the Iberian Peninsula and eastern Mediterranean for the mid Holocene. In northern parts of the central Mediterranean region, and particularly in high elevation (> 1000 m), a Holocene thermal maximum is present, contrasting with the cold summer temperature anomalies previously reconstructed with pollen data for the Mediterranean region. Holocene summer conditions were characterised by specific spatio-temporal patterns, i.e., a west–east differentiation in southern France and a north–south one in Italy, for both temperature and precipitation. Holocene winter conditions showed a more homogeneous spatio-temporal pattern, i.e., general humidification and warming throughout the Holocene for Italy and southern France, which is coherent with the winter temperature reconstructions of the Iberian Peninsula and eastern Mediterranean. A data–model comparison shows a mostly coherent signal in winter but an incoherent one in summer. Those discrepancies between model simulations and pollen-based reconstructions suggest that during the Holocene, the northern Mediterranean climate was already subject to a marked spatio-temporal variability, particularly in summer, that cannot only be explained by changes in orbital configuration and atmospheric greenhouse gas evolution. Finally, our result highlighted the onset of the “Mediterraneanization” of the central Mediterranean region, characterised by wet winters and dry summers, after 8000 years Before Present (BP). The “Mediterraneanization” process seems to have had a greater impact on the southern regions than on the northern regions