Monogamy of entanglement between cones

International audienceA separable quantum state shared between parties $A$ and $B$ can be symmetrically extended to a quantum state shared between party $A$ and parties $B_1,\ldots ,B_k$ for every $k\in\mathbf{N}$. Quantum states that are not separable, i.e., entangled, do not have this property. This phenomenon is known as "monogamy of entanglement". We show that monogamy is not only a feature of quantum theory, but that it characterizes the minimal tensor product of general pairs of convex cones $\mathsf{C}_A$ and $\mathsf{C}_B$: The elements of the minimal tensor product $\mathsf{C}_A\otimes_{\min} \mathsf{C}_B$ are precisely the tensors that can be symmetrically extended to elements in the maximal tensor product $\mathsf{C}_A\otimes_{\max} \mathsf{C}^{\otimes_{\max} k}_B$ for every $k\in\mathbf{N}$. Equivalently, the minimal tensor product of two cones is the intersection of the nested sets of $k$-extendible tensors. It is a natural question when the minimal tensor product $\mathsf{C}_A\otimes_{\min} \mathsf{C}_B$ coincides with the set of $k$-extendible tensors for some finite $k$. We show that this is universally the case for every cone $\mathsf{C}_A$ if and only if $\mathsf{C}_B$ is a polyhedral cone with a base given by a product of simplices. Our proof makes use of a new characterization of products of simplices up to affine equivalence that we believe is of independent interest

Farm‐saved seed, royalty rates, and innovation in plant breeding

International audienceSeed innovation is one major factor for improving agricultural productivity. For some self‐pollinated varieties, such as wheat, farmers have the option to buy certified seed from seed dealers or to use their own farm‐saved seed. Historically, farmers could use farm‐saved seeds for free, which led to reduced incentives to innovate for private breeding companies. In recent decades, several countries have established different royalty systems for farm‐saved seeds to favor research investment. We developed a theoretical model to compare these different systems. We compared six stylized systems by analyzing their impact on incentives to innovate, as well as production efficiencies at both the seed and agricultural production levels. Our findings indicate that royalty systems allowing for a certain proportion of farm‐saved seeds result in improved welfare. The systems that lead to the highest total welfare levels are those in which the royalty level on farm‐saved seeds is regulated. This includes systems where the royalty is either directly defined by a regulator (as in the French or UK systems) or imposed to match the royalty level of the certified seeds (as in the Australian system). The Australian system performs better under high research costs. Conversely, under low research costs, the best system is either the French or the UK system, depending on the relative cost of producing farm‐saved seeds versus certified seeds. In conclusion, it is possible to design efficient royalty systems to create and produce innovation, in a context where farmers can self‐produce this innovation

Hard vs. soft commitments: Experimental evidence from a sample of French gamblers

International audiencePeople use commitment devices to formalize and facilitate their goals. Self-commitments are ubiquitous and may take different forms: soft, when the commitment can be broken at a low cost, or hard, when that cost is high. The effects of soft and hard commitments have usually been studied separately. We conduct an online experiment with 1527 individuals representative of a big gambling company's client population to study the comparative effects of hard and soft commitment devices in a risk taking game. Our results show that asking for a hard limit leads subjects to reduce their risk-taking even when the limit turns out to be non-binding, i.e., the commitment is ex-post soft. Hard commitments lead to slightly lower levels of risk taking

Turkey’s Walled Borders: A Multiscalar Approach

International audienceIn addition to the walls built by Bulgaria on the Turkish-Bulgarian border and by Greece on the Greek-Turkish one, Turkey itself launched the construction of a concrete wall on its border with Syria in 2015. Two years later, it continued this policy of enclosure with the construction of a wall on its border with Iran. While the fortification of borders is not a dynamic peculiar to Turkey, a multiscalar approach enables us to situate this fortification policy within Turkey's own regional space. Observing these two walls on different geographical scales allows us to understand the converging interests of the various players involved in this strategy of fortification. This also makes it possible to draw out discourses that are probably less visible, such as the European Union's support for the creation of these walls

Euclid preparation: Determining the weak lensing mass accuracy and precision for galaxy clusters

International audienceWe investigate the level of accuracy and precision of cluster weak-lensing (WL) masses measured with the \Euclid data processing pipeline. We use the DEMNUni-Cov $N$-body simulations to assess how well the WL mass probes the true halo mass, and, then, how well WL masses can be recovered in the presence of measurement uncertainties. We consider different halo mass density models, priors, and mass point estimates. WL mass differs from true mass due to, e.g., the intrinsic ellipticity of sources, correlated or uncorrelated matter and large-scale structure, halo triaxiality and orientation, and merging or irregular morphology. In an ideal scenario without observational or measurement errors, the maximum likelihood estimator is the most accurate, with WL masses biased low by $\langle b_M \rangle = -14.6 \pm 1.7 \, \%$ on average over the full range M_\text{200c} > 5 \times 10^{13} \, M_\odot and z < 1. Due to the stabilising effect of the prior, the biweight, mean, and median estimates are more precise. The scatter decreases with increasing mass and informative priors significantly reduce the scatter. Halo mass density profiles with a truncation provide better fits to the lensing signal, while the accuracy and precision are not significantly affected. We further investigate the impact of additional sources of systematic uncertainty on the WL mass, namely the impact of photometric redshift uncertainties and source selection, the expected performance of \Euclid cluster detection algorithms, and the presence of masks. Taken in isolation, we find that the largest effect is induced by non-conservative source selection. This effect can be mostly removed with a robust selection. As a final \Euclid-like test, we combine systematic effects in a realistic observational setting and find results similar to the ideal case, $\langle b_M \rangle = - 15.5 \pm 2.4 \, \%$, under a robust selection

Space-time first-order correlations of an open Bose-Hubbard model with incoherent pump and loss

30 pages, 15 figuresInternational audienceWe investigate the correlation properties in the steady state of driven-dissipative interacting bosonic systems in the quantum regime, as for example non-linear photonic cavities. Specifically, we consider the Bose-Hubbard model on a periodic chain and with spatially homogeneous one-body loss and pump within the Markovian approximation. The steady state corresponds to an infinite temperature state at finite chemical potential with diagonal spatial correlations. Nonetheless, we observe a nontrivial behaviour of the space-time two-point correlation function in the steady state, obtained by exact diagonalisation. In particular, we find that the decay width of the propagator is not only renormalised at increasing interactions, as it is the case of a single non-linear resonator, but also at increasing hopping strength. We then compute the full spectral function, finding that it contains both a dispersive free-particle like dispersion at low energy and a doublon branch at energy corresponding to the on-site interactions. We compare with the corresponding calculation for the ground state of a closed quantum system and show that the driven-dissipative nature - determining both the steady state and the dynamical evolution - changes the low-lying part of the spectrum, where noticeably, the dispersion is quadratic instead of linear at small wavevectors

Multifunctional Expectile Regression Estimation in Volterra Time Series: Application to Financial Risk Management

International audienceWe aim to analyze the dynamics of multiple financial assets with variable volatility. Instead of a standard analysis based on the Black–Scholes model, we proceed with the multidimensional Volterra model, which allows us to treat volatility as a stochastic process. Taking advantage of the long memory function of this type of model, we analyze the reproduced movements using recent algorithms in the field of functional data analysis (FDA). In fact, we develop, in particular, new risk tools based on the asymmetric least squares loss function. We build an estimator using the multifunctional kernel (MK) method and then establish its asymptotic properties. The multidimensionality of the Volterra process is explored through the dispersion component of the convergence rate, while the nonparametric path of the risk tool affects the bias component. An empirical analysis is conducted to demonstrate the ease of implementation of our proposed approach. Additionally, an application on real data is presented to compare the effectiveness of expectile-based measures with Value at Risk (VaR) in financial risk management for multiple assets

Negated actions are simulated within the primary motor cortex

International audienceControversy persists regarding the representation of linguistically negated actions, specifically concerning activation and inhibitory mechanisms in the motor system, and whether negated action sentences evoke an initial motor simulation of the action to be negated. We conducted two experiments probing corticospinal excitability (CSE) and short-interval intracortical inhibition (SICI) in the primary motor cortex at different latencies while reading affirmative and negative action sentences. In experiment one, twenty-six participants read action and non-action sentences in affirmative or negative forms. Using transcranial magnetic stimulation, we probed CSE in hand muscles at rest and at several latencies after verb presentation. We observed a greater CSE for action sentences compared to non-action sentences, regardless of verb form. In experiment two, nineteen participants read affirmative and negative action sentences. We measured CSE and SICI at short and long latencies after verb presentation. CSE was greater for affirmative and negative action sentences at both latencies compared to rest. SICI did not change at the short latency but increased at longer latencies, regardless of verb form. Negated action sentences showed the same motor excitability as affirmed action sentences with no additional inhibition at early latencies. These results lend support for the idea that actions to be negated are initially simulated within the motor system. Neural differences between affirmative and negative action sentences may occur outside the primary motor cortex

Une goutte de sang

Alm@e Linguae n°2 Un@ Editions / PUPPATraduction inédite du récit La gota de sangre (1911) de Emilia Pardo Bazán, premier récit policier long de l'histoire du genre en Espagn

Choix, Présentation et annotation de textes de consolation du premier XVIIe siècle ( Théophile de Viau, Tristan L'Hermite, Malherbe)

International audienceThe volume édits a collection of texts on consolation, classified by topic, period, or practices. My work involved selecting, editing, and presenting the practice of consolation for four lyric texts: Théophile de Viau, "Consolation à M. de L.," 1621; Tristan, "Consolation à Monsieur de Gournay sur la perte de deux de ses enfants," Epitaph-Tombeau 10, La Lyre, 1643; Malherbe, "Vers de Malherbe à madame la comtesse sur la mort de sa fille," [1599]Le volume propose d'éditer un ensemble de textes sur la consolation, classées par topique, période ou pratiques. Mon travail a consisté à choisir, éditer et présenter la pratique de la consolation pour 4 textes lyriques: Théophile de Viau, « Consolation à M. de L. », 1621, Tristan, « Consolation à Monsieur de Gournay sur la perte de deux de ses enfans », épitaphe-tombeau 10., La Lyre, 1643; Malherbe, "Vers de Malherbe à madame la comtesse sur la mort de sa fille", [1599]