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Physique Théorique
(124) Production(s) de l'année 2018
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Spin Hall effect
Auteur(s): Dyakonov M.
Conférence invité: Fifty Years of Spin Physics (Paris, FR, 2018-06)
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Boundary constraints on population dynamics in a percolating habitat
Auteur(s): Munoz Francois, Huth G., Pitard E.
(Article) Publié:
Ecological Complexity, vol. 36 p.230-238 (2018)
Ref HAL: hal-02025664_v1
DOI: 10.1016/j.ecocom.2018.09.002
WoS: WOS:000455065400022
Exporter : BibTex | endNote
Résumé: The spatial distribution of suitable environmental conditions defines a species habitat, and colonization-extinction dynamics within this habitat determine the distribution of species populations. In addition, the success of colonization and the risk of extinction are expected to be influenced by the proximity to habitat boundary. We address here the influence of boundary vicinity for a contact-process model of population dynamics in a percolating habitat lattice. To separate the influence of boundary vicinity from that of fragment area, we investigate population dynamics in the very large spanning cluster of the percolating habitat. The geometry of the spanning cluster varies when habitat density in the lattice is tuned away from the percolation threshold. We expect that the colonization success decreases closer to the boundary, leading to depleted site occupancy in the cluster, and that this effect is even more pronounced near the extinction threshold of the contact process. For the set of suitable sites of the cluster and unsuitable sites next to its boundary, we quantify the boundary density, σ, as the probability to draw a pair of suitable and unsuitable sites. The cluster boundary is most rugged and σ is maximal close to the percolation threshold of the habitat. We expect that the global influence of boundary on population dynamics in the cluster is greater when the boundary is more rugged. We thus investigate population dynamics in the spanning cluster for varying values of σ. We determine the stationary properties of population dynamics in the spanning cluster according to σ and to the species-specific ratio of extinction and colonization rates, denoted r. Using both numerical simulations and a pair-approximation model, we assess global species persistence and site occupancy patterns in the spanning cluster. We show that the extinction threshold rc depends crucially on σ, i.e., increasing σ limits global species persistence. Furthermore, increasing σ decreases the probability of site occupancy in the spanning cluster. A key result is that this influence extends to sites far from the boundary when r gets close to rc. Therefore, species that are at risk of extinction are more sensitive to the influence of habitat boundary. These results are of both theoretical and practical interest for understanding and forecasting species viability in heterogeneous and fragmented habitats.
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Strong light-matter coupling in a quantum metasurface
Auteur(s): Felbacq D., Rousseau E.
Conference: SPIE Nanoscience + Engineering (San Diego, US, 2018)
Actes de conférence: Proceedings of SPIE, vol. 10721 p.1072128 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-02019418_v1
DOI: 10.1117/12.2320277
WoS: WOS:000451765300010
Exporter : BibTex | endNote
Résumé: Metasurfaces have been used for light manipulation and control, from the point of view of planar optics or polarization control, or non-linear light extraction. The properties of metasurfaces is rooted in the presence of resonant basic elements which are responsible for strongly confined electromagnetic surface modes. We propose to use these modes to enhance light-matter interaction in the vicinity of the surface by considering hybrid structure made of a thin layer, such as a 2D quantum material or a thin film with embedded quantum dots. A semi-classical theory will be proposed along with some functionalities attainable with the device.
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On the asymptotic variance of the number of real roots of random polynomial systems
Auteur(s): Armentano D., Azaïs Jean-Marc, Dalmao F., Léon J.
(Article) Publié:
Proceedings Of The American Mathematical Society, vol. 146 p.5437-5449 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01980703_v1
DOI: 10.1090/proc/14215
WoS: 000447836000039
Exporter : BibTex | endNote
4 Citations
Résumé: We obtain the asymptotic variance, as the degree goes to infinity, of the normalized number of real roots of a square Kostlan-Shub-Smale random polynomial system of any size. Our main tools are the Kac-Rice formula for the second factorial moment of the number of roots and a Hermite expansion of this random variable.
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Stretched and compressed exponentials in the relaxation dynamics of a metallic glass- forming melt
Auteur(s): Wu Zhen wei, Kob W., Wang Wei-hua, Xu Limei
(Article) Publié:
Nature Communications, vol. 9 p.5334 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01981718_v1
DOI: 10.1038/s41467-018-07759-w
WoS: WOS:000453441300002
Exporter : BibTex | endNote
14 Citations
Résumé: The dynamics of glass-forming systems shows a multitude of features that are absent innormal liquids, such as non-exponential relaxation and a strong temperature-dependence ofthe relaxation time. Connecting these dynamic properties to the microscopic structure of thesystem is challenging because of the presence of the structural disorder. Here we usecomputer simulations of a metallic glass-former to establish such a connection. By probingthe temperature and wave-vector dependence of the intermediate scattering function wefindthat the relaxation dynamics of the glassy melt is directly related to the local arrangement oficosahedral structures: Isolated icosahedra give rise to a liquid-like stretched exponentialrelaxation whereas clusters of icosahedra lead to a compressed exponential relaxation that isreminiscent to the one found in a solid. Our results show that in metallic glass-formers thesetwo types of relaxation processes can coexist and give rise to a dynamics that is surprisinglycomple
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InAs/InP quantum dot-nanowire single photon sources in the telecom band grown monolithically on silicon substrates
Auteur(s): Jaffal Ali, Redjem W., Regreny Philippe, Nguyen Hai-Son, Cueff Sébastien, Letartre Xavier, Patriarche Gilles, Rousseau E., Cassabois G., Gendry Michel, Chauvin Nicolas
Conference: C'Nano (Toulon, FR, 2018-12-11)
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Structuring and degrading polymer gels via catalytic reactions
Auteur(s): Hugouvieux Virginie, Kob W.
Conférence invité: Réunion plénière du GDR SLAMM (Solliciter LA Matière Molle) (Hyères, FR, 2018-11-12)
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