Séminaires

Mark HOEFER (Penn State University)
Hydrodynamic Soliton Tunneling.
Jeudi 22 juin, 10h30.
Amphi du CERLA.

Quantum tunneling corresponds to the transmission of a particle with non-negligible probability through a barrier that a classical particle could not pass. This linear concept has been generalized to solitons -- localized, nonlinear waves -- incident upon an externally imposed barrier. The relevant questions are: can the soliton be transmitted, reflected, or trapped by the barrier? In this talk, the concept of hydrodynamic tunneling is introduced whereby solitons are incident upon nonlinear wavetrains of hydrodynamic origin including dispersive shock waves (DSWs) and rarefaction waves (RWs). The distinction from classical tunneling is that the barrier is not externally imposed, rather the propagation medium itself evolves and nonlinearly interacts with the soliton. The soliton transmission conditions are determined utilizing the mathematical tools of hydrodynamic theory (Riemann invariants) and nonlinear wave, Whitham modulation theory. The transmission condition, i.e., the transmitted soliton amplitude as a function of the incident soliton amplitude and flow conditions, correspond to a Riemann invariant of the degenerate modulation equations. The soliton trajectory corresponds to a characteristic of the modulation equations. Trapping and transmission of solitons through DSWs and RWs are shown to exhibit a reciprocity principle whereby solitons tunnel through both according to a reciprocal transmission condition. The theoretical formulation is general and is applied to the Korteweg-de Vries and Nonlinear Schr\"{o}dinger equations, models of a wide variety of fluid, optical, and condensed matter phenomena. Experiments in a nonlinear, dispersive fluid realizing soliton tunneling will also be presented.

Mini-cours de Pierre-Emmanuel Caprace
Réseaux exotiques. Réseaux irréductibles dans les produits de groupes simples.
Mercredi 1er mars, 13h30-15h, Vendredi 3 mars (séminaire de Geo-Dyn) et Lundi 6 mars, 13h30-15h.
Salle à préciser.

On s'intéresse aux groupes discrets qui apparaissent comme réseaux dans des groupes localement compacts non linéaires, mais qui jouissent néanmoins d'une propriété analogue aux réseaux de groupes de Lie simples de rang supérieur, à savoir l'absence de quotient propre infini. On s'intéressera en particulier aux propriétés résiduelles (résiduelle finitude, séparabilité des sous-groupes) de ces réseaux. Le plan des trois exposés successifs est le suivant; le premier dressera le paysage général, les deux suivants seront plutôt axés sur des exemples concrets.

Mini-cours de Carlangelo Liverani (Universitá di Roma II - Tor Vergata).
Functional analytic approach to hyperbolic dynamical systems.
Mercredi 8 Février 2016, 10h-12h.
Salle Kampé de Fériet, bâtiment M2

I will discuss the construction of anisotropic Banach spaces in order to establish statistical properties of hyperpolic dynamical systems.

Chushun TIAN (Institute of Advanced Study, Tsinghua University, Beijing, China).
Topology and Symmetries in the quantum kicked rotor 2.
Seminar of the "Atomes Froids" group and CEMPI
Vendredi 7 octobre 2016, 10h00.
PhLAM, salle 172, bâtiment P5 bis.

Maxim Olchanyi (Department of Physics, University of Massachusetts Boston)
The Inverse Linearization Problem.
Jeudi 9 juin 2016, 11h00.
Amphi Pierre Glorieux, CERLA.

We investigate the relationship between the nonlinear partial differential equations (PDEs) of mathematical physics and the their linearizations around stationary localized solutions. It turns out that for the PDEs of sine-Gordon type, it is possible to solve the Inverse Linearization Problem, i.e. given the linear stability analysis equations, to restore the original PDE. Of a particular interest are the instances of transparency of the former that may hint

Bruno Laburthe-Tolra (Laboratoire de Physique des Lasers Université Paris 13).
Dipolar Chromium Atoms: Spin Dynamics in Optical Lattices and Thermodynamics.
Résumé de l'exposé de Bruno Laburthe-Tolra.
Jeudi 19 novembre 2015, 11h00.
Salle 172, P5 bis.

CEMPI seminar day
Mardi 16 juin 2015.
Salle Kampe, M2.

Le programme  de la journée est :

  • D. Agafontsev (P.P. Shirshov Institute of Oceanology of RAS):"Integrable turbulence and formation of rogue waves"

  • D. Horoshko (B.I.Stepanov Institute of Physics, NASB, Minsk): Quantum superpositions of two-mode coherent states: creation, entropic measures and entanglement.

  • C. Mejia-Monasterio (Technical University of Madrid): From Hamilton to Boltzmann: The scattering road to equilibrium.

  • P.E. Parris (Missouri University of Science & Technology): Models versus Materials: How well do disorder based transport theories actually describe charge transport in real molecularly doped polymers?

Les résumés des exposés sont disponible sur la page http://math.univ-lille1.fr/~cempi/activites_scientifiques/FR/seminaires/files/CSD_resumes.php
Le programme détaillé de la journée est disponible sur la page http://math.univ-lille1.fr/~cempi/activites_scientifiques/FR/seminaires/files/CSD_prog_fr.php

Samuel Lellouch, Laboratoire Charles Fabry de l Institut d Optique (Palaiseau).
Propagation of Collective Pair Excitations in Disordered Bose Superfluids.
Vendredi 20 juin 2014, 11h00.
Salle 172 P5 bis.

Lev Khaykovich.
Universal few-body physics in ultracold atoms.
Résumé
Mardi 5 Mars 2013, 11h00.
Salle 172, P5 bis

Maxim Olchanyi.
Solitons.
Résumé
14 Novembre 2012, 14h00.
Salle de conférence du CERLA.