Nonlinear Quantum Graphs

Liste des Contributions

12. On the existence of prescribed L^2 norm solutions for nonlinear Schrödinger equations on metric graphs: the mass supercritical case

louis Jeanjean (Université de Franche-Comté)

11/01/2024 13:30

In this talk we discuss the existence of prescribed L^2 norm solutions to nonlinear Schrödinger equations set on metric graphs. A common strategy employed to find such a solution is to search for a constrained critical point of the associated energy functional. Some geometric properties of the functional vary depending on the exponent in the nonlinear term of the equation. In the so-called...

13. Existence of infinitely many normalized solutions for mass-supercritical nonlinear Schrödinger equations on noncompact metric graph.

M. Pablo Carrillo (Université de Franche-Comté)

11/01/2024 14:20

This talk builds on the one of L. Jeanjean. In the mass-supercritical case we consider nonlinear Schrödinger equations on a noncompact metric graph with a localized nonlinearity. We show, for any prescribed L^2 norm, the existence of infinitely many solutions having this norm.
The usual procedure to obtain one solution is to prove that the associated energy functional possesses, on the...

15. Constant sign and sign changing NLS ground states on noncompact metric graphs

Colette De Coster

11/01/2024 15:45

We investigate existence and nonexistence of positive and nodal action ground states for the nonlinear Schrödinger equation on noncompact metric graphs with rather general boundary conditions. For noncompact graphs with finitely many edges, we detect purely topological sharp conditions preventing the existence of ground states or of nodal ground states. We also investigate analogous conditions...

16. Qualitative properties of solutions of NLS on metric graphs

Damien Galant (Université Polytechnique Hauts de France (CERAMATHS/DMATHS))

11/01/2024 16:35

In this talk, we will study qualitative properties of solutions to the Nonlinear Schrödinger Equation -u'' + au = |u|ᵖ⁻²u on compact metric graphs.
Among the questions of interest are:

• if the graph possesses a symmetry, what about its positive solutions? What about action ground states? Can one identify and describe symmetry-breaking situations depending on parameters (lengths of edges,...

18. GRAFIDI: une librairie Python pour faire des simulations sur les graphes quantiques

M. Romain Duboscq (Institut de Mathématiques de Toulouse)

12/01/2024 09:00

Dans cet exposé, je présenterai mes travaux en collaboration avec Christophe BESSE et Stefan LE COZ autour de la simulation numérique pour les graphes quantiques (nonlinéaires). En particulier, je parlerai de la librairie Python GRAFIDI qui permet de résoudre numériquement des problèmes tels que le calcul d'états stationnaires ou bien encore l'évolution d'une solution de l'équation de...

14. Propriété spectrale du Laplacien sur des graphes

Serge Nicaise (Université Polytechnique Hauts-de-France)

12/01/2024 09:50

La connaissance de certaines propriétés spectrales de l’opérateur de Laplace sur des graphes a de nombreuses conséquences, en particulier dans l’étude de la stabilité asymptotique des petites ondes stationnaires pour NLS sur les graphes. L'objectif principal de mon exposé sera de rappeler quelques anciens résultats sur des graphes finis et de présenter quelques nouveaux résultats pour des...

17. Some aspects of the multiscale finite element method

Prof. Alexei LOZINSKI (Laboratoire de mathématiques de Besançon, Université de Franche-Comté)

12/01/2024 11:05

We shall talk about computational methods for multiscale partial differential equations, and in particular the multiscale finite element method (MsFEM). This is a finite element type method that performs a Galerkin approximation of the PDE on a problem-dependent basis. We shall discuss two aspects of these methods based on our recent work with Rutger Biezemans, Claude Le Bris, and Frédéric...

19. Blow-up on a star-graph

Stefan Le Coz

12/01/2024 11:55

We construct a finite time blow-up solution to the mass-critical focusing nonlinear Schrödinger equation on a metric star graph.