Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Série LPTMS
Domaines physics
Date Mardi 18 Décembre 2018
Heure 11:00
Institut LPTMS
Salle LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay
Nom de l'orateur Texier
Prenom de l'orateur Christophe
Addresse email de l'orateur
Institution de l'orateur LPTMS, Université Paris-Sud
Titre Counting the equilibria of a directed polymer in a random medium and Anderson localisation
Résumé I will discuss a new connection between two different problems: the counting of equilibria of a directed polymer in a random medium (DPRM) and the problem of Anderson localisation for the 1D Schrödinger equation. Using the Kac-Rice formula, it is possible to express the mean number of equilibria of a DPRM in terms of functional determinants. In the one-dimensional situation, these functional determinants can be calculated thanks to the Gelfand-Yaglom method, showing that the mean number of equilibria of the DPRM growth exponentially with the length of the polymer, with a rate controlled by the generalized Lyapunov exponent (GLE) of the localisation problem (cumulant generating function of the log of the wave function). The GLE is solution of a spectral problem studied by combining numerical approaches and WKB-like approximation. Furthermore, the formalism can be extended in order to obtain the number of equilibria at fixed energy, providing the (annealed) distribution of the energy density of the line over the equilibria. Reference: Yan V. Fyodorov, Pierre Le Doussal, Alberto Rosso and Christophe Texier, Exponential number of equilibria and depinning threshold for a directed polymer in a random potential, Annals of Physics 397, 1-64 (2018)
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