Tel Aviv University Hello everyone, The next colloquium talk will be held on Monday, 5/12/2011, 12:15, Schreiber 006, Tel Aviv University. The speaker is Simone Warzel (Princeton and TU Munich) and the title of her talk is Resonances and absolutely continuous spectra of random operators on tree graphs The abstract is given below. Tea and coffee at 12:00, same room. Hope to see you there. For information about future colloqiua, see <http://www.math.tau.ac.il/~klartagb/colloq_2011.html> You are all welcome to suggest colloquium speakers, especially for the end of January and for the second semester. Yours, Bo'az -------------- Abstract: Motivated by the quest for a theory of quantum transport in disordered media, in 1958 P.W. Anderson came up with a model for a quantum particle in a random energy landscape. Among its interesting features is a conjectured sharp transition from a regime of localized eigenstates to one of diffusive transport. Until today it remains a mathematical challenge to establish these features in the framework of random Schroedinger operators. In this talk, I will describe recent progress in the understanding of the spectral and dynamical properties of such operators in case the underlying configuration space is a tree graph. Among the surprising phenomena which we discover is that even at weak disorder the regime of absolutely continuous states extends well beyond the one of the graph Laplacian. As will be explained in the lecture, the mathematical mechanism for the appearance of absolutely continuous states in this non-perturbative regime are disorder-induced resonances. --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: <klartagb@post.tau.ac.il>