I will discuss the resonance counting function for Schrodinger operators with compactly-supported, $L^\infty$, real-, or complex-valued potentials, in odd dimensions $d \geq 3$. In joint work with T. Christiansen, we prove that the set of such potentials for which the resonance counting function has maximal order of growth $d$ is generic.
Georgia Institute of Technology and Institut Universitaire de France
Time:
Wednesday, May 4, 2005 - 4:00pm
Location:
MSTB 254
Dissipative transport in solids can be described by a Markov
semigroup of completely positive operators on the observable algebra of the charge carriers creation and annihilation operators. A model of generators of such semigroups, called the quantum jump model, will be presented. The linear response theory will be shown to provide the expression of transport coefficients through a Green-Kubo formula. This formula will be justified rigorously through the spectral property of the
generator of the quantum jump model in various situations. The case of aperiodic solids, such as strongly disordered systems will be emphasized, in view of its relevance in the theory of the Quantum Hall effect.
Indiana University-Purdue University in Indianapolis
Time:
Thursday, May 12, 2005 - 2:00pm
Location:
MSTB 254
Probability of a gap in the spectrum of a matrix from the
Gaussian Unitary Ensemble is given by a Fredholm determinant. Its asymptotics when the gap becomes large is an interesting problem related to Painleve equations, random permutations, etc. These asymptotics for the gap in the bulk of the spectrum were conjectured by Dyson. The proof was given over the years by Widom, Deift, Its , Zhou, and the speaker. In particular, the proof of the multiplicative constant in the asymptotics
was the last difficulty recently resolved. I will explain the method of determining this constant and the rest of the asymptotics (applicable also to other important Fredholm, and also Hankel, and Toeplitz determinants where the corresponding constant is not yet determined). The method uses the Riemann-Hilbert approach. This part of the talk will be based on the works of Deift, Its, Zhou, and the speaker.
I will describe our recent proof of localization at the bottom of the spectrum for Schrodinger operators with Poisson random potentials. Poisson random potentials are the most natural model for describing a material with impurities. This has been a longstanding open problem. I will give a very informal talk on work in progress.