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Aktuelle Veranstaltungen

 

Kolloquium

Thema:

Used Nuclear Fuel - Past, Present, and Future

Datum:

29.01.18

Uhrzeit:

16:15

Ort:

H6

Vortragender:

Dr. Maik Stuke

Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH

Inhalt:

After a short introduction and overview of the company GRS I will focus on the past, present, and future of nuclear fuel used in German nuclear reactors. A summary of the origin and composition of different types of used nuclear fuel will be followed by an overview of the current situation and future plans of storage. This includes an overview of the foreseen steps until a final repository. I summarize my talk by discussing some open scientific questions.

Ansprechpartner:

D. Schwarz

Kolloquium Mathematische Physik

Thema:

Mesoscopic eigenvalue correlations of random matrices

Datum:

01.12.17

Uhrzeit:

16:00

Ort:

V2-210/216

Vortragender:

Antti Knowles

University of Geneva

Inhalt:

Ever since the pioneering works of Wigner, Gaudin, Dyson, and Mehta, the correlations of eigenvalues of large random matrices on short scales have been a central topic in random matrix theory. On the microscopic spectral scale, comparable with the typical eigenvalue spacing, these correlations are now well understood for Wigner matrices thanks to the recent solution of the Wigner-Gaudin-Dyson-Mehta universality conjecture. In this talk I focus on eigenvalue density-density correlations between eigenvalues whose separation is much larger than the microscopic spectral scale; here the correlations are much weaker than on the microscopic scale. I discuss to what extent the Wigner-Gaudin-Dyson-Mehta universality remains valid on such larger scales, for Wigner matrices and random band matrices.

Ansprechpartner:

G. Akemann

Seminar Hochenergiephysik

Thema:

Improved real-time dynamics of thermal fields from lattice simulations

Datum:

18.01.18

Uhrzeit:

14:15

Ort:

D6-135

Vortragender:

Alexander Rothkopf

Heidelberg

Inhalt:

The determination of real-time information from lattice simulations at finite temperature is a central challenge in our quest to nonperturba-tively connect first principles theory to experimental measurements. In the context of relativistic heavy-ion collisions, the shear viscosity of the quark-gluon plasma is one pertinent example, which with standard simulation methods is exponentially hard to obtain. In this talk I will discuss the challenges of computing real-time quantities via the extraction of spectral functions from standard lattice simulations and introduce a recent proposal of how to possibly circumvent these. In it, thermal fields are simulated on a lattice in a non-compact imaginary time, which allows one to resolve correlation functions in between the conventional Matsubara frequencies. Results from a (0+1)d proof-of-principles simulation are presented, which show that a significant improvement in the reconstruction of spectral features may be achieved. [1] J.M. Pawlowski, A.R. arXiv:1610.09531

Ansprechpartner:

O. Kaczmarek

Seminar Kondensierte Materie

Thema:

Finite-temperature dynamics using matrix product states

Datum:

26.01.18

Uhrzeit:

14:15

Ort:

V2-205

Vortragender:

Salvatore Manmanna

Universität Göttingen

Inhalt:

Ansprechpartner:

Jürgen Schnack

Seminar Mathematische Physik

Thema:

Exploring the boundaries of universality for Gaussian perturbations of Hermitian matrices

Datum:

18.01.18

Uhrzeit:

16:00

Ort:

D5-153

Vortragender:

Thorsten Neuschel

University Catholique de Louvain

Inhalt:

We explore the boundaries of sine kernel universality for the eigen- values of Gaussian perturbations of large deterministic Hermitian ma- trices. Equivalently, we study for deterministic initial data the time after which Dyson's Brownian motion exhibits sine kernel correlations. We explicitly describe this time span in terms of the limiting density and rigidity of the initial points. This is joint work with Tom Claeys and Martin Venker.

Ansprechpartner:

Gernot Akemann

Seminar AG Zufallsmatrizen

Thema:

Local inhomogeneous circular law

Datum:

18.12.17

Uhrzeit:

14:15

Ort:

V3-201

Vortragender:

Johannes Alt

Institute of Science and Technology, Austria

Inhalt:

The density of eigenvalues of large random matrices typically converges to a deterministic limit as the dimension of the matrix tends to infinity. In the Hermitian case, the best known examples are the Wigner semicircle law for Wigner ensembles and the Marchenko-Pastur law for sample covariance matrices. In the non-Hermitian case, the most prominent result is Girko’s circular law: The eigenvalue distribution of a matrix X with centered, independent entries converges to a limiting density supported on a disk. Although inhomogeneous in general, the density is uniform for identical variances. In this special case, the local circular law by Bourgade et al. shows this convergence even locally on scales slightly above the typical eigenvalue spacing. In the general case, the density is obtained via solving a system of deterministic equations. In my talk, I explain how a detailed stability analysis of these equations yields the local inhomogeneous circular law in the bulk spectrum for a general variance profile of the entries of X. This result was obtained in joint work with László Erdos and Torben Krüger. 1

Ansprechpartner:

Friedrich Götze



  • @ 2008 Uni Bielefeld
  • | Letzte Änderung: 23.11.2011
  •  Olaf Kaczmarek
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