Thema:

tba

Datum:

01.02.21

Uhrzeit:

16:15

Ort:

cyberspace

Vortragender:

JProf. Francesca Cuteri

Goethe-Universität Frankfurt

Inhalt:

Ansprechpartner:

F. Karsch/TR211

Thema:

The problem of latency in estimating the Covid-19 replication number

Datum:

08.05.20

Uhrzeit:

16:15

Ort:

ZOOM/Konferenzschaltung

Vortragender:

Lorenzo Sadun

University of Texas at Austin

Inhalt:

Figuring out how to restart the world's economy without a resurgence of disease depends on understanding how contagious Covid-19 really is. However, estimates of the basic replication number $R_0$ vary greatly, with well-respected groups publishing estimates whose 95% confidence intervals don't even overlap. In this talk I'll go over the basic SIR and SEIR models of disease spread and present several different ways to treat the latency period between being exposed and becoming infectious. Simple SEIR models are unstable; working with a fixed set of data, small changes to the model can result in large changes to the estimated value of $R_0$. More realistic models are more complicated and are even less stable. The upshot is that we know much less about $R_0$ than is generally believed, and the error bars on the high side are particularly large. Containing the outbreak for an extended period may be a lot harder than our leaders think.

Ansprechpartner:

Gähler, Dr. Franz

Thema:

Quantum computing quantum field theory problems

Datum:

15.12.20

Uhrzeit:

14:15

Ort:

cyberspace

Vortragender:

Niklas Mueller

BNL

Inhalt:

I will present an overview over the exciting field of quantum computation from a high energy / nuclear theory perspective (No hardware, sorry!). After a brief but pedagogical introduction into the basic concepts, and into some of the interesting physics problems, I will try to explain what “quantum computing” a (lattice) field theory problem actually requires one to do: from digitizing the Hilbert space of ones favorite theory to coming up with an algorithm including preparing states and extracting information by measurement. As an example, I will mostly focus on quantum computation of a dynamical problem (scattering) in scalar phi^4 theory, and will be contrasting the current state-of-the-art approach by Jordan, Lee and Preskill with one we are currently developing. I might talk about quantum computation/simulation of gauge theories, if time permits.

Ansprechpartner:

S. Schlichting

Thema:

Evaluation der Genauigkeit des Tschebyscheff-Algorithmus zur Bestimmung thermodynamischer Funktionen am Beispiel einer Heisenberg-Spin-Leiter

Datum:

11.09.20

Uhrzeit:

14:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Henrik Schlüter

Universität Bielefeld

Inhalt:

Es wird eine Einführung in die numerische Berechnung thermodynamischer Funktionen mithilfe des Tschebyscheff-Algorithmus gegeben. Anschließend findet eine Bewertung der Ergebnisse am Beispiel einer Heisenberg-Spin-Leiter in Abhängigkeit der Tschebyscheff-Parameter statt.

Ansprechpartner:

Jürgen Schnack

Thema:

Statistics of Extremes in Eigenvalue-counting Staircases

Datum:

04.06.20

Uhrzeit:

16:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Yan Fyodorov

King's College London

Inhalt:

We consider the counting function (“spectral staircase”) for eigenvalues of a random unitary matrix, drawn from the corresponding beta-ensemble. Our goal is to characterize the statistics of maximum deviation of this staircase from its mean slope in a fixed interval, when size of the matrix N >>1. We will show that one-sided extremes can be addressed by exploiting a mapping onto the statistical mechanics of log-correlated random processes and using an extended Fisher-Hartwig conjecture. The resulting statistics exhibits combined features of counting statistics of Fermions with Sutherland-type interaction and extremal statistics of the fractional Brownian motion with Hurst index H = 0. Some of the features are expected to be universal. The talk is based on the paper Fyodorov-Le Doussal arXiv:2001.04135.

Ansprechpartner:

Gernot Akemann

Thema:

Dip-ramp-plateau and some random matrix inter-relations

Datum:

30.09.20

Uhrzeit:

09:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Peter Forrester

University of Melbourn

Inhalt:

Dip-ramp-plateau refers to the graphical shape of the average of the quadratic statistic  |?_{j=1}^N e^{i k ?_j}|^2 , which in turn is closely related to the spectral form factor. This has received prominence in recent studies of the SYK model and many body quantum chaos. For the GUE, a result of Brézin and Hikami from 1997 gives an identity relating this to the cumulative distribution of the density of the LUE with Laguerre parameter a=0. A derivation will be given, due to Okuyama, which can be generalised to show that for the LUE this statistic can be expressed in terms of the cumulative distribution of the density of the JUE with parameter b=0. Some scaling limits will be discussed.

Ansprechpartner:

Anas Rahman