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Colloquium

Topic:

Why do things thermalize in a box?

Date:

26.04.21

Time:

16:15

Place:

cyberspace

Guest:

Masud Haque

Maynooth University, Ireland

Abstract:

The eigenstate thermalization hypothesis (ETH) is a cornerstone in our understanding of quantum statistical mechanics. In the first part of the talk, I will give a broad overview of thermalization of isolated quantum systems, and of the role played by random-matrix descriptions. The extent to which ETH holds for nonlocal operators (observables) is an open question. In the second half of the talk, I will address this question using an analogy with random matrix theory.

Contact person:

J. Schnack/FOR2692

Colloquium Mathematical Physics

Topic:

Integrability and Universality in nonlinear waves

Date:

05.02.21

Time:

16:15

Place:

ZOOM/Konferenzschaltung

Guest:

Tamara Grava

University of Bristol

Abstract:

What is an integrable system?  Intuitively, an integrable system is a dynamical system that can be integrated directly. While in principle integrable systems should be very rare, it happens that in nature, a lot of fundamental systems are  integrable such as many models of nonlinear waves, models in statistical mechanics and in theory of random matrices.  The study of nonlinear waves has led to many remarkable discoveries, one of them being 'solitons', found some 50 years ago. Solitons motivated the development of the Inverse Scattering Transform (IST). History and some examples will be discussed. Finally I will present some universality results about small dispersion limits and semiclassical limits of nonlinear dispersive waves.

Contact person:

G. Akemann

Seminar High Energy Physics

Topic:

Is Our Universe the Remnant of Chiral Anomaly in Inflation?

Date:

27.04.21

Time:

14:15

Place:

Online, via ZOOM

Guest:

Azadeh Maleknejad

CERN, Geneva

Abstract:

Modern cosmology has been remarkably successful in describing the Universe from a second after the Big Bang until today. However, its physics before that time is still much less certain. It profoundly involves particle theory beyond the Standard Model to explain long-standing puzzles: the origin of the observed matter asymmetry, nature of dark matter, massive neutrinos, and cosmic inflation. In this talk, I will explain that a new framework based on embedding axion-inflation in left-right symmetric gauge extensions of the SM can possibly solve and relate these seemingly unrelated mysteries of modern cosmology. The baryon asymmetry and dark matter today are remnants of a pure quantum effect (chiral anomaly) in inflation which is the source of CP violation in inflation. As a smoking gun, this setup has robust observable signatures for the GW background to be probed by future CMB missions and laser interferometer detectors.

Contact person:

D. Bödeker

Seminar Condensed Matter

Topic:

11:00 Uhr, Tumortherapie mit schweren Ionen

Date:

21.04.21

Time:

11:00

Place:

ZOOM / Konferenzschaltung

Guest:

Ann-Christin Sprenger

Universität Bielefeld

Abstract:

Contact person:

Jürgen Schnack

Seminar Mathematical Physics

Topic:

The Character Expansion in effective Theories for chiral Symmetry Breaking

Date:

03.12.20

Time:

16:30

Place:

ZOOM / Konferenzschaltung

Guest:

Noah Aygün

Universität Bielefeld

Abstract:

Contact person:

Gernot Akemann

Seminar Bielefeld-Melbourne Random Matrices

Topic:

Reflective intelligent surfaces: random matrices in 6G wireless systems modeling

Date:

21.04.21

Time:

09:00

Place:

ZOOM / Konferenzschaltung

Guest:

Giuseppa Alfano

CNR IEIIT, WCS Group, Turin

Abstract:

Radio channel modeling and system performance analysis for wireless  communications exploit random matrix theory since the very introduction of the multi-antenna transmission paradigm in late '90's.  Matrices from polynomial ensembles have been providing realistic and analytically handy models for communications taking place at frequencies typical of the third and fourth generation of mobile telephony, and still serve to analyze low-frequency performance in the most recent and currently developing fifth generation. The shift to far-higher frequencies planned for fifth and, especially,  sixth generation of mobile communications is leading to the adoption of radio channel models putting emphasis on geometry-related rather than on scattering-related information. In this scenario, both Euclidean as well as random Vandermonde matrices play a major role. The talk focuses on a representative case of 6G multi-antenna link, where signal transmission from transmit to receive uniform linear array is aided by a so-called "reflective intelligent surface", a passive device with signal-bearing capabilities only. This involves the analysis of products of random Vandermonde matrices with complex entries of unit modulus, with either random or deterministic matrices interspersed.

Contact person:

Gernot Akemann



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