Institut für Theoretische Physik
Start / Aktuell / Institut
November  2014
Mo
24.11.2014
Seminarraum A.04.101
Theoretische Physik
14:15
Quantenfeldtheorie (Forschungsseminar M.Phy.412)

Simone Dresti
Göttingen

An overview of Renormalization in Curved Space-Time



Kontakt: K.-H. Rehren
Mo
24.11.2014
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

Fabian Biebl
Universität Göttingen

Thermalization rates in a closed 1d quantum system



Kontakt: S. Kehrein
Di
25.11.2014
Seminarraum A3.101
Theoretische Physik
14:15
Theoretisch-physikalisches Seminar

Herbert Spohn
TU München

Equilibrium time correlations for anharmonic chains

Since the 1970ies it has been recognized that one-dimensional systems generically have anomalous transport. One manifestation is to consider the super-diffusive spreading of sound and heat peak for the time correlations of the conserved quantities in equilibrium. Recently I proposed a nonlinear extension of fluctuating hydrodynamics to capture the large scale behavior of the correlations. In my talk I will explain the basic theoretical construction and compare with molecular dynamics simulations. The theory amounts to a multi-component extension of the one-dimensional KPZ equation.

Kontakt: J. Oberreuter

Dezember  2014
Mo
01.12.2014
Sitzungszimmer Mathematik
Theoretische Physik
14:15
Born-Hilbert-Seminar

Jan Philip Solovej
University of Copenhagen

TBA



Kontakt: K.-H. Rehren
Mo
01.12.2014
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

Manuel Kreye
Universität Göttingen

TBA



Kontakt: S. Kehrein
Di
02.12.2014
SR 3, Institut für Theoretische Physik, A03.101
SFB 937
17:15
Seminar

Yael Roichman
University of Tel Aviv

Dynamics in Steady State in-Vitro Acto-Myosin Networks

We show that complex fluids such as actin networks respond to deformations differently at intermediate length scales than they do as a bulk material, at large distances. When characterizing passive entangled F-actin networks we found that this intermediate response regime, characterized by an decay with distance, persists to surprisingly large distances of 2-6 µm, which is comparable the size of a cell, and over ten times larger than the mesh size of the actin network. A similar cross-over was observed previously in microtubule networks at r_c = 15 µm, if not as clearly, and without explanation. We use this newfound understanding to extract structural information of active in-vitro reconstituted cytoskeleton networks, in which such analysis can be done in a controlled fashion.

Kontakt: Glormann
Mo
08.12.2014
Seminarraum A.04.101
Theoretische Physik
14:15
Quantenfeldtheorie (Forschungsseminar M.Phy.412)

Federico Dradi
Göttingen

TBA



Kontakt: K.-H. Rehren
Mo
08.12.2014
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

Debanjan Basu
Universität Göttingen

TBA

TBA

Kontakt: S. Kehrein
Mo
15.12.2014
SR4 oder Sitzungszimmer Mathematik
Theoretische Physik
14:15
Born-Hilbert-Seminar

Rainer Verch
Leipzig

TBA



Kontakt: K.-H. Rehren
Mo
15.12.2014
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

Benjamin Lenz
Universität Göttingen

TBA

TBA

Kontakt: S. Kehrein
Di
16.12.2014
Seminarraum A3.101
Theoretische Physik
14:15
Theoretisch-physikalisches Seminar

Markus Heyl
Universität Innsbruck

Many-body localization and quantum ergodicity in disordered long-range Ising model

Ergodicity in quantum many-body systems is —despite its fundamental importance — still an open problem. Many-body localization provides a general framework for quantum ergodicity, and may therefore offer important insights. In this talk, it will be shown using both numerical and analytical methods that long-range interacting Ising models with transverse-field disorder enter a many-body localized phase at infinite temperature, irrespective of the disorder strength. As a consequence, these systems are nonergodic. To characterize and quantify quantum ergodicity, a measure for distances in Hilbert space will be introduced. It will be shown that in spin-1/2 systems it is equivalent to a simple local observable in real space, which can be measured in current experiments of superconducting qubits, polar molecules, Rydberg atoms, and trapped ions.

Kontakt: S. Kehrein

Januar  2015
Mo
05.01.2015
Seminarraum A.04.101
Theoretische Physik
14:15
Quantenfeldtheorie (Forschungsseminar M.Phy.412)

Robert Czechowski
Göttingen

TBA



Kontakt: K.-H. Rehren
Do
08.01.2015
Sitzungssaal Mathematik
Theoretische Physik
15:15

Defects in two-dimensional quantum field theories are lines across which fields of the theory may have discontinuities. Such defects are called "topological" if their precise location does not matter when evaluating correlators. Topological defects contain a lot of information about the field theory in question. In this talk I will concentrate on two-dimensional topological and conformal field theories, and I would like to explain how two superficially quite different constructions turn out to be closely related when formulated via defects. These are 1) the orbifolding procedure, and 2) building field theories on surfaces with spin structure.

Kontakt: K.-H. Rehren
Mo
12.01.2015
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

David Storch
Universität Göttingen

TBA

TBA

Kontakt: S. Kehrein
Mo
19.01.2015
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

Ingo Homrighausen
Universität Göttingen

TBA

TBA

Kontakt: S. Kehrein
Di
20.01.2015
Seminarraum A3.101
Theoretische Physik
14:15
Theoretisch-physikalisches Seminar

Robin Steinigeweg
Technical University of Braunschweig

Real-time relaxation of currents in spin-1/2 chains: Progress by quantum typicality

We use the concept of typicality to study the real-time dynamics of spin and energy currents in spin-1/2 models in one dimension and at nonzero temperatures [1,2]. These chains are the integrable XXZ chain and a nonintegrable modification due to the presence of a staggered magnetic field oriented in z direction. In the framework of linear response theory, we numerically calculate autocorrelation functions by propagating a single pure state, drawn at random as a typical representative of the full statistical ensemble. By comparing to small-system data from exact diagonalization (ED) and existing short-time data from time-dependent density matrix renormalization group (tDMRG), we show that typicality is satisfied in finite systems over a wide range of temperature and is fulfilled in both, integrable and nonintegrable systems. For the integrable case [1], we calculate the long-time dynamics of the spin current and extract the spin Drude weight for large systems outside the range of ED. We particularly provide strong evidence that the high-temperature Drude weight vanishes at the isotropic point. For the nonintegrable case [2], we obtain the full relaxation curve of the energy current and determine the heat conductivity as a function of magnetic field, exchange anisotropy, and temperature.

Mo
26.01.2015
Seminarraum A3.101
Theoretische Physik
14:15
Aktuelle Probleme der theoretischen Festkörperphysik (Forschungsseminar M.Phy.411)

Davide Fioretto
Universität Göttingen

TBA

TBA

Kontakt: S. Kehrein
Do
29.01.2015
Sitzungssaal Mathematik
Theoretische Physik
15:15

The cobordism hypothesis classifies fully local topological field theories. It is an open problem to realize quantum Chern-Simons theory as a fully local field theory in this sense. I show how classical Chern-Simons theory and its "pre-quantization" (in the sense of geometric quantization) has a fully local incarnation, and how it implies the need to cancel the quantum anomaly by means of "p1-structure" (Atiyah 2-framings). I close with an outlook on how this could be used to get the fully local quantum theory.

Kontakt: K.-H. Rehren

Februar  2015
Mo
23.02.2015
SR4 oder Sitzungszimmer Mathematik
Theoretische Physik
14:15
Born-Hilbert-Seminar

Jakob Yngvason
Wien

TBA



Kontakt: K.-H. Rehren

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