Dezember 2014  
Di 
23.12.2014
SR 3, Institut für Theoretische Physik, A03.101
SFB 937

17:15 
Seminar
Kontakt:
Glormann

Januar 2015  
Di 
06.01.2015
Seminarraum A3.101
Theoretische Physik

14:15 
Theoretischphysikalisches Seminar
Michael Brockmann Institute for Theoretical Physics, University of Amsterdam
Two quenches in integrable systems and their nonthermal steady states In this talk we study quench problems in two different interacting integrable theories. The first one is described by a quench protocol where the ground state of a free manyparticle bosonic theory in one dimension is let unitarily evolve in time under the integrable LiebLiniger Hamiltonian of δinteracting repulsive bosons. In the second one the antiferromagnetic ordered Néel state, the ground state of the spin1/2 Ising chain, is quenched to the anisotropic Heisenberg spin chain. By using a variational method, the socalled quench action method, we obtain the exact nonthermal steadystates of the systems in the thermodynamic limit, which correctly reproduce expectation values of local observables. Besides being rare cases of exact solutions to truly interacting quench situations, those two quench protocols represent examples where a naive implementation of the generalized Gibbs ensemble fails. Kontakt:
Stefan Kehrein

Mi 
07.01.2015
SR 3, Institut für Theoretische Physik, A03.101
SFB 937

14:15 
Kontakt:
Glormann

Do 
08.01.2015
Sitzungssaal Mathematik
Theoretische Physik

15:15 
Graduiertenkolleg 1493
Ingo Runkel Hamburg
Orbifolds and spin structures from defects in twodimensional field theories Defects in twodimensional 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 twodimensional 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 
12.01.2015
Sitzungszimmer Mathematik
Theoretische Physik

14:15 
BornHilbertSeminar
Detlev Buchholz Göttingen
Superpositions, Transition Probabilities and Primitive Observables Concepts, familiar from pure states in quantum mechanics, such as "superposition" and "transition probability", are shown to be also meaningful for generic states in infinite systems, described by funnels of type I_\infty algebras. In the physically important case of states of Connesvon Neumann type III_1, these concepts also have a physically significant operational interpretation in terms of primitive observables. (Joint work with Erling St\ormer.) Kontakt:
K.H. Rehren

Di 
13.01.2015
SR 3, Institut für Theoretische Physik, A03.101
SFB 937

17:15 
Seminar
Markus Maniak University of Kassel
Biogenesis of Lipid Droplets from the Endoplasmic Reticulum If grown axenically, Dictyostelium amoebae fail to build one cellular organelle, the lipid droplet. As soon as free fatty acids are added to the growth medium, or when amoebae are fed with bacteria, fat synthesis begins and lipid droplets are formed.
Kontakt:
Glormann

Mo 
19.01.2015
Seminarraum A.04.101
Theoretische Physik

14:15 
Quantenfeldtheorie (Forschungsseminar M.Phy.412)
Robert Czechowski Göttingen
TBA Kontakt:
K.H. Rehren

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 
Theoretischphysikalisches Seminar
Robin Steinigeweg Technical University of Braunschweig
Realtime relaxation of currents in spin1/2 chains: Progress by quantum typicality We use the concept of typicality to study the realtime dynamics of spin and energy currents in spin1/2 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 smallsystem data from exact diagonalization (ED) and existing shorttime data from timedependent 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 longtime 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 hightemperature 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. Kontakt:
Stefan Kehrein

Mi 
21.01.2015
Seminarraum A 03.101
Theoretische Physik

12:15 
Statistische Mechanik komplexer Systeme (Forschungsseminar M.Phy.410)
Alberto Giacomello Sapienza Università di Roma
Wetting of actual surfaces via atomistic and continuum string methods The string method is a general and flexible strategy to compute the most probable transition path for an activated process (rare event). I compare here the results for the CassieWenzel transition on a patterned, hydrophobic surface obtained via the atomistic string method in the density field, the continuum "interface" string, and an approximate string, the socalled continuum rare events method. A critical discussion of the three approaches is made, and the physical implacations for superhydrophobicity are analyzed. If time permits, the mechanism of advance and retreat of a liquid front on surfaces with defects will also be discussed as computed from a combination of microscopic DFT and the string method; these results shed light on contact angle hysteresis on anorough surfaces. Kontakt:
Marcus Müller

Do 
22.01.2015
Sitzungssaal Mathematik
Theoretische Physik

14:15 
Graduiertenkolleg 1493
Igor Khavkine Trento
Analyticity is an unnecessary hypothesis in the renormalization of locally covariant QFT Finite renormalization freedom in locally covariant quantum field theories on curved spacetime is known to be tightly constrained, under certain standard hypotheses, to the same terms as in flat spacetime up to finitely many curvature dependent terms. These hypotheses include locality, covariance, scaling, and continuous and analytic dependence on the metric and coupling parameters. The analytic dependence hypothesis is somewhat unnatural, because it requires that locally covariant observables (which are simultaneously defined on all spacetimes) depend continuously on an arbitrary metric, with the dependence strengthened to analytic on analytic metrics. Moreover the fact that analytic metrics are globally rigid makes the implementation of this requirement at the level of local algebras of observables rather technically cumbersome. We show that the conditions of locality, covariance and scaling, in conjunction with the microlocal spectral condition, are actually sufficient to constrain the allowed finite renormalizations equally strongly, making both the continuity and the analyticity hypotheses unnecessary. The key step in the proof uses the nonlinear Peetre theorem on the characterization of differential operators. Based on [arXiv:1411.1302]. Kontakt:
K.H. Rehren

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

Mo 
26.01.2015
SR4
Theoretische Physik

14:15 
Kontakt:
K.H. Rehren

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 ChernSimons theory as a fully local field theory in this sense. I show how classical ChernSimons theory and its "prequantization" (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 "p1structure" (Atiyah 2framings). 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 
Kontakt:
K.H. Rehren

Juni 2015  
Di 
23.06.2015
SR 3, Institut für Theoretische Physik, A03.101
SFB 937

17:00 
Seminar
Tilman Schäffer Universität Tübingen
TBA Kontakt:
Glormann
