Institut für Theoretische Physik
Start / Aktuell / Institut
November  2014
Fr
07.11.2014
SR 4, Institut für Theoretische Physik, A03.101
SFB 937
14:00
Seminar

Roland Netz
FU Berlin

DNA dynamics, protein force spectroscopy and viscoelastic properties of polymeric networks



Kontakt: Glormann
Di
18.11.2014
SR 3, Institut für Theoretische Physik, A03.101
SFB 937
17:15
Seminar

Frieder Mugele
University of Twente (NL)

TBA



Kontakt: Glormann
Do
20.11.2014
Seminarraum A 03.101
Theoretische Physik
12:00
Statistische Mechanik komplexer Systeme (Forschungsseminar M.Phy.410)

Guojie Zhang
MPI Mainz

Hierarchical Modeling of Highly Entangled Polymer Melts:
Equilibration, Entanglements & Rheology



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

Yael Roichman
Tel Aviv University

TBA



Kontakt: Glormann
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
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.


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