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Kolloquium

Thema:

Thermodynamics and order beyond equilibrium -- from Floquet thermalisation to time crystals

Datum:

30.10.17

Uhrzeit:

16:15

Ort:

H6

Vortragender:

Prof. Dr. Roderich Moessner

MPI für Physik komplexer Systeme Dresden

Inhalt:

The field of thermodynamics is one of the crown jewels of classical physics. However, only comparatively recently, due to the advent of experiments in cold atomic systems with long coherence times, has our detailed understanding of its connection to quantum statistical mechanics seen remarkable progress. Extending these ideas and concepts to the non-equilibrium setting is a challenging topic, in itself of perennial interest. Here, we study perhaps the simplest non-equilibrium class of quantum problems, namely Floquet systems, i.e. systems whose Hamiltonians depend on time periodically, H(t + T) = H(t). For these, there is no energy conservation, and hence not even a natural concept of temperature. We find that it is nonetheless possible to identify several fundamentally distinct thermodynamic ensembles. We also ask if there exists a sharp notion of a phase in such driven, interacting quantum systems. Disorder turns out to play a crucial role, enabling the existence of states which are straightforward analogues of equilibrium states with broken symmetries and topological order, while others--genuinely new to the Floquet problem--are characterized by a combination of order and non-trivial periodic dynamics. This work was done in collaboration with Arnab Das, Vedika Khemani, Achilleas Lazarides and Shivaji Sondhi. References: Phys. Rev. Lett. 112, 150401 (2014); Phys. Rev. E 90 , 012110 (2014); Phys. Rev. Lett. 115, 030402 (2015); Phys. Rev. Lett. 116, 250401 (2016)

Ansprechpartner:

J. Schnack

Kolloquium Mathematische Physik

Thema:

lecture hall 3
The Riemann Hypothesis: recent perspectives on a grand mathematical challenge

Datum:

03.11.17

Uhrzeit:

16:45

Ort:

H3

Vortragender:

Jon Keating

University of Bristol

Inhalt:

Ansprechpartner:

G. Akemann

Seminar Hochenergiephysik

Thema:

Complex Langevin simulations and the QCD phase diagram

Datum:

14.11.17

Uhrzeit:

14:15

Ort:

D6-135

Vortragender:

Benjamin Jaeger

IMADA, Univ. of Southern Denmark, Odense

Inhalt:

The sign problem appears in lattice QCD as soon as a non-vanishing Baryon chemical potential is studied. This prevents direct simulations to determine the phase structure of the strongly interacting matter. Complex Langevin simulations have been successfully used for various models or approximations of QCD. However, in some scenarios it converges to incorrect results. Here I will discuss a new method that keeps complex Langevin simulations close to the SU(3) manifold and hereby improving the convergence. I will further discuss its application towards the ultimate goal of simulating fully dynamical QCD.

Ansprechpartner:

Ch. Schmidt

Seminar Kondensierte Materie

Thema:

Quantendynamik von Erwartungswerten unter dem Einfluss von Stoerungen des Hamiltonoperators

Datum:

27.10.17

Uhrzeit:

14:00

Ort:

V2-205

Vortragender:

Lars Knipschild

Universitaet Osnabrueck

Inhalt:

Ansprechpartner:

Peter Reimann

Seminar Mathematische Physik

Thema:

Perturbing an isoradial triangulation and the effect on its discrete Kähler operator

Datum:

26.10.17

Uhrzeit:

16:00

Ort:

D5-153

Vortragender:

Jeanne Scott

University of Leeds

Inhalt:

The David-Eynard discrete Kähler operator is a hermitian operator associated to any finite or infinite triangulation of the plane with the property that it specialises to Kenyon laplacian when the triangulation is infinite an isoradial (with unit radius). In the periodic case the log-determinant of Kenyon's laplacian can be expressed as a weighted sum of edges within the fundamental domain. Together with F. David, we consider the effect of smoothly perturbing the vertex positions of a periodic isoradial triangulation upon this kind of local formula for the log-determinant.

Ansprechpartner:

Gernot Akemann

Seminar AG Zufallsmatrizen

Thema:

tba

Datum:

22.11.17

Uhrzeit:

14:15

Ort:

V3-201

Vortragender:

Giuseppa Alfano

Politecnico di Torino, Department of Applied Science and Technology

Inhalt:

Ansprechpartner:

Gernot Akemann



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  •  Olaf Kaczmarek
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