Institut für Theoretische Physik
Start / Aktuell
Mai  2015
Mi
27.05.2015
Besprechungsraum Astrophysik (BZA, F.04.122)
Astrophysik
13:00
Cosmology Seminar Göttingen

Chris Kouvaris
CP3-origins, Odense, Dankmark

Dark Matter: From Stars to Detectors

I will talk about how observations of compact stars can give us information about the nature of dark matter that cannot be obtained otherwise. I will also talk about dark matter signals in underground detectors that exhibit a diurnal modulation and how we can exploit this fact to pinpoint the parameter space where dark matter might be.

Kontakt: Ricardo Catena
Mi
27.05.2015
Seminarraum 0.79, Am Faßberg 17, 37077 Göttingen
MPIDS
14:15
Kolloquium

PD Dr. Franz Xaver Bronold
Greifswald University

Mie scattering by charged dielectric particles:
An electric probe with optical read-out?

Measuring the charge of dust particles immersed in a gas discharge remains a great challenge. Most methods in use require a precise knowledge of the plasma parameters at the location of the particle, which is however in general not available, resulting in large uncertainties of the measurement. To remedy this shortcoming we studied Mie scattering by negatively charged dielectric particles with the goal to use it as an optical mean to measure the charge of the particle. We investigated in particular anomalous Mie scattering originating from a transverse optical phonon resonance in the particle's dielectric function. The surplus electrons affect the maximum of the extinction efficiency, which in turn could be used as a charge diagnostics. In my talk I will focus on dielectric core-shell particles where the additional charges are confined to the shell region. The charge sensitivity of the antibonding anomalous resonance is rather high making it a good candidate for the proposed optical charge measurement. If time permits I will also briefly address the material dependence of the particle charge.

Kontakt: André Schella
Mi
27.05.2015
GAUSS-WEBER-Hörsaal (HS 5, E00.109)
Fakultät für Physik
20:00
Probevorlesung

Dr. Ulrike Blumenschein
II. Physikalisches Institut

DER KERNSPIN UND SEINE TECHNISCHE BEDEUTUNG

Probevorlesung im Rahmen eines Habilitationsverfahrens

Mi
27.05.2015
GAUSS-WEBER-Hörsaal (HS 5, E00.109)
Fakultät für Physik
21:00
Probevorlesung

Dr. Lucas Goehring
MPI Dynamik und Selbstorganisation

Climate sensitivity: why do we have ice ages

Probevorlesung im Rahmen eines Habilitationsverfahrens

Do
28.05.2015
Seminarraum A.04.101
Theoretische Physik
14:15
Theoretisch-physikalisches Seminar

Michele Burrello
MPI Garching

Topological Properties in a Ladder Model of Ultracold Fermions

The recent successes in coupling ultracold gases to synthetic gauge potentials show the exceptional possibilities of such setups in studying and probing many-body quantum physics. In this talk I will review some aspects of the theory of topological phases of matter and I will describe how synthetic magnetic fields and spin-orbit couplings allow us to simulate topological insulators and superconductors in optical lattices. I will focus in particular on a ladder model of fermions which mimics a one-dimensional topological superconductor and presents fractionalized edge modes. The physical observables suitable for the detection of topological phases in this system will be examined and I will discuss their robustness in the presence of Hubbard interactions.

Kontakt: D. Fioretto
Fr
29.05.2015
Seminarraum EG (0.77), Am Faßberg 17
MPIDS
10:15
Seminar

Prof. Iker Zuriguel
Universidad de Navarra, Spain

Flow and clogging of many-particle systems passing through bottlenecks

When a group of particles or live beings pass through a narrow orifice, the flow might become intermittent due to the development of clogs that obstruct the constriction. Despite the importance of clogging in fields such as crowd dynamics, colloids, granular and active matter, a general framework -in which research in such a wide variety of scenarios can be encompassed- is still lacking. The goal of this talk will be precisely this. To this end, we analyse the statistical properties of the intermittent flow in different experiments (granular media within vibrated silos and a flock of sheep) and simulations (pedestrians and colloids). From these, we reveal a common phenomenology that allows us to rigorously define the transition to clogging. Finally we will explore the main variables involved, which will be then grouped into three generic parameters.

References:

I. Zuriguel et al., Clogging transition of many-particle systems flowing through bottlenecks, Sci. Rep. 4, 7324 (2014).

I. Zuriguel et al., Silo clogging reduction by the presence of an obstacle, Phys. Rev. Lett. 107, 278001 (2011).

Fr
29.05.2015
MPS - Auditorium
MPI für Sonnensystemforschung
11:00
Rosetta-Seminar

Dennis Bodewits

'OSIRIS observations of the physics and chemistry in the coma of comet 67P/CG'



Fr
29.05.2015
Seminarraum 11, C3.101
SFB 1073
14:15
SFB Seminar

Prof. Bettina V. Lotsch
Max-Planck-Institut für Festkörperphysik, Stuttgart

Functional frameworks as platforms for energy conversion and storage

The conversion of sunlight into storable chemical fuels has been identified as a viable strategy to alleviate future energy shortage. To this end, the development of efficient photocatalysts capable of splitting water into hydrogen and oxygen has become a major thrust in materials science. While heterogeneous systems excel through their stability, homogeneous catalysts offer the potential to tune every step in the photocatalytic mechanism through molecular engineering. Combining the best of both worlds thus opens up new possibilities for the design of tailor-made photocatalysts. Here, I will discuss the development of polymeric photocatalysts based on 1D or 2D carbon nitrides and covalent organic frameworks (COFs),1 which are earth-abundant and molecularly tunable classes of organic semiconductors. Possible catalyst optimization strategies – through doping2 exfoliation,3 active site engineering,4 and hybridization with bio-inspired cocatalysts5 – will be reviewed and the potential of nitrogen-rich frameworks for carbon capture and storage applications will be discussed. 1. L. Stegbauer, K. Schwinghammer, B. V. Lotsch, Chem. Sci. 2014, 5, 2789−2793. 2. K. Schwinghammer, B. Tuffy, M. B. Mesch, E. Wirnhier, C. Martineau, F. Taulelle, W. Schnick, J. Senker, B. V. Lotsch, Angew. Chem. Int. Ed. 2013, 52, 2435–2439. 3. K. Schwinghammer, M. B. Mesch, V. Duppel, C. Ziegler, J. Senker, B. V. Lotsch, J. Am. Chem. Soc. 2014, 136, 1730−1733. 4. V. W.-h. Lau, M. B. Mesch, V. Duppel, V. Blum, J. Senker, B. V. Lotsch, J. Am. Chem. Soc. 2015, 137, 1064–1072. 5. C. A. Caputo, M. A. Gross, V. W. Lau, B. V. Lotsch, E. Reisner, Angew. Chem. Int. Ed. 2014, 53, 11538–11542.


Juni  2015
Mo
01.06.2015
Sitzungszimmer Mathematik
Theoretische Physik
14:15
Born-Hilbert-Seminar

D. Buchholz
Göttingen

Macroscopic aspects of the Unruh effect: On the heat of acceleration

Within the framework of quantum field theory, macroscopic concepts pertaining to the Unruh effect are introduced and used in order to clarify its physical manifestations. It is explained why, contrary to the conventional doctrine, an accelerated observer in an inertial vacuum state will not be immersed in a "gas of thermal quanta" even though his thermometer indicates a non-zero temperature.

Kontakt: K.-H. Rehren
Mo
01.06.2015
Max-Born-Hörsaal (HS2), Friedrich-Hund-Platz 1
Fakultät für Physik
16:30
Göttinger Physikalisches Kolloquium

Prof. Dr. Roser Valenti
Universität Frankfurt

Towards computational design of correlated materials

Unconventional superconductivity with high critical temperatures, frustrated magnetism, spin liquid behavior, heavy fermions or Heisenberg-Kitaev phenomenology are a few examples of exotic phases in correlated materials. In a correlated system electrons experience strong Coulomb repulsion and one of the big challenges in solid state physics is the microscopic description of such systems. Moreover, being able to understand these materials implies the possibility of designing compounds with desirable properties.

In this talk I will review the world of some families of correlated materials ranging from unconventional superconductors, frustrated magnets and possible correlated Dirac metals and present some strategies on how to model them microscopically.


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