Institut für Theoretische Physik
Start / Aktuell
November  2014
Seminarraum Astrophysik (SR 17, F 05.104)
SFB 963
SFB 963 Seminar

Prof. Moira Jardine
SUPA, School of Physics and Astronomy, University of St. Andrews

The Space Weather of other Suns

"Space Weather" describes the impact that the Sun has on its environment through the magnetically powered flares, mass ejections and wind that it produces. Although the Sun is a relatively inactive star, the impact of a large solar mass ejection can damage satellite electronics, shut down terrestrial power grids and disrupt radio communications. On more active stars, we might expect even more dramatic space weather and a greater impact on any orbiting planets. In this talk I will describe how we can use observations that reveal the geometry of stellar magnetic fields to understand the nature of the accompanying space weather.

Kontakt: Jeffers
Seminarraum Astrophysik (SR 17, F 05.104)
Astrophysikalisches Kolloquium

Andreas Becker
AG statistische Physik, Institut für Physik, Universität Rostock

Modeling Giant Planets and Brown Dwarfs using ab initio equation of state data for hydrogen and helium

Kontakt: Wicht, MPS

Dezember  2014
Sitzungszimmer Mathematik
Theoretische Physik

Jan Philip Solovej
University of Copenhagen


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

Manuel Kreye
Universität Göttingen


Kontakt: S. Kehrein
Max-Born-Hörsaal (HS2), Friedrich-Hund-Platz 1
Fakultät für Physik
Göttinger Physikalisches Kolloquium

Prof. Dr. Dieter Meschede
Universität Bonn

Discrete Quantum Walks with Neutral Atoms:
Driven Quantum Transport in an Optical Lattice

A „quantum walker“ takes discrete steps on a lattice: conditioned on its spin state (up or down) it is shifted one site left or right. After each step a coin operation rotates the spin which coherently couples the left and rightward motion. Therefore an initially localized particle becomes coherently distributed across a large number of lattice sites. A prominent feature of quantum walks is a linear expansion of the coherent spatial distribution with the number of steps N, in stark contrast to the diffusive, incoherent √N behaviour of the classic random walk. Quantum walks are of interest for simulating quantum transport phenomena, and they are a candidate for universal implementation of quantum algorithms. Quantum information is stored in the positions and spin states of the system. In our laboratory we are experimentally investigating quantum walks with individual neutral atoms stored in an optical lattice. We find linear expansion of the distribution up to 50 steps before coherent dynamics is significantly impaired by decoherence. We have shown that the motion of particles on a periodic lattice under the influence of a static force shows prominent features including Bloch oscillations, Anderson like localization, and the occurrence of anti-particles: in other words we can simulate all aspects of electron quasi particle quantum transport in a periodic potential and subject to an electric field. Our experiments are based on measurements of the position of the quantum walker which gives us access to so called non-invasive “ideal negative” measurements. We can directly illustrate and support the relevance of quantum superposition states by violating the Leggett-Garg inequality based on trajectory models. Finally, our experimental efforts to extend quantum walks with neutral atoms to two dimensions will be discussed.

Öffentliche Führung Astrophysik

Öffentliche Führung Astrophysi

Beobachtungsobjekte: Mond, Uranus, Ringnebel, Kugelsternhaufen
Thema des Vortrags: Astronomie in Südafrika - Exkursion 2014 (Dreizler et al.)

Das Institut für Astrophysik bietet in unregelmäßigen Abständen öffentliche Führungen mit Beobachtungsmöglichkeit am 50-cm-Spiegelteleskop an. Während der Führungen werden die Forschungs- und Ausbildungseinrichtungen des Instituts vorgestellt und, bei klarem Himmel, eindrucksvolle Himmelsobjekte (z. B. Mond, Planeten, Gasnebel, Sternhaufen, Galaxien) im Fernrohr gezeigt. Die Führungen werden durch eine halbstündige Präsentation zu einem aktuellen Thema aus der astronomischen Forschung ergänzt.

Kontakt: Reinsch
SR 3, Institut für Theoretische Physik, A03.101
SFB 937

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

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Last modified: Mon Mar 5 10:17:50 CET 2012