SFB925 Workshop 2013

Speaker: Wilfried Wurth

Title: "Competing Interactions – Complex Phase Diagrams"

Abstract:

Ground state properties of complex solids are often quite difficult to predict. Simple models based on an independent particle approach for the carriers and a decoupling of the electronic and nuclear degrees of freedom which are very successfully used to explain the properties of most elemental solids fail in many cases.
To understand the physics that determines the ground state properties of more complex solids it is necessary to explicitly include many-body interactions as well as the influence of competing interactions between charge, spin and lattice degrees of freedom.
In the lecture I will give some simple examples for the consequences of such an approach and will try to discuss a few examples of complex phase diagrams resulting from competing interactions.

Speaker: Markus Drescher

Title: “Attosecond Science"

Abstract:

Our recently acquired ability to observe physical processes with attosecond precision has attracted a lot of attention in the scientific community. The promise to observe nature on the generic time scale of electrons has inspired a wealth of quite different experimental approaches. Most of them rely on the capabilty to measure and control both envelope and phase of a light pulse with a precision of a fraction of the light period. A selection of such approaches will be presented as examples for time metrology at the current technical limits.

Speaker: Ludwig Mathey

Title: "Dynamic and equilibrium phase transitions"

Abstract: 

In this lecture, I discuss phase transitions in equilibrium, and dynamic phase transitions following a quench. As an example for a thermal phase transition I discuss Bose-Einstein condensation, and as an example for a quantum phase transition the quantum transverse Ising model. Following a quench, a many-body system displays numerous dynamic effects. Here, I discuss two of them. On the shortest time scale, the system displays so-called light cone dynamics: The correlation functions of the system relax to a thermalized or prethermalized state in a way in which the resulting new behavior of the correlation functions builds up with the fastest velocity of the system. On a longer time scale the system displays critical scaling, when the system is ramped across a second-order phase transition. The resulting defects that are generated are particularly long-lived if they have a topological character, as in the Kibble-Zurek mechanism.