May 10 2016

16-18.05.2016: Visit of Shamik Gupta

Shamik Gupta (Max Planck Institute for the Physics of Complex Systems, Dresden, Germany) is visiting us. On Tuesday 17.05.2016 at 9 am in room 4.18 he will give a talk on 'Long-range interacting systems driven out of equilibrium'.

Abstract: Systems with long-range interactions have an inter-particle interaction potential that decays slower than 1/r^d in d dimensions. Examples are widespread, from plasmas, dipolar ferroelectrics and ferromagnets, to gravitational systems. After a brief introduction to unusual static and dynamic properties of long-range systems, I will dwell on the question: What happens when a long-range system is driven out of thermal equilibrium by, e.g., an impulsive kick? In similar situations, short-range systems would typically relax to another thermal equilibrium with a uniform temperature across the system. By contrast, a long-range system relaxes to non-Boltzmann nonequilibrium stationary states that support a non-uniform temperature profile across the system. More striking and counterintuitive is the observation of temperature inversion in such a state: denser parts of the system are colder than dilute ones. Such inversions occur in nature, e.g., in the solar corona and in interstellar molecular clouds. We demonstrate how an interplay of wave-particle interaction and spatial inhomogeneity offers a simple and appealing mechanism to explain temperature inversion in generic long-range systems.