# Non-equilibrium Statistical Physics (Matthias Krüger)

Emmy Noether Research Group

(Quantum-)thermal fluctuations are a fundamental part of our world, as they have a large impact on the properties of our daily observed surroundings. In equilibrium, such fluctuations are well understood in the framework of statistical physics and thermodynamics. In non-equilibrium, however, many of the helpful tools and theorems which were developed in equilibrium statistical physics are not applicable. This makes non-equilibrium on the one hand harder to understand and treat theoretically, but on the other hand often also richer in phenomenology. Our group aims at improving both the theoretical description and understanding of non-equilibrium fluctuations, specifically in the two fields of quantum electrodynamics (QED) and soft condensed matter.

In QED, we investigate mostly radiative heat transfer and Casimir interactions. Among other things, we try to understand and describe the physical mechanisms at smaller and smaller length scales, aspiring to eventually reach non-equilibrium physics at the nano-scale.

In soft matter we investigate properties of driven suspensions far from equilibrium, employing and advancing microscopic theories like density functional theory. Here we are e.g. interested in finding the proper variables to be preset, i.e., the appropriate ensemble to be used in the description of realistic experimental setups. The question of ensembles is much less established in non-equilibrium compared to equilibrium systems.