One of the hottest topics in statistical physics these days is the behaviour of "active matter", i.e. systems that are driven by internal or external energy consumption, so that they do not obey the normal laws of equilibrium statistical mechanics. Bacterial populations (which I spend most of my time working on) are an example of active matter, but non-living active matter also exists: for example, there are several different ways to make colloidal swimming particles.
I have been involved in several different projects investigating the soft matter physics of active matter. Together with Chantal Valeriani and Davide Marenduzzo, I investigated what happens when colloids secrete particles (which could be polymers or a different osmolyte); we called these particles active colloidal "chuckers". Also on the topic of osmosis, I worked with my student Tom Lion to investigate how the laws of osmosis are affected when the solute particles are active in the sense that they are either at a higher "temperature" than the surrounding solvent, or they are actually able to swim. We discovered that these active solutes exert a much higher osmotic pressure than their passive counterparts, but this cannot be easily described by an effective temperature, as active motility sometimes is.
In recent years, I have also been involved in a project with Mike Cates and Davide Marenduzzo, and their postdocs Joakim Stenhammar, Raphael Wittkowski and others, to investigate the phase behaviour of "active Brownian particles": repulsive spherical colloids which are able to swim, but also diffuse both translationally and orientationally. We used large-scale simulations to investigate the behaviour of these systems in 2D and 3D, and also were able to match their phase behaviour to the predictions of continuum theories, both in simple form and in a more detailed theoretical study in which we effectively derive a Cahn-Hilliard equation for active particles.
Here is a great 3 minute video of our PhD student Freya Bull describing her research modelling bacterial infection of a urinary catheter!
We are searching for a part-time computer systems administrator for our group in Jena. Please contact us if you are interested!
Welcome to Ariane Zander who has joined us as a technician in our lab!