The Project Areas - Funding Period I (10/2009 - 03/2014)

To illustrate the variety of Nonequilibrium Collective Dynamics
in different systems, we have chosen within hard and soft condensed
matter three focused project areas:

• A - Hard Matter [1]: Nonlinear transport and quantum optics in semiconductors;
• B - Soft Matter [2]: Collective dynamics and hydrodynamic interactions in complex fluids;
• C - Biological Systems [3]: Self-organization and nonlinear waves in active media,

and, in addition:

• Postdoctoral Research Project [4]: Dynamic density functional theory for active particles.

These project areas represent a multitude of different entities that display
collective dynamics ranging from electrons, excitons, phonons, and
photons in semiconductor materials, to colloidal spheres, rods,
and proteins in aqueous solvents, and to cellular objects such as
bacteria, neurons, heart, and multinuclear cells. It will be one
task of the participating scientists and students to create links
between the complex behavior of these different entities based,
e.g., on the type of interactions or the type of governing equations.
The equations comprise different physical mechanisms for nonlinearity,
dissipation, and external fields that ultimately determine the
collective dynamics. As we demonstrate below some of these links already
exist. The RTG will discover and establish new links, especially with such
systems that have not or hardly been studied from the perspective of
nonlinear dynamics.

In project area A semiconductor nanostructures are used to explore
the fascinating correlations within few particle systems in order
to unravel the quantum nature of electrons, excitons, and photons in a
dissipative ("phononic") environment. On a larger scale, an ensemble
of quantum dots generates, under laser condition, a variety of nonlinear
dynamic responses or it offers the possibility to tune the propagation
of a light pulse from the ballistic to the diffusive regime.

Project area B deals with the collective dynamics of different
colloidal objects such as spheres, nanorods, and proteins in a liquid
environment. Driven into the nonequilibrium by external fields,
such as magnetic, light, and shear fields, a wealth of dynamic
structure formation is expected and explored. On the other hand,
the use of an ensemble of "synchronized" self-propelling
molecular machines for active microfluidics is investigated.

In project area C active media that constantly convert chemical
energy into motion are studied. In an experimental and theoretical
project, we address chemically interacting bacteria that form
a highly organized dynamical and complex structure, called biofilm.
Furthermore, studies on nonlinear excitation waves in neural systems and
in the heart or a large multinuclear cell (where they trigger
mechanical deformations) point towards concrete medical applications.

The different projects, although mostly theoretical, benefit
from new experimental techniques that allow one to explore new
regimes, e.g., by the careful placement of quantum dots, by optical
tweezers which allow one to grab small objects, or by microfluidic
techniques which are used to apply a well-controlled flow field on the
micron scale.