Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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Transport and Nonlinear Dynamics in Mesoscopic Systems

Head of group:  Fleischmann, Ragnar 

Micro- and nanoscale semiconductor electronic and optical devices are prime examples of mesoscopic systems that inspire the activities of our group. Not only are these interesting from a technological point of view but provide superb models for studying fundamental aspects of mesoscopic wave propagation, Hamiltonian nonlinear dynamics, quantum chaotic systems and the dynamical effects of disorder, leading to a transition from ballistic transport to branched flows and localization. Branched flow, however, turns out to be a very general phenomenon that leads to extreme events in a large variety of systems, where waves propagate through complex media, from the micrometer to the thousands of kilometer scale. Another focus of our activities is the dynamics of ultracold atoms (Bose-Einstein-condensates) in optical lattices, where we study phenomena like self-localization, a dynamical phase transition from diffusive  localized motion due to the interplay of nonlinearity and boundary dissipation.


Projects:

The path to self-trapping of Bose-Einstein-Condensates

The Bose Einstein condensates in (leaky) optical lattices show an intriguing transition to self-trapping into intrinsic localized states, which we study theoretically.

Random focusing of tsunami waves

We explore how tsunami waves can be focussed by even minute height variations in the ocean floor topography and study the impact of this effect on tsunami predictability.

Fluctuations in human musical rhythms

Music generated by computers and rhythm machines sometimes sounds unnatural. One reason for this is the absence of small inaccuracies that are part of every human activity. Professional audio software therefore offers a so-called humanizing technique, by which the regularity of musical rhythms can be randomized to some extent. But what exactly is the nature of the inaccuracy in human musical rhythms? Studying this question for the first time, we found that the temporal rhythmic fluctuations exhibit scale-free long-range correlations, i.e., a small rhythmic fluctuation at some point in time does not only influence fluctuations shortly thereafter, but even after tens of seconds. While this characterization is relevant for neurophysiological mechanisms of timing, it also leads to a novel concept for humanizing musical sequences. Comparing with conventionally humanized versions listeners showed a high preference for long-range correlated humanized music over uncorrelated humanized music.

Wave dynamics in correlated weakly scattering random media

Waves propagating through a weakly disordered medium are surprisingly focused into branch-like structures. This very general phenomenon can be observed diverse systems ranging from the two-dimensional electron gases in semiconductors to the focusing of tsunami waves.

Avalanches in Bose-Einstein Condensates

The dynamics of Bose-Einstein condensates in leaky optical lattices is studied (in the mean field limit). For some critical values of the interatomic interaction strength, the current of atoms leaving the trap exhibits avalanches that follow a power-law distribution and indicate the existence of a novel phase transition.

Disorder in Quantum Systems with Antilinear Symmetries

We study the influence of disorder on the pseudo-hermitian phase of (generalized) PT-symmetric systems.

People working in this Group:

Name Email Phone
George Datseris send email   [+49-(0)551-5176-414
Ragnar Fleischmann send email   [+49-(0)551-5176-410
Theo Geisel send email   [+49-(0)551-5176-400
Lucas Gitter send email   [ No phone specified
Gerrit Green send email   [+49-(0)551-5176-434

Selected publications of the group