Nonlinear Dynamics and Disorder Effects in Bose-Einstein Condensates, Degenerate Fermi Gases and Mixtures

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Bose-Einstein condensates (BECs), degenerate Fermi gases and Bose-Fermi mixtures offer unique opportunities for the investigation of nonlinear dynamics in quantum systems. The PI and his group have developed new experimental techniques to generate and observe quantum shock waves in BECs. Extensions of these techniques will be employed to investigate extreme nonlinear quantum dynamics and disorder phenomena in new and unexplored regimes. For example, two-dimensional shocks in BECs are predicted to exhibit intriguing richness of dynamical phenomena including a proliferation of quantized vortices at the shock front, a variety of instabilities, a novel phase diagram for oblique shock, and potentially a transition to a turbulent regime. The quantum shock experiments will provide much needed benchmark tests for theoretical treatments of quantum dynamics. In addition, degenerate Fermi gases as well as Bose-Fermi mixtures will be employed for the investigation of new physics in the presence of disorder potentials and to address central questions of quantum percolation.While all the experiments will be conducted with ultracold quantum degenerate gases, the importance of this research goes beyond the field of atomic physics. A precise understanding of the dynamics revealed by the experiments is essential for a variety of other systems governed by a nonlinear equation similar to the one applicable to BECs. Dispersive shock waves exist in plasmas, shallow water systems, and nonlinear optical media, to name a few. Nonlinear phenomena in optical media are of great importance e.g. for high-speed communication. The investigations of disorder phenomena will be highly relevant for developing a detailed understanding of complex materials such as glass phases, dirty superconductors, granular metals, etc. Disorder effects also play important roles in various nontrivial acoustics and optics phenomena. The experiments allow students at all levels to gain experience in an unusually broad range of modern physics and lab techniques. Ongoing cooperation with local, national and international theory groups provide the students with ample opportunities for exchanging scientific ideas. The PI's lab is also actively participating in a variety of educational and outreach activities, including regular visits from high school classes.