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

玻色-爱因斯坦凝聚体、简并费米气体和玻色-费米混合物为研究量子系统中的非线性动力学提供了独特的机会。PI和他的团队开发了新的实验技术来产生和观察BEC中的量子冲击波。这些技术的扩展将被用来研究极端非线性量子动力学和新的和未探索的制度的无序现象。例如，在BEC中的二维激波被预测为表现出有趣的丰富的动力学现象，包括在激波前沿的量子化涡的增殖，各种不稳定性，斜激波的新相图，并可能过渡到湍流状态。量子冲击实验将为量子动力学的理论处理提供急需的基准测试。此外，简并费米气体以及玻色-费米混合物将被用于在无序势存在的情况下研究新物理，并解决量子渗流的核心问题。虽然所有实验都将用超冷量子简并气体进行，但这项研究的重要性超出了原子物理学领域。一个精确的理解的动态实验所揭示的是必不可少的各种其他系统所管辖的一个非线性方程类似的一个适用于BEC。色散激波存在于等离子体、浅水系统和非线性光学介质中，仅举几例。光学介质中的非线性现象非常重要，例如对于高速通信。无序现象的调查将是高度相关的复杂材料，如玻璃相，脏超导体，颗粒状金属等的详细了解无序效应也发挥了重要作用，在各种非平凡的声学和光学现象。这些实验使各级学生能够在现代物理和实验室技术的异常广泛的范围内获得经验。与当地，国家和国际理论团体的持续合作为学生提供了交流科学思想的充分机会。PI的实验室还积极参与各种教育和推广活动，包括高中班级的定期访问。

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.