Interacting atoms in optical lattices

这个项目将研究原子在一维(1D)气体中的量子力学行为。这一点很重要，因为一维气体是少数几个可以对其量子态做出准确定量预测的多体系统之一。相比之下，大多数其他量子多体系统不是“可积的”，因此描述起来更具挑战性。在这个项目中，将制备超冷原子，然后利用激光将其限制在一维陷阱中。这些一维气体中的原子动量分布将在各种条件下被精确测量，这将作为正在开发的先进理论方法的基准测试，这些方法正在开发以了解多体量子系统。该项目还被设计用来观测量子多体现象，如“动力学费米化”和“预热化”。这些实验将激发新的理论方法，这些方法也将与核和凝聚态物理相关，并将导致对超导、磁性和量子信息处理等量子多体现象的更深层次理解。从事这个项目的学生将学习先进的原子物理研究技术，这将为他们在学术界或高科技行业的职业生涯做准备。这个团队将使用一种比以前方法更精确的技术，对一维玻色气体的动量分布进行三套测量。第一组测量将是中等和强耦合气体在一定温度范围内的平衡动量分布。这些将与新的理论计算进行比较。任何不一致都表明，一维气体没有热分布，尽管它们从平衡的三维气体开始进行极其温和的制备。第二组测量将涉及动力学费米化的第一次观测，其中Tonks-Girardeau气体最初的玻色子动量分布转变为非相互作用费米气体的玻色子动量分布，从而直接揭示了该系统中潜在的守恒量。第三组测量将测量量子猝灭后预热的早期阶段。猝灭将是布拉格散射脉冲，与点接触相互作用相关的后续演化部分比陷阱中的典型演化快得多。将与最近发展的理论进行比较。对于后两组测量，在中间耦合区域进行这些动力学计算超出了现有的理论方法。但研究人员提议也在那里进行实验，从而为理论家设定了努力的基准。

This project will study the quantum mechanical behavior of atoms in one dimensional (1D) gases. This is important because 1D gases are one of the few many-body systems for which exact quantitative predictions can be made about their quantum states. In comparison, most other quantum many-body systems are not "integrable," and therefore are much more challenging to describe. For this project, ultracold atoms will be prepared and then confined in 1D traps using laser light. The atomic momentum distributions in these 1D gases will be precisely measured under a variety of conditions, and this will serve as a benchmark test for advanced theoretical approaches that are being developed to understand many-body quantum systems. This project is also designed to observe quantum many-body phenomena such as "dynamical fermionization" and "prethermalization." These experiments will motivate new theoretical approaches that will also be relevant for nuclear and condensed matter physics, and will lead to a deeper understanding of quantum many-body phenomena such as superconductivity, magnetism, and quantum information processing. Students working on this project will learn advanced atomic physics research techniques that will prepare them for careers in academia or high tech industry.This team will work on three sets of measurements related to the momentum distributions of 1D Bose gases, using a technique that is dramatically more precise than previous approaches. The first set of measurements will be of equilibrium momentum distributions with intermediately and strongly coupled gases, for a range of temperatures. These will be compared to new theoretical calculations. Any disagreement would indicate that the 1D gases do not have a thermal distribution, despite their extremely gentle preparation starting from equilibrated 3D gases. The second set of measurements will entail the first observation of dynamical fermionization, where the initially bosonic momentum distribution of a Tonks-Girardeau gas transforms into that of a non-interacting Fermi gas, thus directly revealing the underlying conserved quantities in this system. The third set of measurements will measure the early stages of prethermalization after a quantum quench. The quench will be a Bragg scattering pulse, and the part of the ensuing evolution that is related to the point contact interactions is much faster than typical evolution in a trap. Comparisons with recently developed theory will be made. For the latter two sets of the measurements it is beyond existing theoretical methods to perform these dynamical calculations in the intermediate coupling regime. But the investigators propose to perform the experiments there as well, thus setting benchmarks for theorists to work toward.