The Emergence of Order in Ultracold Quantum Gases

我们周围的世界是不断变化的。从这些动态中，可以出现平衡秩序。但是，我们称之为生命的日常动态本身不可能处于平衡状态，因为（例如）离子浓度的梯度会驱动神经的动作电位。非平衡动力学在早期宇宙的宇宙学、经济市场动力学、重离子碰撞中的夸克-胶子等离子体以及超导体的电阻率中得到了广泛的研究。****我们提出用超冷原子实验来研究新秩序的动力学。在过去的十年里，我们已经学会了如何研究中性钾的费米子同位素，它可以模拟固体中电子的行为，甚至可以探索固体材料无法实现的场景。在任何一种情况下，我们使用冷原子的“量子模拟”方法的优势是前所未有的调整和表征样品的能力。这给我们探索的模型留下了不确定性的空间；因此，观察到的任何现象或行为都与模型有直接联系。******我们提出的研究将解决关于非平衡量子动力学的三个开放问题。第一个系列的实验探索自旋扩散在强相互作用的费米气体中发生的速率。我们希望解决当前关于维数对耗散影响的争论。第二个系列的实验探索p波相关性的出现。我们的目标是创造一种具有独特和可控性能的超冷p波材料。纵波超流体的激发包括马约拉纳态，因其在量子信息处理中的前景而被广泛寻求。第三条探索路线是使用一种新开发的显微镜来寻找光晶体中原子的磁性排列。******这项研究计划的成功将阐明粒子间相互作用如何限制弛豫过程，产生磁性，并使新的超流体状态成为可能。用冷原子解决这些问题是一种高风险、高回报的实验，因为实验具有挑战性，理论也很难理解，但潜在的好处是巨大的：我们的研究结果将直接洞察范式模型中不可解的动力学

The world around us is constantly changing. Out of these dynamics, equilibrium order can emerge. But the everyday dynamics we identify as life itself cannot exist in equilibrium, because (for instance) gradients in ion concentrations drive action potentials in nerves. Non-equilibrium dynamics are studied diversely, in cosmology of the early Universe, in economic market dynamics, in quark-gluon plasma in heavy-ion collisions, and in the resistivity of superconductors.****We propose experiments with ultracold atoms that study the dynamics of emerging order. Over the past decade, we have learned how to study a fermionic isotope of neutral potassium, which can emulate the behaviour of electrons in solids, or even explore scenarios inaccessible with solid materials. In either case, the advantage of our “quantum emulation” approach using cold atoms in is an unprecedented ability to tune and characterise the sample. This leaves no room for uncertainty about the model we explore; so that any phenomena or behaviour observed has a direct connection to the model.******Our proposed research will address three open questions about non-equilibrium quantum dynamics. A first series of experiments explores the rate at which spin diffusion occurs in a strongly interacting Fermi gas. We hope to resolve a current debate regarding the effect of dimensionality on dissipation. A second series of experiments explore the emergence of p-wave correlations. We aim to create an ultracold p-wave material with unique and controllable properties. Excitations of p-wave superfluids include Majorana states, widely sought for their promise in quantum information processing. A third line of exploration uses a newly developed microscope to search for magnetic ordering of atoms in a crystal of light.******Success of this research program would elucidate how inter-particle interactions limit relaxation processes, give rise to magnetism, and enable new superfluid states. Addressing these issues with cold atoms is a type of high-risk, high-reward experiment, because the experiments are challenging and the theory is poorly understood, and yet the potential benefit is tremendous: the results of our investigations will yield direct insight into the unsolvable dynamics of paradigmatic models.**