Strongly Interacting Fermi Gases of Ultracold Atoms

超冷原子的强相互作用费米气体

• 批准号: 1506019
• 负责人: Martin Zwierlein
• 金额: $ 45万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506019&HistoricalAwards=false
• 关键词: Strongly; Interacting; Fermi; Gases; Ultracold

Our modern world is run by electrons--they flow through our smart phones, computers, and machines to carry out a myriad of tasks from data storage and calculations to heavy lifting when employed in electromagnets. It is surprising that we do not better understand how electrons work together. This award supports studies of a novel substance, an ultracold gas of strongly interacting atoms, which behaves in many ways like electrons. For example, just like a metal becomes "superconducting" at low temperatures and starts to conduct electricity without resistance, the atomic gas becomes "superfluid" and atoms flow without friction. However, scaled to the density of electrons in metals, superfluidity would occur in the atomic gas already far above room temperature, thanks to the strong interatomic interactions. Just like electrons, but also protons and neutrons, the atoms belong to the class of particles called fermions, which cannot share one and the same state. This requirement makes computations extremely difficult and experiments indispensable to learn about the behavior of fermions. Confined in an artificial "box" of light, the atomic Fermi gas will be a pristine platform to learn about the equation of state of strongly interacting fermions, as they occur in modern materials, for example high-temperature superconductors, but also in neutron stars and nuclear matter. With the help of these and other studies, we might be led to an understanding on how to realize room temperature superconductivity. The project also holds the potential for observing new states of fermionic matter such as a supersolid--a superfluid that is also ordered like a crystal. The research will present a stimulating learning experience for graduate students.Ultracold Fermi gases of atoms represent a paradigmatic form of fermionic matter, where all details of the interparticle interaction, the external confinement, and the spin composition are precisely known and under the control of the experimenter. This project employs a Fermi gas of Lithium-6 atoms to try to answer long-standing questions about 1) the thermodynamics of two- and three-dimensional systems, 2) the fate of fermionic superfluidity in the presence of spin imbalance and 3) non-equilibrium dynamics in fermionic superfluids. The Fermi gas will be confined in tailored potentials, in particular a homogeneous box potential and a hybrid harmonic-box potential. Creating a homogeneous Fermi gas will take away many of the existing experimental limitations in obtaining accurate thermodynamic information. The box potential allows accessing new phases of fermionic matter that have not been observed before. The Berezinskii-Kosterlitz-Thouless superfluid in two dimensions features algebraic order that would be masked in an inhomogeneous trap. A homogeneous 3D Fermi superfluid in the presence of spin imbalance should spontaneously break translational symmetry by forming a train of solitons, where excess fermions reside in the nodes of the order parameter. This describes the famous Larkin-Ovchinnikov (LO) state, a supersolid phase of matter that has not been conclusively observed despite five decades of research. In the present work, soliton trains will be directly created in the presence of spin imbalance, thereby engineering the LO state.

我们的现代世界是由电子运行的，它们通过我们的智能手机，计算机和机器流动，以执行从数据存储和计算到繁重升降机的无数任务。令人惊讶的是，我们没有更好地了解电子如何一起工作。该奖项支持对一种新型物质的研究，这是一种强烈相互作用原子的超低气体，其表现在许多方面，例如电子。例如，就像金属在低温下变成“超导”，并且开始无电抗能，原子气体也会变成“超流体”，原子在没有摩擦的情况下流动。但是，由于原子间相互作用的强烈，在金属中的电子密度缩放到金属中的电子密度，原子气将出现多流量。就像电子一样，以及质子和中子，原子也属于称为费米子的粒子类，它们不能共享一个和同一状态。这项要求使计算变得非常困难，并且必须进行实验以了解费米子的行为。原子费米气体被限制在人造的“盒子”中，将是一个原始平台，可以学习在现代材料中发生的强烈相互作用费米的等式，例如高温超导体，但也在中子星中和核物质。在这些研究和其他研究的帮助下，我们可能会了解如何实现室温超导性。该项目还具有观察新的典型物质状态，例如超氧化物 - 一种超氟，也像晶体一样被订购。这项研究将为研究生提供刺激性的学习经验。原子的费米气体代表了典型的典型形式，在这些范式中，颗粒间相互作用的所有细节，外部限制和旋转组成都在众所周知，并在其控制下。实验者。该项目采用锂6原子的费米气体来试图回答有关二维系统和三维系统的热力学的长期问题，2）在旋转失衡的情况下，费米尼克超流体的命运； 3）非 - 费米子超流体中的平衡动力学。费米气体将局限于量身定制的电位，特别是均匀的盒子电位和混合谐波电位。创建同质的费米气体将消除许多现有的实验局限性，以获得准确的热力学信息。盒子电势允许访问以前没有观察到的费尔米金物质的新阶段。 Berezinskii-Kosterlitz-在两个维度上以二维为具有代数顺序的无与伦比的超级流体，将在不均匀的陷阱中掩盖。在旋转不平衡存在下，在存在旋转失衡的情况下，应通过形成一系列孤子片来自发打破翻译对称性，在该词素中，多余的费米子位于顺序参数的节点中。这描述了著名的Larkin-Ovchinnikov（LO）州，这是一个超olid物质阶段，尽管进行了五十年的研究，但仍未得到最终观察。在目前的工作中，将在旋转不平衡的情况下直接创建Soliton火车，从而使LO状态进行工程。