Department of Physics and CQIQC, University of Toronto, Toronto, Ontario, Canada.
JILA, NIST and Department of Physics, University of Colorado, Boulder, CO, USA.
Nature. 2023 Jan;613(7943):262-267. doi: 10.1038/s41586-022-05405-6. Epub 2023 Jan 11.
Exchange-antisymmetric pair wavefunctions in fermionic systems can give rise to unconventional superconductors and superfluids. The realization of these states in controllable quantum systems, such as ultracold gases, could enable new types of quantum simulations, topological quantum gates and exotic few-body states. However, p-wave and other antisymmetric interactions are weak in naturally occurring systems, and their enhancement via Feshbach resonances in ultracold systems has been limited by three-body loss. Here we create isolated pairs of spin-polarized fermionic atoms in a multiorbital three-dimensional optical lattice. We spectroscopically measure elastic p-wave interaction energies of strongly interacting pairs of atoms near a magnetic Feshbach resonance. The interaction strengths are widely tunable by the magnetic field and confinement strength, and yet collapse onto a universal curve when rescaled by the harmonic energy and length scales of a single lattice site. The absence of three-body processes enables the observation of elastic unitary p-wave interactions, as well as coherent oscillations between free-atom and interacting-pair states. All observations are compared both to an exact solution using a p-wave pseudopotential and to numerical solutions using an ab initio interaction potential. The understanding and control of on-site p-wave interactions provides a necessary component for the assembly of multiorbital lattice models and a starting point for investigations of how to protect such systems from three-body recombination in the presence of tunnelling, for instance using Pauli blocking and lattice engineering.
在费米子体系中，交换反对称的对波函数可以导致非常规超导体和超流体。在可控制的量子系统（如超冷气体）中实现这些状态，可以实现新的量子模拟、拓扑量子门和奇异的少体态。然而，在自然发生的体系中，p 波和其他反对称相互作用较弱，而在超冷体系中通过费什巴赫共振增强它们的效果受到三体损耗的限制。在这里，我们在多轨道三维光晶格中创建了孤立的自旋极化费米子对。我们通过光谱学测量了接近磁费什巴赫共振的强相互作用原子对的弹性 p 波相互作用能。相互作用强度可以通过磁场和约束强度广泛调节，但在重新缩放为单个晶格点的谐能量和长度标度时，会坍塌到一个通用曲线上。没有三体过程，可以观察到弹性幺正 p 波相互作用，以及自由原子和相互作用原子对之间的相干振荡。所有的观察结果都与使用 p 波赝势的精确解以及使用从头算相互作用势的数值解进行了比较。在位 p 波相互作用的理解和控制为组装多轨道晶格模型提供了必要的组成部分，并且为研究如何在存在隧道的情况下保护这些系统免受三体复合提供了起点，例如使用泡利阻塞和晶格工程。
