James Franck Institute, University of Chicago, Chicago, IL, USA.
Enrico Fermi Institute, University of Chicago, Chicago, IL, USA.
Nature. 2022 Feb;602(7895):68-72. doi: 10.1038/s41586-021-04250-3. Epub 2022 Feb 2.
Interactions in many-body physical systems, from condensed matter to high-energy physics, lead to the emergence of exotic particles. Examples are mesons in quantum chromodynamics and composite fermions in fractional quantum Hall systems, which arise from the dynamical coupling between matter and gauge fields. The challenge of understanding the complexity of matter-gauge interaction can be aided by quantum simulations, for which ultracold atoms offer a versatile platform via the creation of artificial gauge fields. An important step towards simulating the physics of exotic emergent particles is the synthesis of artificial gauge fields whose state depends dynamically on the presence of matter. Here we demonstrate deterministic formation of domain walls in a stable Bose-Einstein condensate with a gauge field that is determined by the atomic density. The density-dependent gauge field is created by simultaneous modulations of an optical lattice potential and interatomic interactions, and results in domains of atoms condensed into two different momenta. Modelling the domain walls as elementary excitations, we find that the domain walls respond to synthetic electric field with a charge-to-mass ratio larger than and opposite to that of the bare atoms. Our work offers promising prospects to simulate the dynamics and interactions of previously undescribed excitations in quantum systems with dynamical gauge fields.
多体物理系统中的相互作用，从凝聚态物质到高能物理，都会导致奇异粒子的出现。例如，在量子色动力学中的介子和分数量子霍尔系统中的复合费米子，它们是物质和规范场之间动力学耦合的结果。理解物质-规范相互作用的复杂性的挑战可以通过量子模拟来辅助，超冷原子通过创建人工规范场，为量子模拟提供了一个通用的平台。模拟奇异的新兴粒子物理的一个重要步骤是合成人工规范场，其状态取决于物质的存在。在这里，我们演示了在具有由原子密度决定的规范场的稳定玻色-爱因斯坦凝聚体中确定性地形成畴壁。密度相关的规范场是通过同时调制光学晶格势和原子间相互作用而产生的，导致凝聚到两个不同动量的原子畴。将畴壁建模为基本激发，我们发现畴壁对合成电场的响应具有大于且与裸原子相反的电荷-质量比。我们的工作为模拟具有动力学规范场的量子系统中以前未描述的激发的动力学和相互作用提供了有希望的前景。
