标题： 探索超冷费米子在离子哈伯德模型中的竞争密度序 显示英文标题

标题： Exploring competing density order in the ionic Hubbard model with ultracold fermions

摘要： 我们通过将相互作用的两组分费米原子气体加载到光晶格中，实现了并研究了离子 Hubbard 模型。 双部分晶格具有蜂窝状几何结构，并具有交错的能量偏移，这明确地破坏了反转对称性。 通过测量原子动量分布的噪声关联，识别出不同的密度有序相。 对于弱相互作用，几何结构诱导出电荷密度波。 对于强排斥相互作用，我们检测到双占据位点的强烈抑制，这符合莫特绝缘态的预期，并且外部破坏的反转对称性在密度分布中不再可见。 在不同配置下的局部密度分布通过测量双占据晶格位点的数量随相互作用和能量偏移的变化来表征。 我们进一步利用方向依赖调制光谱探测系统的激发，并发现了一个复杂的光谱，我们将它与一个理论模型进行比较。 显示英文摘要

摘要： We realize and study the ionic Hubbard model using an interacting two-component gas of fermionic atoms loaded into an optical lattice. The bipartite lattice has honeycomb geometry with a staggered energy-offset that explicitly breaks the inversion symmetry. Distinct density-ordered phases are identified using noise correlation measurements of the atomic momentum distribution. For weak interactions the geometry induces a charge density wave. For strong repulsive interactions we detect a strong suppression of doubly occupied sites, as expected for a Mott insulating state, and the externally broken inversion symmetry is not visible anymore in the density distribution. The local density distributions in different configurations are characterized by measuring the number of doubly occupied lattice sites as a function of interaction and energy-offset. We further probe the excitations of the system using direction dependent modulation spectroscopy and discover a complex spectrum, which we compare with a theoretical model.