It has been a long-sought goal of quantum simulation to find answers to outstanding questions in condensed-matter physics. A famous example is finding the ground state and the excitations of the two-dimensional (2D) Hubbard model with strong repulsion below half-filling. This system is a doped antiferromagnet and is of great interest because of its possible relation to high-Tc superconductors. Theoretically, the fermion excitations of this model are believed to split up into holons and spinons, and a moving holon is believed to leave behind it a string of “wrong” spins that mismatch with the antiferromagnetic background. Here, we show that the properties of the ground-state wavefunction and the holon excitation of the 2D Hubbard model can be revealed in unprecedented detail by using the imaging and the interference technique in atomic physics. They allow one to reveal the Marshall sign of the doped antiferromagnet. The region of wrong Marshall sign indicates the location of the holon string.

在凝聚态物理中寻找悬而未决的问题的答案一直是量子模拟的长期目标。一个著名的例子是找到半填充以下具有强排斥力的二维（2D）Hubbard模型的基态和激发。该系统是掺杂的反铁磁体，由于它与ŤC超导体。从理论上讲，该模型的费米子激发被认为是分裂成铁隆子和自旋子，并且运动的哈龙被认为会留下一系列与反铁磁背景不匹配的“错误”自旋。在这里，我们表明，通过使用原子物理学中的成像和干涉技术，可以以前所未有的细节揭示2D Hubbard模型的基态波函数和holon激发的特性。它们允许人们揭示掺杂的反铁磁体的马歇尔信号。错误的马歇尔符号区域表示冬瓜串的位置。