Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
Fakultät für Physik, Ludwig-Maximilians-Universität, 80799 München, Germany.
Science. 2016 Sep 16;353(6305):1257-60. doi: 10.1126/science.aag1635.
The repulsive Hubbard Hamiltonian is one of the foundational models describing strongly correlated electrons and is believed to capture essential aspects of high-temperature superconductivity. Ultracold fermions in optical lattices allow for the simulation of the Hubbard Hamiltonian with control over kinetic energy, interactions, and doping. A great challenge is to reach the required low entropy and to observe antiferromagnetic spin correlations beyond nearest neighbors, for which quantum gas microscopes are ideal. Here, we report on the direct, single-site resolved detection of antiferromagnetic correlations extending up to three sites in spin-1/2 Hubbard chains, which requires entropies per particle well below s* = ln(2). The simultaneous detection of spin and density opens the route toward the study of the interplay between magnetic ordering and doping in various dimensions.
排斥哈伯德哈密顿量是描述强关联电子的基础模型之一，被认为可以捕捉高温超导的基本特征。光学晶格中的超冷费米子允许对哈伯德哈密顿量进行模拟，从而可以控制动能、相互作用和掺杂。一个巨大的挑战是达到所需的低熵，并观察到超出最近邻的反铁磁自旋关联，而量子气体显微镜是理想的工具。在这里，我们报告了在自旋为 1/2 的哈伯德链中直接、单站点分辨地探测到的反铁磁关联，其扩展到三个位置，这需要每个粒子的熵远低于 s* = ln(2)。自旋和密度的同时探测为研究各种维度中的磁有序和掺杂之间的相互作用开辟了道路。
