近日，德国马克斯·普朗克量子光学研究所的Timon A. Hilker&Dominik Bourgund及其研究团队取得一项新进展。经过不懈努力，他们揭示混合维冷原子费米-哈伯德系统中单个条纹的形成。相关研究成果已于2025年1月1日在国际权威学术期刊《自然》上发表。

据研究人员所知，本文首次在采用混合维度（mixD）设置的冷原子费米-哈伯德量子模拟器中观察到了单个条纹的特征。通过将空穴-空穴吸引的能量尺度提高到自旋交换能量的水平，研究人员进入了条纹开始形成的有趣交叉温度区间。研究人员观察到空穴掺杂剂之间存在扩展的吸引相关性，并发现形成类似单个条纹的更大结构的概率增加。

在自旋部分，研究人员研究了高达三阶的相关函数，结果支持条纹的形成。这些观察结果被视为条纹相的前兆，条纹相的特征是交错的电荷和自旋密度波有序，其中波动的掺杂剂线将反铁磁序相反的区域分隔开。

据悉，d波超导与条纹相之间的关系对于理解高温铜氧化物超导体中的有序相至关重要。这些有序相可能受到各向异性耦合的强烈影响，从而提高临界温度，这一点在最近镍酸盐中超导性的发现中得到凸显。利用超冷原子的量子模拟器提供了一个多功能平台，可以设计这种耦合，并以单粒子分辨率在实空间中观察涌现的结构。

附：英文原文

Title: Formation of individual stripes in a mixed-dimensional cold-atom Fermi–Hubbard system

Author: Bourgund, Dominik, Chalopin, Thomas, Bojovi, Petar, Schlmer, Henning, Wang, Si, Franz, Titus, Hirthe, Sarah, Bohrdt, Annabelle, Grusdt, Fabian, Bloch, Immanuel, Hilker, Timon A.

Issue&Volume: 2025-01-01

Abstract: The relation between d-wave superconductivity and stripes is fundamental to the understanding of ordered phases in high-temperature cuprate superconductors. These phases can be strongly influenced by anisotropic couplings, leading to higher critical temperatures, as emphasized by the recent discovery of superconductivity in nickelates. Quantum simulators with ultracold atoms provide a versatile platform to engineer such couplings and to observe emergent structures in real space with single-particle resolution. Here we show, to our knowledge, the first signatures of individual stripes in a cold-atom Fermi–Hubbard quantum simulator using mixed-dimensional (mixD) settings. Increasing the energy scale of hole–hole attraction to the spin exchange energy, we access the interesting crossover temperature regime in which stripes begin to form. We observe extended, attractive correlations between hole dopants and find an increased probability of forming larger structures akin to individual stripes. In the spin sector, we study correlation functions up to the third order and find results consistent with stripe formation. These observations are interpreted as a precursor to the stripe phase, which is characterized by interleaved charge and spin density wave ordering with fluctuating lines of dopants separating domains of opposite antiferromagnetic order.

DOI: 10.1038/s41586-024-08270-7

Source: https://www.nature.com/articles/s41586-024-08270-7