德国马克斯普朗克量子光学研究所Sarah Hirthe小组提出了超冷原子费米子阶梯中的磁介导空穴配对。这一研究成果发表在2023年1月18日出版的国际学术期刊《自然》上。

在这里，课题组通过实验观察到这个长期存在的理论预测，报告了由于超冷原子量子气体中的磁关联而导致的空穴配对。通过设计具有混合维度耦合的掺杂反铁磁梯，研究人员在短尺度上抑制了空穴的泡利阻塞。这导致了结合能的显著增加和成对尺寸的减小，并观察到主要占据梯子的同一梯级空穴对。

该课题组人员发现了一个超交换能量级的空穴-空穴结合能，并且随着掺杂的增加，他们观察到对分布的空间结构，表明束缚空穴对之间存在排斥作用。通过设计一种结合力强烈增强的结构，该课题组描述了一种提高超导临界温度的策略。

研究人员表示，传统的超导是由声子介导的电荷载流子(电子或空穴)配对产生的。在许多非常规超导体中，配对机制被推测是由磁关联介导的，正如掺杂反铁磁体中的移动电荷模型所捕捉到的那样。然而，对真实材料中潜在机制的精确理解仍然缺乏，并且在过去40年里一直推动着实验和理论研究。早期的理论研究预测了在阶梯体系中磁介导的掺杂配对，其中理想化的理论玩具模型解释了如何在排斥相互作用下产生配对。

附：英文原文

Title: Magnetically mediated hole pairing in fermionic ladders of ultracold atoms

Author: Hirthe, Sarah, Chalopin, Thomas, Bourgund, Dominik, Bojovi, Petar, Bohrdt, Annabelle, Demler, Eugene, Grusdt, Fabian, Bloch, Immanuel, Hilker, Timon A.

Issue&Volume: 2023-01-18

Abstract: Conventional superconductivity emerges from pairing of charge carriers—electrons or holes—mediated by phonons1. In many unconventional superconductors, the pairing mechanism is conjectured to be mediated by magnetic correlations2, as captured by models of mobile charges in doped antiferromagnets3. However, a precise understanding of the underlying mechanism in real materials is still lacking and has been driving experimental and theoretical research for the past 40 years. Early theoretical studies predicted magnetic-mediated pairing of dopants in ladder systems4,5,6,7,8, in which idealized theoretical toy models explained how pairing can emerge despite repulsive interactions9. Here we experimentally observe this long-standing theoretical prediction, reporting hole pairing due to magnetic correlations in a quantum gas of ultracold atoms. By engineering doped antiferromagnetic ladders with mixed-dimensional couplings10, we suppress Pauli blocking of holes at short length scales. This results in a marked increase in binding energy and decrease in pair size, enabling us to observe pairs of holes predominantly occupying the same rung of the ladder. We find a hole–hole binding energy of the order of the superexchange energy and, upon increased doping, we observe spatial structures in the pair distribution, indicating repulsion between bound hole pairs. By engineering a configuration in which binding is strongly enhanced, we delineate a strategy to increase the critical temperature for superconductivity.

DOI: 10.1038/s41586-022-05437-y

Source: https://www.nature.com/articles/s41586-022-05437-y