近日，德国多特蒙德工业大学的Zhe Wang及其研究团队取得一项新进展。经过不懈努力，他们实现观察到斥性束缚磁振子。相关研究成果已于2024年6月26日在国际权威学术期刊《自然》上发表。

本文给出了类伊辛链反铁磁体BaCo₂V₂O₈中排斥束缚三磁振子态和束缚磁振子对的光谱特征。在大型横向场中，在量子临界点以下，研究人员通过比较太赫兹光谱测量结果与海森堡-伊辛链反铁磁体(一种典型的量子多体模型)的理论结果，来确定排斥束缚的磁振子态。

实验结果显示，这些高能、排斥束缚的磁振子态与连续体清晰分离，表现出了显著的动力学响应。尽管存在耗散，但其寿命足够长，能够被明确识别。鉴于磁振子束缚态能够改变自旋链中的输运性质，研究人员设想这些状态可以成为磁振子量子信息处理技术的重要资源。

据悉，由引力形成的强子、原子核、原子、分子、超导对等稳定的复合对象在自然界中无处不在。相比之下，通过排斥力稳定的复合对象长期以来被认为是理论结构，因为它们在自然发生的系统中很脆弱。令人惊讶的是，由强排斥相互作用形成的束缚原子对已经在光学晶格中得到了实验证明。尽管如此，由于存在强烈的衰变通道，人们普遍认为在凝聚态物质中不存在类似的排斥束缚粒子对。

附：英文原文

Title: Experimental observation of repulsively bound magnons

Author: Wang, Zhe, Halati, Catalin-Mihai, Bernier, Jean-Sbastien, Ponomaryov, Alexey, Gorbunov, Denis I., Niesen, Sandra, Breunig, Oliver, Klopf, J. Michael, Zvyagin, Sergei, Lorenz, Thomas, Loidl, Alois, Kollath, Corinna

Issue&Volume: 2024-06-26

Abstract: Stable composite objects, such as hadrons, nuclei, atoms, molecules and superconducting pairs, formed by attractive forces are ubiquitous in nature. By contrast, composite objects stabilized by means of repulsive forces were long thought to be theoretical constructions owing to their fragility in naturally occurring systems. Surprisingly, the formation of bound atom pairs by strong repulsive interactions has been demonstrated experimentally in optical lattices. Despite this success, repulsively bound particle pairs were believed to have no analogue in condensed matter owing to strong decay channels. Here we present spectroscopic signatures of repulsively bound three-magnon states and bound magnon pairs in the Ising-like chain antiferromagnet BaCo₂V₂O₈. In large transverse fields, below the quantum critical point, we identify repulsively bound magnon states by comparing terahertz spectroscopy measurements to theoretical results for the Heisenberg–Ising chain antiferromagnet, a paradigmatic quantum many-body model. Our experimental results show that these high-energy, repulsively bound magnon states are well separated from continua, exhibit notable dynamical responses and, despite dissipation, are sufficiently long-lived to be identified. As the transport properties in spin chains can be altered by magnon bound states, we envision that such states could serve as resources for magnonics-based quantum information processing technologies.

DOI: 10.1038/s41586-024-07599-3

Source: https://www.nature.com/articles/s41586-024-07599-3