Spectral densities of disordered quantum magnets

无序量子磁体的光谱密度

• 批准号: 392499956
• 负责人: Professor Dr. Kai Phillip Schmidt
• 金额: --
• 依托单位: PSI LAB für Neutronenstreuung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/392499956?language=en
• 关键词: Spectral; densities; disordered; quantum; magnets

Disorder is inevitable in condensed matter physics and is known to be the source of interesting novel physics, e.g. it can change quantum criticality or even destroy quantum phase transitions. At the same time it is typically hard to treat disorder theoretically which is especially true for dynamical correlation functions. The latter are desired quantities, since high-resolution spectroscopy on materials with intentional doping are becoming a focus experimentally. In this project we apply white-graph expansions in the framework of perturbative continuous unitary transformations to treat gapped phases of disordered quantum magnets. Disorder averages are taken either for large finite systems or directly in the thermodynamic limit, so an effective quasi-particle picture is derived which goes well beyond mean-field approaches for gapped quantum phases.

无序在凝聚态物理中是不可避免的，被认为是有趣的新物理的来源，例如，它可以改变量子临界性，甚至破坏量子相变。同时，通常很难从理论上处理无序，特别是对于动态关联函数。后者是理想的量，因为故意掺杂材料的高分辨率光谱正成为实验上的焦点。在这个项目中，我们在微扰连续么正变换的框架下应用白图展开来处理无序量子磁体的带隙相。对于大型有限系统或直接在热力学极限中取无序平均，从而得到了一种有效的准粒子图像，它远远超出了带隙量子相的平均场方法。