发表机构
Institute of Theoretical Physics, Faculty of Physics, University of Warsaw; Department of Physics, University of Michigan（华沙大学物理学院理论物理研究所; 密歇根大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出实频极点与矩展开方法，直接计算多体微扰论谱量，通过受控再压缩防止极点增殖，并在量子杂质与均匀电子气中验证系统收敛。
AI 中文摘要
有限温度多体理论通常在虚时中表述，便于进行高效数值处理。然而，从虚轴提取谱性质是困难的，需要数值解析延拓，而在实轴上的直接表述则需要代价高昂的数值求积。在本文中，我们使用系统可改进的极点和矩展开来表示多体微扰理论的对象，并开发了直接在实轴上评估图解贡献的相应框架。我们引入了一种受控的再压缩程序，以防止在代数和图解操作下极点的增殖。我们在典型的量子杂质问题上对该方法进行了基准测试，并将其应用于均匀电子气的自洽计算。所得谱量系统地收敛至数值精度。这项工作为在图解多体理论（包括自洽守恒方法）中对谱量进行受控且系统可改进的计算提供了一个实用框架。
英文摘要
Finite-temperature many-body theories are typically formulated in imaginary time, where they are amenable to efficient numerical treatment. However, the extraction of spectral properties from the imaginary axis is difficult and requires numerical analytic continuation, while a direct formulation on the real axis requires prohibitively expensive numerical quadrature. In this paper, we represent the objects of many-body perturbation theory using systematically improvable pole and moment expansions and develop the corresponding framework for evaluating diagrammatic contributions directly on the real axis. We introduce a controlled recompression procedure that prevents the proliferation of poles under algebraic and diagrammatic operations. We benchmark the approach on paradigmatic quantum impurity problems and apply it to self-consistent calculations of the uniform electron gas. The resulting spectral quantities converge systematically towards numerical accuracy. This work provides a practical framework for controlled and systematically improvable calculations of spectral quantities within diagrammatic many-body theories, including self-consistent conserving approaches.
Comments20 pages, 15 figures
