发表机构
College of Physics, Jilin University; Department of Computer Science, University of York（吉林大学物理学院; 约克大学计算机系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究指出费米子输运噪声中拓扑贡献消失是特例，多带玻色子输运噪声中拓扑内容可通过频率分辨的电流互谱区分，相关协议适用于Cu(1,3-bdc)且鲁棒性良好。
AI 中文摘要
对于费米面上的电子，贝里曲率的拓扑部分会从输运噪声中消失：反常霍尔电导率是量子化的，且霍尔电流的涨落与陈数无关。我们表明，这种抵消是费米面的一个特例，对于玻色子而言并不成立。磁振子和声子会热占据每一个能带，每个能带都有其自身的陈数，因此曲率的霍奇分解的调和部分并非单一常数，涨落不会将其湮灭。保留下来的是被占据能带中陈数的占据权重色散。能带几何在电流噪声中是可见的，在零温度下，噪声求和规则的反对称部分已经能返回一个陈数；新的是一种在零温度下没有对应物的物理量，仅在多个能带被占据且权重不同时存在。我们从涨落玻尔兹曼方程推导得出，在涨落层面解决了能量-磁化强度的相减问题：相减项是有界磁化强度密度的旋度，因此它对任何单次实现的输运测量记录的电流贡献恰好为零。该物理量是否可测量？驱动协议不可行：过剩噪声比平衡噪声基底低12个数量级。平衡协议可行，通过电流互谱反对称部分的求和规则实现，该求和规则无驱动，因此无抑制效应。我们证明，该求和规则的频率积分形式无法区分拓扑和几何内容，而频率分辨的互谱在可及分辨率下可区分二者。该协议针对Cu(1,3-bdc)指定，其对无关模型完备性、色散、测温及磁场校准具有鲁棒性。
英文摘要
We show that the equilibrium transport noise of a multiband bosonic system carries a measurable imprint of its Chern numbers, and we give the protocol that extracts them. For electrons the topological part of the Berry curvature is absent from the transport noise: over a filled band it yields the quantized anomalous Hall conductivity, yet at a Fermi surface the Chern number is invisible to the fluctuations of the Hall current. That cancellation is an accident of the Fermi surface: magnons and phonons populate every band thermally, each with its own Chern number, so the harmonic sector of the Hodge decomposition is not a single constant, and a variance does not annihilate it. What survives is the occupation-weighted dispersion of Chern numbers. That current noise sees band geometry is known, and at zero temperature the antisymmetric part of the noise sum rule already returns a Chern number; the new element is an object with no zero-temperature analogue, existing only when several bands are populated and weighted differently. We derive it from a fluctuating Boltzmann equation and resolve the energy-magnetization subtraction at the level of fluctuations: the subtracted term is a curl, contributing exactly zero to the current a transport measurement records, and no magnetization auto-correlation enters the antisymmetric cross-spectrum at any wavevector. Measurement uses an equilibrium sum rule on that cross-spectrum, with no drive and hence no suppression: its frequency-integrated form cannot in practice separate topological from geometric content, for a rank reason, whereas the frequency-resolved form does, at accessible resolution. The protocol is specified for Cu(1,3-bdc), with calibration and robustness characterized. A driven alternative lies twelve orders below the equilibrium floor. Two independent implementations agree on every convention-free quantity.
Comments20 pages, 5 figures, 6 tables; code and data at doi:10.5281/zenodo.21945238; companion paper: arXiv:2608.15789
