发表机构
Vica Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade; University of Criminal Investigation and Police Studies（维察核科学研究所-塞尔维亚共和国国家研究所，贝尔格莱德大学; 刑事调查与警察研究大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究基于Mori-Zwanzig框架，构建TTG响应正向模型，将TTG瞬态解释为有效传输算子的响应，建立了从TTG测量到微观传输动力学粗粒化描述的系统路径。
AI 中文摘要
瞬态热光栅（TTG）测量可探测亚微米空间尺度和亚纳秒时间尺度上的热传输，已在多种固态系统中观测到其偏离纯扩散行为的现象。在Mori-Zwanzig投影框架内，这类效应可被解释为观测尺度下未解析的微观自由度所产生的记忆的体现。受此观点启发，我们构建了TTG响应的正向模型，其中热传输由带记忆的线性演化算子描述。微观传输过程被系统粗粒化为非马尔可夫传输算子，其有限记忆形式为TTG动力学提供了通用描述，而扩散行为和长记忆行为则作为同一基础框架的渐近极限出现。在该框架内，实验观测到的TTG瞬态被解释为有效传输算子的响应，而非特定微观传输机制的直接特征。反演过程的主要结果是确定有效算子参数，而微观传输机制仅通过后续的材料特定建模步骤推断。因此，所提出的受Mori-Zwanzig启发的框架建立了从TTG测量到有效传输算子、再到微观传输动力学粗粒化描述的系统路径。
英文摘要
Transient thermal grating (TTG) experiments provide a powerful means of probing material properties and resolving their dynamics at small spatio-temporal scales through the temporal response to a spatially periodic excitation. However, quantitative interpretation of the measured transient requires a forward model that consistently connects energy deposition, subsequent transport, and detection within the finite space-time window of the experiment, for which such a formulation is still lacking in TTG. Here, we formulate a continuum, operator-based TTG forward model in which the physical processes from energy deposition to detection of the evolving spatial mode are treated within a unified transfer-function framework. Thermal transport dynamics is represented by a temporal memory kernel, allowing unresolved relaxation processes to be incorporated at the scale of experimental observability without imposing an a priori microscopic transport mechanism. The formulation provides a basis for inferring effective material properties and the dynamics resolved within the experimental window, which can subsequently be related to material-specific microscopic degrees of freedom and their interactions. In addition, analysis of the resulting TTG transients shows that the observability of flux memory is not equivalent to the presence of oscillations in the measured response. Oscillations provide a clear signature when finite flux-relaxation dynamics becomes resolved on the experimental time scale, whereas their absence does not imply the Fourier limit. Memory can instead remain observable through non-oscillatory modifications of the transient shape and characteristic time scales.
Comments27 pages, 6 figures
