具有Onsager-Casimir对称性的记忆：黏弹性流体中的旋转粒子
Memory with Onsager-Casimir symmetry: Rotating particle in a viscoelastic fluid
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中文总结 AI 辅助
该研究通过实验与理论结合，揭示黏弹性流体中旋转布朗粒子的随机动力学，建立满足Onsager-Casimir对称性的最小模型，解释旋转增强扩散率及产生反对称互相关的现象。
中文摘要 AI 辅助
我们研究非马尔可夫流体中旋转布朗粒子的随机动力学。实验上，我们发现旋转会增强粒子的长时扩散率，并在垂直于旋转轴的平面内正交位移分量之间产生时间反对称的互相关。为解释这些观测结果，我们引入一个最小线性模型，其中示踪粒子与慢浴自由度耦合，旋转通过平流耦合引入。消除浴变量后得到具有非互易记忆核的广义朗之万方程，该核随时间旋转形成对数螺旋，且在旋转矢量反转时满足Onsager-Casimir对称性及对应的涨落-响应关系。从后者我们得到一个几何构造，将两次时间的互相关与粒子在体相的横向响应关联起来，与普通爱因斯坦关系不同，该关系涉及响应的反对称部分。我们的实验与理论定性一致，确立了黏弹性流体中的旋转胶体作为时间非局域随机动力学中Onsager-Casimir对称性的最小实现。
英文摘要
We study the stochastic dynamics of a rotating Brownian particle in a non-Markovian fluid. Experimentally, we find that rotation enhances the long-time diffusivity of the particle and generates time-antisymmetric cross-correlations between orthogonal displacement components in the plane perpendicular to the rotation axis. To rationalize these observations, we introduce a minimal linear model in which a tracer is coupled to a slow bath degree of freedom and rotation enters through an advective coupling. Eliminating the bath variable yields a generalized Langevin equation with a non-reciprocal memory kernel. This kernel rotates in time, forming a logarithmic spiral, and it obeys Onsager-Casimir symmetry under reversal of the rotation vector, and the corresponding fluctuation-response relation. From the latter we obtain a geometric construction that links two-time cross-correlations to the transverse response of the particle in bulk. Unlike the ordinary Einstein relation, this relation involves the antisymmetric sector of the response. Our experiments and theory are in qualitative agreement, establishing rotating colloids in viscoelastic fluids as a minimal realization of Onsager-Casimir symmetry in time-nonlocal stochastic dynamics
