Understanding transport processes in complex nanoscale systems, like ionic conductivities in nanofluidic devices or heat conduction in low-dimensional solids, poses the problem of examining fluctuations of currents within nonequilibrium steady states and relating those fluctuations to nonlinear or anomalous responses. We have developed a systematic framework for computing distributions of time integrated currents in molecular models and relating cumulants of those distributions to nonlinear transport coefficients. The approach elaborated upon in this perspective follows from the theory of dynamical large deviations, benefits from substantial previous formal development, and has been illustrated in several applications. The framework provides a microscopic basis for going beyond traditional hydrodynamics in instances where local equilibrium assumptions break down, which are ubiquitous at the nanoscale.

理解复杂纳米级系统中的传输过程，如纳米流体装置中的离子电导率或低维固体中的热传导，提出了检查非平衡稳态内的电流波动并将这些波动与非线性或异常响应联系起来的问题。我们开发了一个系统框架，用于计算分子模型中时间积分电流的分布，并将这些分布的累积量与非线性传输系数相关联。从这个角度阐述的方法遵循动态大偏差理论，受益于大量先前的正式发展，并已在多个应用中得到说明。