标题： 非中心对称绝缘体中弛豫时间近似下的非线性电导问题 显示英文标题

标题： Problem of nonlinear conductivity within relaxation time approximation in noncentrosymmetric insulators

摘要： 随着激光技术的最新进展，人们对非线性和非微扰现象（如非互易输运、非线性霍尔效应和非线性光学响应）的兴趣日益增加。 在分析非平衡稳态时，量子运动方程中的松弛时间近似法（RTA）被广泛使用。 然而，最近的研究强调了使用RTA时需要仔细考虑的问题。 在发表于《Phys. Rev. B》, $\textbf{109}$, L180302 (2024) 的一项研究中，我们揭示了RTA在预测弱电场下绝缘体有限线性电导率方面存在缺陷，并基于Redfield方程改进了RTA。 在这篇文章中，我们将这种方法进一步扩展到非线性响应。 该方法为RTA提供了一个简单的替代方案，并有望用于非线性和非平衡现象的研究。 显示英文摘要

摘要： With the recent advancements in laser technology, there has been increasing interest in nonlinear and nonperturbative phenomena such as nonreciprocal transport, the nonlinear Hall effect, and nonlinear optical responses. When analyzing the nonequilibrium steady state, the relaxation time approximation (RTA) in the quantum kinetic equation has been widely used. However, recent studies have highlighted problems with the use of RTA that require careful consideration. In a study published in Phys. Rev. B, $\textbf{109}$, L180302 (2024), we revealed that the RTA has a flaw in predicting finite linear conductivity even for insulators under weak electric fields, and improved the RTA based on the Redfield equation. In this paper, we further extend our approach to nonlinear responses. This approach provides a simple alternative to RTA and is expected to be useful for the study of nonlinear and nonequilibrium phenomena.