We introduce a new regularization of the Redfield equation based on a replacement of the Kossakowski matrix with its closest positive semidefinite neighbor. Unlike most of the existing approaches, this procedure is capable of retaining the time dependence of the Kossakowski matrix, leading to a completely positive divisible quantum process. Using the dynamics of an exactly-solvable three-level open system as a reference, we show that our approach performs better during the transient evolution, if compared to other approaches like the partial secular master equation or the universal Lindblad equation. To make the comparison between different regularization schemes independent from the initial states, we introduce a new quantitative approach based on the Choi-Jamiolkowski isomorphism.
A comparison of different master equations for driven-dissipative dynamics in composite quantum systems: Dispersive readout in structured electromagnetic environments
Sorbonne Université（索邦大学）；Institut des NanoSciences de Paris（巴黎纳米科学研究所）；LPENS, Département de Physique, École Normale Supérieure, Centre Automatique et Systèmes (CAS), MINES ParisTech, Université PSL, Sorbonne Université, CNRS, Inria（物理与能源环境研究实验室，巴黎高等师范学院，自动系统与中央研究院，国立巴黎高等矿业学校，巴黎文理研究大学，索邦大学，法国国家科学研究中心，法国国家信息与自动化研究所）；CNRS（法国国家科学研究中心）
Exact solution of Markovian master equations for quadratic fermi systems: thermal baths, open XY spin chains, and non-equilibrium phase transition
本文将三次量子化方法推广到用4 n × 4 n矩阵对角化的方法统一精确地处理n个费米子二次系统的Redfield和Lindblad主方程。从Redfield方程出发，详细分析了非平衡热驱动。我们解释如何计算所有物理相关的量，如非平衡期望值的本地观测，各种熵或信息措施，或时间演化和性质的放松。我们还讨论了如何确切地处理显式时间相关的问题。然后，一般的形式主义，研究热驱动的开放XY自旋1/2链。我们发现，最近提出的非平衡量子相变在开放的XY链生存的Redfield模型内的热驱动。特别是，长程磁相关的相位可以通过非平衡稳态对外部（浴或体）参数的超敏性来表征。研究的热传输，我们发现足够强的热驱动的负热导，以及非单调依赖的热流浴耦合的强度。
