Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
J Chem Theory Comput. 2022 Apr 12;18(4):2047-2061. doi: 10.1021/acs.jctc.1c00477. Epub 2022 Mar 1.
The emergence of experiments capable of probing quantum dynamics at the single-molecule level requires the development of new theoretical tools capable of simulating and analyzing these dynamics beyond an ensemble-averaged description. In this article, we present an efficient method for sampling and simulating the dynamics of the individual quantum systems that make up an ensemble and apply it to study the nonequilibrium dynamics of the ubiquitous spin-boson model. We generate an ensemble of single-system trajectories, and we analyze this trajectory ensemble using tools from classical statistical mechanics. Our results demonstrate that the dynamics of quantum coherence is highly heterogeneous at the single-system level due to variations in the initial bath configuration, which significantly affects the transient exchange of coherence between the system and its bath. We observe that single systems tend to retain coherence over time scales longer than that of the ensemble. We also compute a novel thermodynamic entanglement entropy that quantifies a thermodynamic driving force favoring system-bath entanglement.
能够在单分子水平上探测量子动力学的实验的出现需要开发新的理论工具，这些工具能够模拟和分析这些动力学，超越对平均描述的依赖。在本文中，我们提出了一种有效的方法来对组成集合的各个量子系统的动力学进行采样和模拟，并将其应用于研究无处不在的自旋-玻色子模型的非平衡动力学。我们生成了单个系统轨迹的集合，并使用经典统计力学的工具来分析这个轨迹集合。我们的结果表明，由于初始浴配置的变化，量子相干动力学在单系统水平上具有高度的异质性，这会显著影响系统与浴之间相干的瞬态交换。我们观察到，单个系统往往会在比集合更长的时间尺度上保持相干。我们还计算了一种新的热力学纠缠熵，它量化了有利于系统-浴纠缠的热力学驱动力。
