讲座主题：Piecewise ensemble averaging stochastic Liouville equations for simulating non-Markovian quantum dynamics

专家姓名：严运安

工作单位：鲁东大学

讲座时间：2022年8月29日10:00-11:00

讲座地点：物电学院1511报告厅

主办单位：烟台大学物理与电子信息学院

内容摘要：

The stochastic scheme is a fruitful tool for simulating the challenging non-Markovian quantum dynamics. Its performance at long time, however, degrades due to the intrinsic fast increase in the variance of the quantum Brownian motion. This talk presents the recent progress on developing the stochastic Liouville equations with piecewise stationary noises. Starting from a conventional stochastic scheme, we can always decompose the involved noises into two parts: the principal part assuming piecewise correlations and the auxiliary part recovering the full correlation. A partial stochastic average over the auxiliary noises yields a stochastic Liouville equation that only involves noises with piecewise correlations and can hence be averaged separatedly for different time intervals. Meanwhile the dissipative influence of the auxiliary noises is rigorously incorporated with integrals over the functional derivatives with respect to the principal noises. The working equation now assumes a similar structure to the non-Markovian quantum state diffusion. Thanks to the noise disentanglement in different time intervals, we can perform piecewise ensemble average and serve the average of the preceding interval as the initial condition of the subsequent propagation. This strategy avoids the long-time stochastic average and the corresponding statistical errors will be saturated at long times. This talk will give numerical results for the spontaneous decay of two-state atoms and the spin-boson model and shows that the suggested method enables us to simulate the long-time quantum dissipative dynamics with long memories in the non-perturbative regime.

主讲人介绍：

严运安，鲁东大学教授。2002年于中国科学院理论物理研究所获博士学位，2002-2012年，先后在中国科学院化学研究所、美国德克萨斯理工大学、德国柏林自由大学、德国罗斯托克大学和日本九州大学进行博士后和访问学者研究，2012年加入贵州师范学院，2018年加入鲁东大学。严运安教授目前的研究方向是发展新方法模拟凝聚相中分子体系的耗散动力学。