题目：Attosecond correlated electron-lattice dynamics in solids

报告人：孟胜

邀请人：王孝群

时间：2025年6月13日（周五）下午15:30

地点：紫金港校区海纳苑8幢215报告厅

摘要：

Photoexcitation and the resultant attosecond quasiparticle dynamics is a powerful means in distinguishing different interactions and manipulating the states of matter, especially in complex quantum materials. Here we investigate photoexcitation-induced correlated electron-lattice dynamics at the attosecond timescale with the recently developed new theoretical tools incorporating both nonadiabatic electron-nuclear couplings and nuclear quantum effects. In particular, we uncover the attosecond ultrafast processes of exciton formation, evolution and dissociation in monolayer hexagonal boron nitride, and the subsequent exciton-exciton interference phenomenon, where the resulting oscillatory signals of electron occupation allow us to extract phase information of exciton envelope function. Another example is the attosecond process of high harmonics generation (HHG) in solids. The lack of consideration for couplings between HHG and other quasiparticles, such as phonons, impedes our understanding of many-body interactions in HHG. Coherent phonons are revealed to effectively affect HHG via the adiabatic band modulation induced by phonon deformation effects and the nonadiabatic nonequilibrium distribution of photocarriers in multiple valleys. The adiabatic and nonadiabatic mechanisms leave their fingerprint via influencing the phonon period and phase delay in the oscillation of HHG intensity, both of which are experimentally measurable. Investigation of these quantities enables the direct probing of the exciton-exciton and electron-phonon interactions in materials. 

个人简介：

孟胜，中科院物理所研究员、国科大岗位教授、表面物理国家重点实验室主任，2024年美国物理学会会士，国家杰出青年科学基金获得者，国家重点研发计划项目首席科学家。2000 年中国科技大学毕业，2004 年获中科院物理所凝聚态物理博士学位，同年获瑞典Chalmers 理工大学应用物理博士学位。2005-2009年在哈佛大学物理系任博士后。2009年7月回国任特聘研究员。主要从事凝聚态体系的非平衡态超快量子动力学研究。发表论文 400 余篇，包括 Phys. Rev. Lett.二十余篇，Nature 及 Science 子刊十余篇，总引用 20,000 余次，H-index为72。