报告人：Lars Bojer Madsen教授

主持人：倪宏程研究员

时 间：10月15日15:00至17:00

地 点：闵行校区光学大楼B325

Zoom会议：https://nyu.zoom.us/j/95435113581

报告人简介：

Lars Bojer Madsen教授1998年博士毕业于丹麦Aarhus大学，1998至2000年在德国马普量子光学所从事博士后研究，2000年回到丹麦Aarhus大学工作，担任副教授，2012年晋升为教授，2015年起同时兼任Aarhus大学计算中心主任以及鲁东大学兼职教授。Madsen教授以一己之力开创了丹麦的强场阿秒物理研究领域，迄今已发表科技论文250余篇，包括31篇Physical Review Letters，1篇Science，1篇Review of Modern Physics，2篇Nature Physics，1篇Nature Communications，H因子达46，组织了十余场国际学术会议，并担任Physical Review A编委。Madsen教授2011年当选日本学术振兴会会士，2012年获得世界文化理事会国际影响力特别推荐，2018年当选美国物理学会会士。

报告内容简介：

Any atom or molecule will ionize when exposed to an intense laser pulse. The ionization event is the initial key step that triggers subsequent dynamics that can lead to high-order harmonic generation (HHG), above-threshold ionization or multiple ionization. In this talk, I will discuss three topics. First, briefly, I will review theory for the ionization process from the perspective of the weak-field asymptotic tunneling theory [1]. This theory accounts for effects of a permanent dipole in the ionizing system. Second, I will discuss theory for nondipole effects in strong-field ionization based on an expansion of the vector potential to the leading order in 1/c, with c the speed of light [2]. This work is inspired by recent increase in experimental evidence in such nondipole effects. I will show how the nondipole effects modify the photoelectron momentum distributions [3]. Third, I will discuss the formulation of the strong-field approximation in the Kramers-Henneberger frame [4]. This approach supplements the three-step model for HHG by offering an alternative interpretation of the generating process, an interpretation that is relevant for laser picoscopy in atoms.

[1] Oleg I. Tolstikhin, Toru Morishita, and Lars Bojer Madsen, Theory of tunneling ionization of molecules: Weak-field asymptotics including dipole effects, Phys. Rev. A 84, 053423 (pages 17) (2011).

[2] Simon Vendelbo Bylling Jensen, Mads Middelhede Lund and Lars Bojer Madsen, Nondipole strong-field-approximation Hamiltonian, Phys. Rev. A. 101, 043408 (pages 14) (2020).

[3] Mads Middelhede Lund and Lars Bojer Madsen, Nondipole photoelectron momentum shifts in strong-field ionization with mid-infrared laser pulses of long duration, https://arxiv.org/abs/2107.00355 Accepted for publication in J. Phys. B.

[4] Lars Bojer Madsen, Strong-field approximation for high-harmonic generation in infrared laser pulses in the accelerated Kramers-Henneberger frame, https://arxiv.org/abs/2106.08824