Topic (题目): Quantum regimes of Free Electron Lasers and Laser-driven Particle Accelerators: Does the ‘size’ of free electron wavefunction have physical effect?
Speaker (报告人):Dr. Yiming Pan (潘义明)
(Department of Physics of Complex Systems, Weizmann Institute of Science, Israel)
Date (时间):2019年5月22日（周三）上午9:30
Place (地点):北京大学技物大院激光加速实验楼二楼会议室
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Abstract: In light-matter interaction, does the electron spatial size affect its radiative interaction or energy transfer (acceleration/deceleration)? The interpretation and the essence of the electron quantum wavepacket and its electromagnetic interactions have been a subject of debate since the early conception of quantum mechanics. Nowadays, modern QED theory and experiments indicate that spontaneous emission by a free electron is independent of its wavepacket dimensions. Contrary to spontaneous emission, stimulated radiative interaction may depend on the wavepacket characteristics. Here, we analyze the energy transfer (and stimulated interaction) of a single electron quantum wavepacket with coherent radiation when the electron passes through a grating in an example of Smith-Purcell radiation scheme analytically and numerically. We show that net synchronous acceleration of a single electron is fundamentally impossible beyond a critical pre-drift length of the electron due to the wavepacket size expansion beyond the radiation wavelength. Below this range, such wavepacket-dependent acceleration is possible, approaching the limit of classical 'point-particle' acceleration. In the quantum wave limit our analysis emulates the FEL (free electron laser) gain formula in the quantum plane-wave limit, and exhibits the quantum energy/momentum sidebands characteristics of PINEM (photon-induced near-field electron microscopy). Finally, we propose to use the transition between the quantum and point-particle regimes as a way for experimental measurement of the electron wavepacket size, which is a fundamental question in modern physics. The analysis of electron wavepacket-dependence behavior is applicable to a wider class of free electron radiation and acceleration schemes, like FEL, Cerenkov and Transition Radiation and Dielectric Laser Acceleration (DLA).
Biography:
Dr. Yiming Pan (潘义明) (Ph.D.-physics), is a Post-Doc researcher of Department of Physics of Complex Systems, Weizmann Institute of Science (2018-present), and Department of Electrical Engineering Physical Electronics, Tel Aviv University (2016-2018), Israel. Dr. Pan got his BSc in applied physics at Anhui University (2010), and PhD degree in theoretical physics on quantum transport at Nanjing University (2016), China. During PhD, he worked on the quantum transport of Weyl semimetals and two-dimensional materials, and photonic simulation on optical analogies of topological insulators. Currently, Dr. Pan researches mainly focus on Laser-driven Particle Accelerator and Free Electron Laser, and Quantum Weak Measurement in light-matter interactions and ultracold fields, Floquet topological photonics and quantum transport, in collaboration with Avraham Gover (Tel Aviv University), Eliahu Cohen (Bar Ilan University), Ido Kaminer (Technion), Qingqing Cheng (USST), Yaron Silberberg (WIS) and Nir Davidson (WIS). For recently, he has published and accepted several works in the journals such as PRL (2), Nat. Commu. (1), Laser & Photon. Rev (1) and Adv. Mat. (3). Please find more details of his interests and projects online: https://www.researchgate.net/profile/Yiming_Pan2.
Contact person （联系人）：刘克新（kxliu@pku.edu.cn）黄森林（huangsl@pku.edu.cn)
