Quantum Electromagnetics: From SemiClassical Framework to Full Quantum Approach
讲座名称  Quantum Electromagnetics: From SemiClassical Framework to Full Quantum Approach 
讲座时间  20171021 10:00:00 
讲座地点  西安电子科技大学北校区图书馆西裙楼三楼报告厅 
讲座人  Wei E.I. Sha（沙威） 
讲座人介绍 
Wei E.I. Sha received the B.S. and Ph.D. degrees in Electronic Engineering at Anhui University, Hefei, China, in 2003 and 2008, respectively. From Jul. 2008 to Jul. 2017, he was a Postdoctoral Research Fellow and then a Research Assistant Professor in the Department of Electrical and Electronic Engineering at the University of Hong Kong, Hong Kong. Now, he is an Assistant Professor in the College of Information Science & Electronic Engineering at Zhejiang University, Hangzhou, China.
He has published 90 peerreviewed journal papers included in Web of Science. His works were widely cited by different academic societies, with the Google Scholar citations of 3340 times. He has contributed 18 invited talks in international conferences, and received four Best Student Paper Prizes and one Young Scientist Award with his students. In 2015, he was awarded Second Prize of Science and Technology from Anhui Province Government, China. In 2017, he was awarded the Marie SkłodowskaCurie Individual Fellowship of European Commission and the Thousand Talents Program for Distinguished Young Scholars of China.
Dr. Sha is an IEEE senior member and an OSA member. He engages in theoretical and computational research in electromagnetics and optics, focusing on the multiphysics and interdisciplinary areas. His research involves fundamental and applied aspects in plasmonics, emerging photovoltaics, metasurfaces, quantum electrodynamics, and computational electromagnetics.

讲座内容 
Modeling electromagnetic fieldmatter interaction plays an essential role in technology and science. Solving classical Maxwell’s equations with bulk electromagnetic parameters including permittivity and permeability is a commonlyused tool to understand physical effects and optimize engineering designs. At the quantum regime, when the size of quantum particles (atoms, molecules, quantum dots, and superconducting circuits) is pretty small compared to wavelength (typically smaller than 10 nm at optical frequencies), the “homogenized” bulk permittivity and permeability of the classical Maxwell equation is invalid or meaningless to describe electromagnetic responses of the quantum particles. In this situation, quantum effects become significant and therefore the particle system needs to be quantized.
If the field intensity is strong or the number of photons is large, semiclassical MaxwellSchrödinger system is adopted to simulate the electromagnetic fieldparticle interaction, where electromagnetic field is treated as a classical field interacting with the quantum particles. The coupled MaxwellSchrödinger system can be solved by a unified Hamiltonian approach with a symplectic framework. Versatile interesting physical phenomena involving Rabioscillation, radiative decay and shift, electromagnetically induced transparency, saturable absorption, and highharmonic generation can be reproduced by the semiclassical framework.
If the field intensity is very weak or the number of photons is quite small, both particle system and electromagnetic system must be quantized and classical Maxwell equation breaks down. Regarding quantization of Maxwell equation in lossy and dispersive media, the quantized fieldmatterbath system is still an energyconserving Hamiltonian system. When the matter couples to a heat bath (environment), it loses energy to the bath; simultaneously, the bath feeds the energy back to the matter system. This obeys the spirits of thermal equilibrium, fluctuationdissipation theorem, and detailed balance theory. As a result, we could introduce the loss to the quantized fieldmatter system by regarding the heat bath as a Langevin source or noise current. The use of ubiquitous Green’s function is still present in the full quantum calculations, which find rich applications in a great amount of cuttingedge problems, such as spontaneous emission, single photon detection, cavity quantum electrodynamics, and quantum interference.
天线与微波技术国家重点实验室 电子工程学院 天线与电磁散射研究所 超高速电路设计与电磁兼容教育部重点实验室

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