报告摘要：

Modeling electromagnetic field-matter interaction plays an essential role in technology and science. Solving classical Maxwell’s equations with bulk electromagnetic parameters including permittivity and permeability is a commonly-used 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, semi-classical Maxwell-Schrödinger system is adopted to simulate the electromagnetic field-particle interaction, where electromagnetic field is treated as a classical field interacting with the quantum particles. The coupled Maxwell-Schrödinger system can be solved by a unified Hamiltonian approach with a symplectic framework. Versatile interesting physical phenomena involving Rabi-oscillation, radiative decay and shift, electromagnetically induced transparency, saturable absorption, and high-harmonic generation can be reproduced by the semi-classical 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 field-matter-bath system is still an energy-conserving 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, fluctuation-dissipation theorem, and detailed balance theory. As a result, we could introduce the loss to the quantized field-matter 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 cutting-edge problems, such as spontaneous emission, single photon detection, cavity quantum electrodynamics, and quantum interference.

 

沙威，男，生于1982 年4 月。2003 年7 月与2008 年6 月毕业于安徽大学，分别获电子信息工程专业工学学士和电磁场与微波专业工学博士学位。2008年7 月至2012 年5 月，在香港大学电机电子工程系从事博士后研究工作；2012年6 月至2017 年7 月任该系的研究助理教授、博士生导师。2017 年，入选第十三批国家“千人计划”青年项目，并同时获欧盟“地平线-2020”研究与创新框架下的“玛丽居里学者计划”资助。2017 年10 月至今，任职于浙江大学信息与电子工程学院，特聘研究员、博士生导师。

 

沙威研究员已合作撰写了2 本专著和4 章专书。他已发表SCI 检索论文90 篇，包括ESI高被引论文5篇，并贡献18 个国际会议邀请报告。Google Scholar 引用3400 多次，h-index 指数26。他是美国电气电子工程师学会高级会员和美国光学学会会员。他在电磁学领域国际会议EDAPS, ACES, ICCEM, PIERS, IMWS-AMP 等兼任分会主席、程序委员会委员、评奖或评审委员会委员、客座编辑等职位。他也是电磁学研究进展期刊（PIER）的编委。沙威研究员是40多个国际期刊的特邀审稿人，2014年被评为Journal of Computational Physics 期刊“杰出审稿人”。2013年获香港大学研究成果奖，2015年获安徽省科学技术奖二等奖。他合作指导的博士生在国际会议上获四次最佳学生论文奖，一次青年科学家奖。他当前的研究领域包括电磁学、纳米光子学、非线性及量子光学、光电子学、及多物理场分析。