电磁波极化的应用

极化是电磁波的一个重要参量,是电动力学、电磁场与电磁波课程教学中的重点内容之一.系统介绍电磁波极化这一概念在通信、雷达和抗干扰等方面的应用,即利用电磁波极化实现无线电信号的最佳发射和接收,利用极化提高通信容量,探讨了电磁波极化在雷达目标识别、检测、成像以及抗干扰中的应用.     

从电动力学到量子电动力学：纳米光电子器件

纳米尺度下的光电器件的研制与米、毫米、微米尺度下电子器件或光学器件的研制在基本原理与制造技术上有本质的不同。必须采用量子电动力学和介观物理作为基本原理。在量子电动力学中,光子与电子可以相互转化,光子也可以储存在“空腔”中。光一电转换或光一电一光的转换甚至可以在远小于一个光波的尺度内实现（如100nm以下）。基于大量最新现象发现的启示与推动,产生了一种全新的光予技术：纳米光子技术。在这种全新的纳光子技术中,人们将光子电子的输运与转化联合起来进行考虑,非线性光学获得了长足的发展。微电子技术和概念被大量地推广应用于纳光子技术开发。创新型元件如集成激光器、30dB光放大器、效率为30％的1．55μm滤波器等层出不穷地涌现。纳米技术的研发为信息储存、输运和处理开辟了新的天地。进入21世纪,纳米光子技术研究日新月异。在摩尔经验规律的指导下,不断发展的微电子工业的制造精度已进入100nm领域。大规模应用纳米电子、纳米光子技术的时代已经来临。一些新型的光通讯线路已开始应用纳米光子器件。对公众而言,用于照明的LED只是一个应用实例。报告将结合法国国家纳米研究平台的研发成果来阐述纳米光子学的原理和纳米光子器件发展的趋势。     

Generalized variational principles for boundary value problem of electromagnetic field in electrodynamics

An expression of the generalized principle of virtual work for the boundary value problem of the linear and anisotropic electromagnetic field is given. Using Chien＇s method, a pair of generalized variational principles （GVPs） are established, which directly leads to all four Maxwell＇s equations, two intensity-potential equations, two constitutive equations, and eight boundary conditions. A family of constrained variational principles is derived sequentially. As additional verifications, two degenerated forms are obtained, equivalent to two known variational principles. Two modified GVPs are given to provide the hybrid finite element models for the present problem.     

关于前沿研究融入电动力学课程教学的探索

电动力学是一门研究电磁场规律的重要课程,其抽象的理论和繁杂的数学推导让学生很难理解和掌握,同时传统的教学内容和教学手段很难调动学生的学习兴趣.通过将前沿研究与经典教学内容有机结合,并以MATLAB,COMSOL等科研软件作为辅助教学工具,将抽象的物理概念可视化,实现教学内容和教学手段与时俱进.此举不仅可以激发学生学习兴...     

The de Haas—van Alphen Oscillation in Two—Dimensional QED at Finite Temperature and Density

The de Haas-van Alphen oscillations in two-dimensional QED at finite temperature and density are investigated.It is shown that for a given particel density,besides the oscillation of magnetization,the chemical potential is also oscillating with the same period.Different from the earloier work (J.O.Andersen and T.Haugset,Phys.Rev.D51 (1995) 3073),the magnetization oscillations we studied have a correct nonrelativistic limit at zero temperature.     

微机构可调谐阵列滤光片的设计与模型分析

提出一种新颖的采用薄膜技术在玻璃基底上构造微机可调谐二维窄带滤光片阵列的方法,对器件进行了膜系设计及光谱响应模拟,通过器件的电动力学模型分析,设计出器件的形状与尺寸。     

Teleportation of a two-atom entangled state using a single EPR pair in cavity QED

We propose a scheme for teleporting a two-atom entangled state in cavity quantum electrodynamics (QED). In the scheme, we choose a single Einstein--Podolsky--Rosen (EPR) pair as the quantum channel which is shared by the sender and the receiver. By using the atom--cavity-field interaction and introducing an additional atom, we can teleport the two-atom entangled state successfully with a probability of 1.0. Moreover, we show that the scheme is insensitive to cavity decay and thermal field.     

Protocol for multi-party superdense coding by using multi-atom in cavity QED

We present a protocol for multi-party superdense coding by using multi-atom in cavity quantum electrodynamics (QED). It is shown that, with a highly detuned cavity mode and a strong driving field, the protocol is insensitive to both cavity decay and thermal field. It is even certain to identify GHZ states via detecting the atomic states. Therefore we can realize the quantum dense coding in a simple way in the multiparty system.     

Quantum Nonlocality and Generation of Multi-mode Schrodinger Cat States

We describe the Greenberger-Horne-Zeilinger (GHZ) paradox in the multi-mode Schroedinger cat states.We also show that the multi-mode cat states violate the Bell‘s inequality by an amount that grows exponentially with number of modes. The test of quantum nonlocality is based on parity measurement and displacement operation, which are experimentally feasible. We also describe a scheme for the generation of the cat states in cavity QED.     

Real-Time Thermal Ward-Takahashi Identity for Vectorial Current in QED and QCD

It is shown that by means of canonical operator approach the Ward-Takahashi identity (WTI) at finite temperature T and finite chemical potential μ for complete vectorial vertex and complete fermion propagator can be simply proven, rigorously for Quantum Electrodynamics, and approximately for Quantum Chromodynamics, where the ghost effect in the fermion sector is neglected. The WTI shown in the real-time thermal matrix form will give definite thermal constraints on the imaginary part of inverse complete Feynman propagator including self-energy for fermion and will play an important role in relevant physical processes. When the above inverse propagator is assumed to be real, the thermal WTI will essentially be reduced to its form at T=μ=0 thus one can use it in the latter‘s form. At this point, a practical example is indicated.