虚光子初探  

Tentative Study on Virtual Photons

作　　者：黄志洵[1] 石正金 

机构地区：[1]中国传媒大学信息工程学院,北京100024 [2]广州安泰化学公司,广州510665

出　　处：《中国传媒大学学报（自然科学版）》2011年第1期19-30,35,共13页Journal of Communication University of China：Science and Technology

摘　　要：不可直接观测的光子被称为虚光子。在量子电动力学(QED)中,真空态是以能量21ω和动量21→k为标志的,并指出真空能会在一个吸引力(Casimir力)作用下使两个互相平行的导体板有靠近的趋势。在一般情况下,要了解虚光子必须先全面了解光子,但后者仍有许多问题有待解决,光的波粒二象性理论也有待研究和完善。零点能(ZPE)概念是经典物理与量子物理的重要区别之一,并不能否定;但在近年来的研究中,物理学家用光子作为振荡源的随机分布,或用标量场及场的Green函数径迹,可顺利完成对Casimir力的推导。虽然多年来人们援引Ca-simir效应作为量子场的ZPE是实际存在的迹象,但令人惊奇的是不用零点起伏(甚至不用真空)也能导出Casimir的结果,亦即ZPE不在计算中出现。换言之,对Casimir效应描述而言ZPE是启发性的辅助计算手段,但并非必要条件。这就留下了深层的疑问——ZPE为何缺乏真实存在的实验证据?消失态在电磁环境中是常见的,基本特点是场强随距离增大而指数地减小,并在传播方向上无相移。可以认为消失态具有虚的波矢量。已有若干研究工作显示,由QED表述的虚光子特性在一些消失模实验中被观察到。因而从物理意义上提出了下述观点——消失模是虚光子。When the photons are not direcly observable,they are regarded as virtual.In QED,the vacuum state has an energy and a linear momentum.The QED also give that two conducting parallel plates attract each other with a force（Casimir force） due to the vacuum energy.In common case,we must try to find out about the whole situation of photons before making an understanding on virtual photons,but it is difficult because it is problematic in many respects.The theory of wave-particle duality of light must further study and seek a satisfactory solution.The concept of zero-point energy is one of the important difference between the classical physics and the quantum physics,so it cannot deng the truth.But in recent advances of research,the physicist used a random distribution of oscillating sources of photons,or used a scalar field and in terms of the trace of the Greens function for the fluctuating field,the Casimir force derivation can complete in the conceptual framework.However,many years the Casimir effect is often invoked as decisive evidence that the ZPE of quantum fields are real,but in surprising,it is possible to derive the Casimir＇s result without any reference to zero point fluctuations or even to the vacuum,i.e.the ZPE do not enter the calculation.In other words,the concept of ZPE is a heuristic and calculational aid in the description of Casimir effect,but not a necessity.Then,the deeper question remains-why there is no experiment evidence for the reality of ZPE？The evanescent states are common in the electromagnetic environments,it＇s basic feature is the field strength decrease according to the exponential law from original position to far away,and the field do not experience a phase shift in propagation direction.It seems that the evanescent state have a imaginary wave vector.In previous works,the special properties of virtual photons elaborated by QED approaches have been observed in several experiments with evanescent modes.Then,there is a thought in physical meaning——evanescent modes are virtual

关 键 词：虚光子 Feynman图 零点能 CASIMIR力 消失态 

分 类 号：O431.2[机械工程—光学工程]