光子真是简单的无质量粒子吗？——光子概念再剖析  

Is photon simply a massless particle?——The concept of photon revisited

作　　者：汪克林[1] 曹则贤[2] WANG Ke-Lin;CAO Ze-Xian(Department of Modern Physics,University of Science and Technology of China,Hefei 230026,China;Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]中国科学技术大学近代物理系,合肥230026 [2]中国科学院物理研究所,北京100190

出　　处：《物理》2019年第11期726-732,共7页Physics

摘　　要：在近代物理文献中,光子常常作为无质量粒子被提及。然而,光子同有质量粒子行为上有本质上的不同,从有质量粒子的物理学简单地令m=0不可能得到任何光子物理。光(子)的能量-动量色散关系,速度之参照框架的(非)依赖(性),自旋与自旋投影等基本物理性质都完全不同于有质量粒子。光子与有质量粒子的玻色-爱因斯坦统计上的差别也不是粒子质量有无的问题。光子概念来自基于实验结果提出的光场之能量量子,光场量子化同有质量粒子能量的量子化采用了完全不同的方案。光场量子化是对不同光场模式直接引入产生和湮灭算符,不同模式的光场之间没有作用,谈论光子的位置没有意义,则光子的计数性--其与定域性有关--也就成了问题。严格考察关于光(子)性质的描述及其背后的物理图像,可作为进一步深入理解光(子)之本性的开始。Photon is often referred to as a massless particle, but this is in no sense an adequate designation. The physics for photon can never be recovered from that for massive particles by simply setting m=0. The energy-momentum relation, the(in-)dependence of velocity on the reference frame, spin and the projection of spin, to name just a few, are some aspects that show radical differences between photon and massive particles. Even in terms of Bose-Einstein statistics which both may observe, the difference does not lie in the fact whether the objects of concern are with or without mass. Photon is de facto referred to the energy quantum of the radiation field, which was proposed in the effort to fit experimental results. Quantization for the light field has followed a different scheme as for massive particles, it is simply realized by replacing the amplitude of the radiation field with annihilation and creation operators. Since it is impossible to define a position operator, thus the countability, being relevant to the locality problem, of the photon turns out to be rather questionable. The current article tries to provide a comprehensive review over the concept of photon in the framework of quantum mechanics, relativity and statistical physics, in the hope of provoking a re-examination of the precise formulations and underlying pictures concerning this fundamental notion.

关 键 词：光子 无质量粒子 量子化 位置算符 定域性 可计数性 

分 类 号：G63[文化科学—教育学]