颤动(德语：Zitterbewegung；英语：jitter/oscillatory movement)是一种理论上螺旋的或圆形的基本粒子运动，尤其是电子，因而产生了它们所具有的自旋与磁矩。如此运动的存在是由埃尔温·薛丁格于1930年首次提出，这是出于他对自由空间中相对论性电子的狄拉克方程序波包解的分析结果，其中正与负的能态间的干涉产生了看起来是以光速绕着中央的位置变动，其角频率为或用频率表示为大约1.6×10赫兹。

自由的相对论性粒子的颤动迄今未被观察到。

Krekora等人的研究成果，基于二次量子化量子理论（适合描述多粒子量子动力学的理论）显示出：「量子场论禁止一颗电子颤动现象的出现。」Krekora等人亦将他们量子场论的数值仿真用在描述另一个具有争议性（且某种程度相关）的现象，称作克莱因悖论。

Zitterbewegung ("trembling motion" from German) is a hypothetical rapid motion of elementary particles, in particular electrons, that obey the Dirac equation. The existence of such motion was first proposed by Erwin Schrödinger in 1930 as a result of his analysis of the wave packet solutions of the Dirac equation for relativistic electrons in free space, in which an interference between positive and negative energy states produces what appears to be a fluctuation (at the speed of light) of the position of an electron around the median, with an angular frequency of , or approximately 1.6×10 radians per second. A re-examination of Dirac theory, however, shows that interference between positive and negative energy states may not be a necessary criterion for observing zitterbewegung.