Electron electric dipole moment

The electron electric dipole moment (EDM) is a measure of the distribution of electric charge within the electron. In quantum mechanics, a dipole moment is a vector quantity that illustrates the separation of positive and negative charges. In the case of the electron, which is typically considered to be a fundamental particle with no substructure, the EDM would represent a permanent separation of charge, implying a nonzero dipole moment along some axis.