Can repelling electrons form bound pairs

Abstract

Electrons are elementary particles that repel each other due to their same electric charge. In certain cases however, the effect of quantum coherence in an appropriate environment may act to overcome this natural tendency making the electrons effectively behave as if there was an attraction between them, and form bound pairs that move as a unit. We discuss a simple case, where this unexpected binding is mediated by a rigid crystalline environment. The paper is addressed to students and teachers with an elementary knowledge of quantum and solid state physics.