Electrical Point Contacts: A Classic Tool Enters the Quantum Age

摘要

The study of electron transport through point contacts in metals has a long history going back to Maxwell's 19th century investigations of the resistance of an orifice in the diffusive transport regime [1]. Point contact spectroscopy, now a classic tool for studying the electron-phonon interaction in metals, was developed much later. The quantum transport regime was reached in the late 1980's when the conductance of semiconductor quantum point contacts was found to be quantized in units of e~2/h (e is the elementary charge unit and h is Planck's constant). Very recently single-atom point contacts in metals have been fabricated. The chemical valence of the single contact atom has been found to determine the macroscopic conductance of the entire circuit in which the contact is embedded. In this review a selective history of some of the many exciting developments in the study of point contacts will be presented.